Base catalysed rearrangements involving ylide intermediates. Part 17. The preparation and thermal rearrangement of pentadienylammonioamidates

摘要

I. CHEM. SOC. PERKIN TRANS. I 1983 1041 Base Catalysed Rearrangements involving YIide Intermediates. Part 17.1 The Preparation and Thermal Rearrangement of Pentadienylammonio-amidates Kan Chantrapromma, W. David Ollis,’ Ratnasamy Somanathan, and Ian 0. Sutherland Department of Chemistry, The University, Sheffield S3 7HF The thermal rearrangements of the (2’E)-penta-2’,4’-dienylammonioamidates (13) give products (1 4) and (15) that are formally derived from 1,2 and 5,2rearrangements and, in some cases, the product (1 6) of a 3,2rearrangement. The products (1 4) and (15) are formed by a radical mechanism in which (a) radical recombination to give the products (14) and (15) competes with recombination to give the ammonioamidates (13) and (19) and (b) the translational equilibration of the radical pairs (7) and (8)is fast compared with radical pair recombination and diffusion to give free radicals. The thermal rearrangements of allylammonioamidates (1 ; X = Me, OEt, NHMe, NHPh) were discussed in a previous paper in this series.’ The ylides (1) rearrange by two major pathways: a 1,2 rearrangement (1) --+ (2) probably involving a radical pair mechanism, and a 3,2rearrangement (1) --t (3) which probably proceeds by a concerted peri- cyclic mechanism.The study of the rearrangements of the ammonioamidates (1) was made more complicated by the observation that the radical pair (4), involved as an inter- mediate in the process (1) -w (2), undergoes recombination to give the starting ylide (1) in addition to the product (2) (Scheme 1).The proposed intermediacy of the radical pair (4) in the process (1) -(2) was based upon ‘ mixing ’ experiments of the same type as those used in our earlier investigation of the Stevens 1,2rearrangement of ammo- nium ylides such as (5). These experiments established that diffusion from the radical pair (4) to give free radicals com- peted with recombination to give the products (1) or (2). It was of interest therefore to use a probe for a radical pair intermediate that would detect a radical pair having an even shorter lifetime r than that required for competitive diffusion to give free radicals (r cu. 10-lo-lO-lls). A migrating penta- 2’,4’-dienyl substituent would provide such a probe t since it could be expected that for a penta-2’,4’-dienylammonio-amidate (6), yielding the radical pair (7), random recombin- ation involving positions 1’ and 5’ of the pentadienyl com- ponent would require less time than that required for diffusion to give free radicals.Thus the limited translational motion indicated by (7) L,(8) in Scheme 2 would suffice for 1’,5’-scrambling and a process involving a very short-lived radical pair (lifetime T lop8s), loss of stereochemical configuration 2.3 (T ca. 1O-lo-lO-ll s), and intramolecular cyclisation of a hexenyl radi~al.~ Mc,N -YCOX Me2NNCOX Me26-COX R’ I +-I IMc2NNCOX MeZN-CR’ COX R’* R2+Ph R2 H (31 (5 1 Scheme 1.Rearrangement reactions of allylammonioamidates. The possible involvement of the radical pair (4) in the formation of some of the product (3) is indicated by the broken arrow Me2N-kcox-COX Me2 NNCOXMe2I -1L5# (9 Me,N NCOX (11 (8) (10 1 Scheme 2. Radical pair reactions of pentadienylammonioamidates (6). The identities of the terminal carbon atoms of the pentadienyl component are indicated by the labels 1’ and 5’ The penta-2’,4‘-dienylhydraziniurn salts (1 2) were syn-thesised by the reaction of the appropriate hydrazine deriv- ative with the pentadienyl bromide. The salts (12) reacted with base to give the ammonioamidates (13) as gums or crystalline solids, charactwised by their spectroscopic pro- perties and molecular formulae (elemental analysis or high- 1042 + +Me2N N H COX Br-Me2y-kOX Me2N-NCOXI (15) (16) (19) Q; in ('z)-(16)' R'=R2= R3=H, X = Me and (19) b; R'=D,RZ=R3=H,X=Me c; R'=R3=H, R2=X =Me d; R1=R2=H,R3=X=Me e; R' = R2= R3= H, X = OEt f; R'=D, R2=R3= H, X = OEt g; R'=R3=H,R2=Me,X=OEt h; R1=R2=H,R3=Me,X =OEt i; R'=R2= R3= H, X = NHMe j; R'=D,R2=R3 = H, X =NHMe k; R1=R3=H, R2=Me,X=NHMe I; R'=R2=H,R3=Me, X=NHMe m; R'=R3 =HI R2= Me, X = NHPh n; R'=R2=H,R3=Me, X =NHPh o;R'=R2=R3=H,X =Ph p; R1=D,R2=R3:H,X=CgDg wx D D CsDsC0N H N Me2 (20) J.CHEM. SOC. PERKIN TRANS. I 1983 resolution mass spectrum). The ammonioamidates (1 3) re- arranged on heating in dry benzene to give the products (14) and (15), corresponding formally to the products of 1,2 and 5,2 rearrangements, and in some cases the product (16) of a 3,2 rearrangement.The deuteriated salts (12b), (12f), (12j), and (12p) were prepared using 1,l -'H2penta-2,4-dienyl bromide (17) obtained from the reaction of the l,l-'H2- dienol (18) with phosphorus tribromide. The compositions of the reaction products from the re- arrangement of the ammonioamidates (13) are summarised in Table 1. Two general conclusions can be drawn from these results.6 (a) The ratio of 1,2 and 5,2 products depends upon the structure of the pentadienyl group in a manner that is consistent with the derivation of these products from a radical pair analogous to (7) in which the translational motion required for the equilibration analogous to (7) =+ (8) is fast compared with radical coupling.(b) The extent of the compet- ing 3,2 rearrangement depends upon the structure of the starting yIide and is not consistent with the derivation of this product from a radical pair analogous to (7). We conclude that the product (16) is, at least in part, derived from a concerted pericyclic process 'that competes with the homoly- tic pathway for rearrangement. These conclusions are similar to those drawn from our earlier examination of the re- arrangements of allylammonioamidates and it was, therefore, of interest to determine the extent to which radical pair recombination to give the ammonioamidates analogous to (6) and (11) compared with the formation of the rearrange- ment products (14), (15), and (16).This possibility was examined using either the l', 1'-2H2pentadienylammonio-amidates(13f) and (1 3p) or the 2'-methylpentadienylammonio-amidates (13c), (13g), (13k), and (13m). The products of partial rearrangement were studied by n.m.r. spectroscopy to determine the extent to which the ammonioamidate had undergone 1',5'-pentadienyl ' scrambling ' (13) L,(19) and rearrangement (13) -(14) + (15) + (1 6) at measured times. The product compositions could be used to obtain approximate rate constants for the processes summarised in Scheme 3 (Experimental section). The results of this examin- ation (Table 3; Experimental section), although of limited quantitative significance due to the difficulty of obtaining sufficiently accurate product compositions by n.m.r.measure-Table 1. Thermal rearrangement of penta-2',4'-dienylammonioamidates(13) in benzene at 80 "C d R2 Ammonioamidate (1 3) Product ratio r- '7 f-- A X R' RZ R3 Time (h) I721 1521 C6D5 D H H 48 1 1 b Me H Me H 36 1 2 b Me H H Me 36 2 1 b Me D H H 36 1 1 b EtO H Me H 6 1 2 0.5 EtO H H Me 6 2 1 0.8 EtO D H H 8 1 1 0.3 MeNH H Me H 3 1 2 0.8 MeNH H H Me 3 2 1 1.5 MeNH D H H 6 1 1 0.6 PhNH H Me H 6 1 2 0.7 PhNH H H Me 6 2 1 1.o (i Based upon isolated products (14), (15), and (16) or n.m.r.integration in cases where products could not be separated. * This product was not formed in sufficient quantity for isolation. J. CHEM. SOC. PERKIN TRANS. I 1983 Table 2. lntramolecularity in the 1,2 and 5,2rearrangement of the 'H and *H7-penta-2',4'-dienylammonioamidates(130) + (13p) Reaction conditions Solvent GlycerolGlycerolEthylene glycol Ethylene glycol Butanol Benzene Methyl cyanide Based upon the position of the deuterium label in the pentadienyl side chain of the rearrangement product (14p) + (15p) of the 2H,amm~nioamidate (13p) as indicated by integration of the NCH2-and C=CH2signals in the n.m.r. spectrum of the reaction product. For the rearrangement of a 1 : 1 mixture of the 'H (130) and 'H7- (13p) ammonioamidates with (100 -42) intramolecularity the reaction product contains 2 of the 'HJ and z of the 'HJ products. Intra-Product ratio molecularityTemp.("C) Viscosity (cP) Time (h) El ,211WI (I 100 14.8 120 1.2 92 160 3.28 8 1.o 55 80 3.02 168 1.o 69 100 1.99 72 1.o 60 100 0.54 48 1.o 30 80 0.33 48 1.o 17 80 0.22 60 1.o 9 ments, show that in all cases the rate of 1',5'-pentadienyl scrambling in the ammonioamidate is comparable with the overall rate of rearrangement, but in only one case (13m) is it actually faster than the rate of rearrangement. Thus although the product ratios recorded in Table 1 may be modified by 1',5'-pentadienyl scrambling (1 3) +(19) the two general conclusions, (a) and (b), drawn from these results do not require modification.It was also of interest to determine the extent to which the rearrangement reactions of the pentadienylammonioamidates were intramolecular in solvents of varying viscosity and whether, in very viscous solvents, the translational motion required for the radical pair equilibration (7) I,(8) would become slow compared with the radical pair recombination to give the products (9) and (10). The ammonioamidate (130) was chosen for this study since the heptadeuterio-derivative (13p) could be synthesised readily using l,l-2H2penta-2,4-dienyl bromide ( 17) and 1-2H,benzoyl-2,2-dimethylhydr-azine (20). The determination of the intramolecularity of the rearrangement was carried out as in our earlier investigation ofthe mechanism of the Stevens I ,2 rearrangement of ammo- nium ylides and the results are summarised in Table 2.As ex- pected, the intramolecularity of the rearrangement is only high in solvents of high viscosity, but even under conditions where the rearrangement shows considerable intramolecularity (>50) the ratio of the products of 1,2 and 5,2 coupling indicates that the translational equilibration (7) =F(8) is complete in all but one case -/' before radical pair recombina- tion takes place. This probe for the detection of short-lived radical intermediates is therefore likely to prove more sensitive than the more conventional probes based upon the retention of configuration of the migrating group and intramolecularity. This conclusion will be exploited in future papers in this series.Experimental For general directions see Part 1.9 (2E)-1, l-2H2Penta-2,4-dienol (1 8).-A solution of ethyl (2E)-penta-2,4-dienoate lo (7.0 g) in anhydrous ether (50 ml) j-The n.m.r. spectrum of the product from the rearrangement in glycerol at 100 "C shows a slight preponderance of 1,2 coupling, but in view of the ,errors inherent in the integration of n.m.r. signals (510 estimated error) the estimated ratio of 1.2 (Table 2) can hardly be regarded as being significantly different from the ratio of 1.0 found for all other cases. was added slowly to a suspension of lithium aluminium deuteride (2.30 g) in anhydrous ether (50 ml) at -20 "C, and the mixture was stirred at room temperature for 3 h.Excess of reducing agent was destroyed by the addition of wet ether, the mixture acidified by dropwise addition of aqueous sulphuric acid (2073, and the ether layer separated by decant- ing. The aqueous layer was washed with ether and the com- bined ether extracts were dried and evaporated. The residual oil was distilled to give the deuteriated dienol (18) as a colourless liquid (3.80 g, 77), b.p. 72-75 "C at 11 mmHg; 6 6.54-6.13 (m, CH-CH), 5.81br (d, J 15 Hz, CD2-CH=) 5.05-5.30 (m, CXH,), and 2.22 (s, OH), with no detectable signal for the OCH2 group (6 4.15) indicating >99 atom D at C-I. (2E)-1, l-2H2Penta-2,4-dienyl Bromide (1 7).-This was prepared from the above dienol by reaction with phosphorus tribromide in dry pyridine at 0 "C.The product (78 yield) was used without distillation. Preparation of Hydrazinium Salts (1 2).-An equimolar mixture of 1-acetyl-2,2-dimethylhydrazine,l-ethoxycarbonyl-2,2-dimethyl hydrazine, 1,l -dimethyl-4-p henylsemicarbazide, or 1,l ,4-trimethylsemicarbazide,and the appropriate dienyl bromide in methyl cyanide, was stirred at room temperature for 12 h. The reaction mixture was concentrated by evapor- ation and the salt precipitated by the addition of dry ether and recrystallised from ethanol-ether. Most hydrazinium salts were obtained as solids but the salts from 1,1,Ctrime- thylsemicarbazide were gums which were converted into the corresponding ylides without further purification.The follow- ing salts were prepared by this method. 2-Acetyl-l , 1-dimethyZ-l-(2'E)-penta-2',4'-dienylhydrazi-nium bromide (12a). This was obtained as crystals, m.p. 108- 109 "C (82) (Found: C, 43.5; H, 6.8; Br, 32.2; N, 11.5. C9HI7BrN20 requires C, 43.4; H, 6.8; Br, 32.1; N, 11.3); vmax.(Nujol) 3 120, 1 703, and 1 600 cm-'; G(CD30D) 6.80-6.30 (m, "CH-CH'), 5.84 (dt, J 15 and 7 Hz, CHH-CH2), + 5.55-5.27 (m, CH2), 5.33 (d, J 7 Hz, NCH2), 3.62 (s, Me2), and 2.05 (s, COCH3). 2-Acetyl-l , 1-dimethyl-1 -{(2'E)-l', 1 '-2H2penta-2',4'- dienyf)hydruzinium bromide (12b). This was obtained as crystals, m.p. 108-109 "C (80) (Found: C, 43.25; H,* 7.0; Br, 32.1; N, 11.3. C9HlSD2BrN20 requires C, 43.0; H,* 6.8; Br, 31.9; N, 11.15); 6(CD30D) 6.77-6.35 (m, * For this and other deuteriated compounds the value refers to the combined D and H content estimated as H.1044 ‘CH-CH‘), 5.85 (d, J 15 Hz,CH“CH-CD,), 5.565.30 (m, CH2), 3.63 (s, Me2), and 2.06 (s, COCH3), with no + detectable signal for the NCH2 group corresponding to >95 atom D at C-1‘. 2-Acetyl-l ,1 -dimethyl-1 -(2’-methylpent~-2’,4‘-dienyZ)-hydrazinium bromide (12c). This was obtained as crystals (88) (Found: C, 42.1 ;H, 6.9; Br, 28.6; N, 10.2. CloHIYBrNO requires C, 42.7; H, 7.5; Br, 28.5; N, 10.0); vmax.1700 cm-’; G(CD3OD) ABXY system, 6A 6.69, 6B 6.40, 6x 5.46, 6y 5.39 (JAB 10, JAX 16, JAY 10 Hz, CHB-CHAXHxHy), 4.74 (s, IkH,), 3.67 (s, Mez), 2.07 (s, COCH3), and 1.99 (s, C=CMe).2-Acetyl-1,1 -dimethyl- 1 -(4’-methylpent~-2’,4’-dienyl)-hydrazinium bromide (12d). This was obtained as crystals (82); v,,,~~.1 700 cm-’; 6(CD30D) AMX2 system, 6, 6.70, 6, 5.71, 6, 4.91 JAM 15, JMX7 HZ, CHA,=CHM-C(HX)~, 5.20br(s, C=CHz),3.85 (s, 6Me2),2.21 (s, COCH3), and 1.93 (s, CMe).2-Ethoxycarbonyl- 1,l -dimethyl- 1 -(2’E)-pent~-2’,4’-dienyl-hydrazinium bromide (1 2e). This was obtained as crystals, m.p. 89-90 “C (82) (Found: C, 43.1; H, 7.05; Br, 28.7; N, 10.3. CIOHIOBrNzOzrequires C, 43.0; H, 6.8; Br, 28.7; N, 10.1); vmax,(Nujol) 3 480-3 380, 1 742, 1 650, and 1 608 cm-’; 6(CD30D) 6.76-6.30 (m, H-CH=), 5.82 (dt, J 15, 7.5 Hz, CH=CH-CHz), 5.56-5.28 (m, CH2), 4.62 (d, J + 7.5 Hz, NCHZ), AzX3 system, 6A 4.24, 6x 1.27 JAX7 Hz, 4-OC(HA)z C(HX)J, and 2.60 (s, NMe,).2-Ethoxycarbonyl-l,l-dimethyZ-l-{(2’E)-l’,l’-2H2pentu-2’,4’-dienyl)hydraziniumbromide (1 2f).This was obtained as colourless crystals, m.p. 88-90 “C (80) (Found: C, 42.85; H, 7.0; Br, 28.6; N, 9.6. C10H17D2BrN202requires C, 42.7; H, 6.8; Br, 28.5; N, 9.6); 6(CD30D) 6.77-6.31 (m, =CH-CH=), 5.82 (d, J 15 Hz, CHH-CD2), 5.60-5.25 (m, C=CH2), AzX3 system, 6A 4.25, 6x 1.28 JAX 7 Hz, OC- I (HA)zC(Hx)3,and 2.60 (s, NMez), with no detectable signal I for CHzN corresponding to >95 atom D at C-1’. 2-Ethoxycarbonyl- 1,1 -dimethyl- 1 -I(2’E)-2‘-methyZpentu- 2’,4’-dienylhydraziniumbromide (1 2g). This was obtained as crystals, map. 101-103 “C (75) (Found: C, 45.0; H, 7.3; Br, 27.1; N, 9.3.CllHZ1BrN202requires C, 45.1; H, 7.2; Br, 27.2; N, 9.55); v,,,. 1745 cm-’; 6 6.66-6.36 (m,+ =CH-CH), 5.60-5.25 (m, C=CH2), 4.94 (s, NCH2), A2X3 system, 6A 4.24, 6, 1.28 JAX 7 Hz, OC(H,)2C(Hx)3, 3.87 (s, 6Mez), and 2.00 (s, -Me). 2-Ethoxycarbonyl- 1,l -dimethyl-1 -(2’E)-4‘-methylpenta- 2’,4’-dienylhydraziniumbromide (12h). This was obtained as a gum, contaminated with the hydrobromide salt, which was converted into the ylide without further purification; 6(CD3-OD) AMXZ system, 6, 6.72, 6M 5.76, 6x 4.72 JAM 15, JMX 7.5 Hz, CHAH~--C(Hx)z, 5.21br (s, CHz), A2X3 system, 6~ 4.28, 6, 1-30 JAX7 HZ, OC(HA)ZC(HX)~, 3.27 (s, Me2), and 1.93 (s, CMe).1,l-Dimethyl-2-methylcarbamoyl-1 -(2’E)-penta-2‘,4’- dienylhydrazinium bromide (129.This was obtained as a gum which was converted into the corresponding ylide without further purification; 6(CD30D) 6.78-6.30 (m, H-CH“), 5.86 (dt, J 7, 14 Hz, CHH-CH2), 5.51-5.27 (m, CH2), 4.64 (d, J 7 Hz, CH,), 3.60 (s, Me2), and 2.72 (s, CON-HMe). 1,l-Dimethyl-2-methylcarbamoyl-1 -{(2’E)- 1 ’,1’-2H2penta-2‘,4‘-dietiyl}hydraziniumbromide (12j). This was obtained as a gum which was converted into the corresponding ylide without further purification; 6(CD30D) 6.78-6.30 (m, H-CH=), J. CHEM. SOC. PEKKIN TRANS. I 1983 5.83 (d, J 14 Hz, CHH-CDz), 5.52-5.28 (m, C=CHz),+ 3.58 (s, NMe,), and 2.73 (s, CONHMe), with no detectable +signal for CH2N corresponding to >95 atom D at C-1’.1,l -DimethyZ-2-methylcarbamoyl-1-(2’E)-2’-methylpenta-2’,4‘-dienyllhydraziniumbromide (12k). This was obtained as a gum (70) which was converted into the corresponding ylide without further purification ;6(CD30D), ABXY system, 8A 6.70, 6, 6.50, 6x 5.40, 6y 5.36 (JAB 10, JAx 16, JAY 10 Hz, =CHA-CHB=CHxHy), 4.64 (s, CHz), 3.59 (s, Mez) 2.74 (s, CONHMe), and 1.99 (s, C’CMe). 1,l-Dimethyl-2-methylcarbamoyl-1-(2’E)-4’-methylpenta-2’,4’-dienylhydruziniumbromide (121). This was obtained as a gum (72) which was converted into the corresponding ylide without further purification; 6(CD30D), AMXz system, 6A 6.70, 6M 5.79, 6x 4.67 JAM 15, JMX 7 Hz, CHAXHM- C(HX)J, 5.19 (s, C=CHz),3.60 (s, Mez),2.72 (s, CONHMe),and 1.92 (s, CMe).1,l- Dimethyl- 1 -(2’E)-2’-methylpent~-2’,4’-dienyl-2-phenylcarbamoyZhydruziniu~ bromide (1 2m). This was ob- tained as crystals, m.p. 116-118 “C (85) (Found: C, 52.8; H, 6.8; Br, 23.3; N, 12.2. Cl5HZ2BrN30requires C, 52.9; H, 6.5; Br, 23.5; N, 12.35); vmaX.3 260, 3 200, 3 140, 1720, and 1605 cm-’; 6(CD30D) 7.50-7.06 (m, 5 aryl H), ABXY system, 6A 6.62, 6B 6.40, 6x 5.41, 6y 5.37 (JAB 10,+ JAX 16, JAY 10 Hz, =CHB-CHA=CHXHy), 4.69 (s, NCHZ), 3.67 (s, Me2), and 2.05 (s, CMe). 1,l -Dimethyl- 1 -(2’E)-4’-methylpenta-2’,4’-die~yl1-2-phenylcarbamoylhydrazinium bromide (I 2n). This was obtained as a hygroscopic solid (87); 6(CD3)zCO7.02-7.56 (m, 5 aryl H), ABX2 system, 6, 6.77, 6B 6.01, 6x 4.84 JAB 15, JBX 8 Hz, CHA=CH,-C(H~, 5.1 5 (S, C=CH),5.10 (s, C=CH), 3.79 (s, Mez), and 1.96 (s, C=CMe).2-Benzoyl- 1,l -dimethyl- 1 -(2‘E)-penta-2’,4’-dienylhydr-uzinium bromide (120).This was obtained as crystals, m.p. 112-114 “C(87) (Found: C, 54.2; H, 6.1; Br, 25.7; N, 9.2. Cl4Hl9BrN20requires C, 54.0; H, 6.1; Br, 25.7; N, 9.0);vInax.(Nujol) 1 690 and 1 605 cm-’; 6 7.99 (dd, J 8, 1.5 Hz, 2 ortho-H of C6H5), 7.63-7.33 (m, 3 aryl H), ABMXYZz system, tiA 6.64, 6, 6.33, 6M 5.76, 6, 5.36, 6y 5.29, 6, 5.05 + JAB 10, JAM 14, JBx 16, JBy 10, JMz 7 Hz, NC(Hz)z-CHM= + CHA-CHB‘CHxHy, and 3.87 (s, NMez). 2-2H,Benzoyl- 1,l -dimethyl- 1 -{(2’E)- 1 ’,1’-zHzpenta-2’,4’-dieny1)hydrazinium bromide (12p). This was obtained as crystals, m.p.112-114 “C (85) (Found: C, 52.7; H, 6.1; Br, 25.3; N, 8.8. ClrHlzD,BrNzOrequires C, 52.8; H, 6.0; Br, 25.2; N, 8.8); 6 ABMXY system, 6, 6.64, 6.33, 6, 5.76, 6x 5.36, 6y 5.29 (JAB 10, JAM 14, JBx 16, JBy 10 Hz,+ + NCDz-CHM=CHA-CHB=CHxHy), and 3.87 (s, NMe,), with + no detectable signals for C6H5and NCHz corresponding to >99 atom D in the phenyl group and >98 atom D atc-1’. Preparation of Ammonioamidates (1 3).*-The hydrazinium salt (12) was treated with an excess of aqueous sodium hydroxide (6~;2 ml for each g of salt) with stirring at room temperature for 3 h. The ylide was extracted into dichloro- methane and the extract dried and evaporated to give the ammonioamidate (13), as an oil in most cases. The crystalline ylides were purified by recrystallisation from hexane-di-* These compounds are systematically named as ammonio-amidides and -ureides.J. CHEM. SOC. PERKIN TRANS. I 1983 chloromethane; the non-crystalline ylides were used without further purification. N-{Dimethyl(2’E)-penta-2’,4’-dienylammonio}acetamidide(13a).This was obtained as an oil (83) (Found: M+, 168.1259.C9H16N20requires M, 168.1263);vmx. 1 580 cm-’; 6 6.50-6.16 (m, CHH), 5.78(dt, J 7,14Hz, CH2-CHH),+ 5.42-5.19 (m, C=CH2), 4.35 (d, J 7 Hz, NCH2), 3.25 (s, hMe2), and 1.82(s, COCH,). N-{Dimethyl(2’E)-1’,1’-2H2penta-2’,4’-dienylammonio}-acetamidide (13b). This was obtained as an oil (88) (Found: M+, 170.1390.GH14D2N20requires M, 170.1388); v,,,. 1 580 cm-’;6 6.50-6.16 (m, CH=CH), 5.77 (d, J 14 Hz,+ CD,-CH), 5.40-5.19 (m, CH,), 3.25 (s, NMe,), and 1.83 + (s, COCH3);a low intensity doublet for NCH2 indicated ca.97 atom D at C-1’. N-{Dimethyl(2‘E)-2‘-methylpenta-2‘,4’-dienylammonio}-acetamidide(13c). This was obtained as a gum (78) (Found: M+, 182.1419.CloH18N20requires M, 182.1419);vmx. 1 575 cm-’; 6 ABXY system, 6A 6.14,6, 6.58,6x 5.27,6y 5.17 (JAB 10, JBX 16,JBy 10 Hz, =CHA-CHBHxHy), 3.78 (s, Mez), 2.07(s, COCH3),and 1.99(s, CMe). N-(Dimethyl(2’E)-4‘-methylpenta-2‘,4‘-dienyfarnmonio>-acetamidide (13d). This was obtained as a gum (84)(Found: M+, 182.1426.CloH18N20requires M, 182.1419);vmX, 1 575 cm-’; 6 AMX2 system, 6A 6.46,SM 5.72,6x 4.37 JAM 15, JMx 7.5 Hz, CHA’CHM-C(Hx)2,5.10br (s, C=CH2),3.24 (s, Me2), 1.88 (s, CMe), and 1.82(s, COCH,).N-{Dimethyl(2’E)-penta-2’,4’-dienylammonio}ethoxy-formamidide (13e). This was obtained as an oil (81)(Found: M+, 198.1372. ClOHl8NZO2requires M, 198.1368); vmx. 1635 cm-’; 6 6.48-6.17 (m, H-CH=), 5.83 (dt, J 15, 7Hz,CH2-CHTH), 5.38-5.20 (m, CHz), 4.26(d, J 7 Hz,+ NCHJ, A2X3 system, 6~ 3.99,6x 1.22 JAX 7 HZ, OC(HA)~-+ C(Hx)J, and 3.25 (s, NMe,). N-(Dimethyl(2’E)-l’,1’-2H2penta-2’,4‘-dienylarnmonio}-ethoxyformamidide (13f). This was obtained as an oil (75) (Found: M+,200.1495.C10M16D2N202requires M, 200.1493); vmax.1635 cm-’; 6 6.50-6.18 (m, =CH-CH=), 5.84 (d, J 15 Hz, CD,-CWCH), 5.40-5.20 (m, CxCHz), A2XJ system, 6A 4.00,6x 1.24 JAX 7 Hz,OC(H,C(H, and 3.24(s,+ +NMe,), with no detectable signal for the NCH2 group con- sistent with >95 atom D at C-1’.N-{Dimethyl(2’E)-2’-methylpenta-2’,4’-dienylammonio>-ethoxyformamidide (13g). This was obtained as hygroscopic crystals (80) (Found: C, 62.0;H, 9.6;N, 13.5. CllH20N202 requires C, 62.3;H, 9.4;N, 13.2); v,,,,. 1 640cm-’; 6, ABXY system, 6A 6.56,6, 6.16, Sx 5.32, 6y 5.28 (JAB 11, JAx 10, JAY 16 Hz, CHe-CHAHxHy), 4.31 (s, GCH,), A2X3 system, C3A 3.98, 6x 1.21 JAX 7 Hz, OC(HA)ZC(HX)J,3.23 (s, NMe2), and 2.00(s, CXMe).N-(Dimethyl(2’E)-4’-methylpenta-2’,4’-dienylammonio}-ethoxyformamidide (13h). This was obtained as an oil (75) (Found: M+, 212.1528.CllHtaN202requires M, 212.1525); v,,,,.1 640 cm-l; 6, ABXz system, SA 6.48,68 5.77,6x 4.31 JAB 16,JBX 7 HZ, CHA’CHB-C(HX)Z,5.10br (S, C=CHz), AzX3 system, 6A 4.0,6x 1.23 JAX 7 HZ, OC(HA)~C(HX)~I, 3.25 (s, NMe,), and 1.88 (s, CMe).N-{ Dimethyl(2’E)-penta-2’,4’-dienylammonio}methylirreirle(13i).This was obtained as an oil (74) (Found: M+, 183.1376. C9H17N30requires M, 183.1372); v,,,~, 1 590 cm-l; 6 7.50br (NHMe), 6.75-6.20 (m, =CH-CH=), 5.84 (dt, J 15, 7 Hz), 5.50-5.26 (m, CH2), 4.73 (d, J 7 Hz, kH2), 3.67 (s, NMe,), and 2.73 (d, J 5 Hz, MeNHCO). N-{Dimethyl(2’E)-1‘,1‘-zH2penta-2’,4‘-dienylarnmonio}-methylureide (13J). This was obtained as an oiJ (73) (Found: M+, 185.1498. C9HI5D2N30requires M, 185.1497);vmx. 1 590 cm-’; 6 6.77-6.22 (m,‘CH-CH’), 5.84(d, J 15 Hz,+ CDz-CH=CH), 5.51-5.25 (m, C=CH2),3.71 (s, NMez), and 2.76 (d, J 5 Hz, MeNHCO), with no detectable signal for the + NCH2 group consistent with >95 atom D at C-1’.N-{ Dimethyl(2’E)-2’-methylpenta-2’,4’-dienylammonio}-methylirreide (1 3k).This was obtained as an oil (76)(Found : M+, 197.1529. ClOHl9N3Orequires M, 197.1528); vmx. 1 610and 1 550 cm-’; 6, ABXY system, 6, 6.58,6B 6.12, 5.29,Sy 5.25(JAB 10,JAX 16,JAY 10Hz, CHB-CHA=CH,HY), 4.35 (s, kCH,), 3.25 (s, Mez), 2.66(d, J 5 Hz, MeNCHO). and 2.00 (s, C=CMe). N-{Dimethyl(2’E)-4’-methylpenta-2’,4’-dienylammonio}-methylureide (131). This was obtained as an oil (70)(Found: M+, 197.1525. C9H19N30requires M, 197.1528); vmx. 1 595 cm-’; 6, ABXz system, 6A 6.44,6B 5.76,6x 4.34JAB 16, JBX 7 Hz, CHA=CH,-C(HX)Z,5.06 (s, CH2), 3.26 (s, Me2), 2.66 (d,J 5, Hz, MeNHCO), and 1.87(s, =Me).N-(Dimethyl(2’E)-2’-methylpenta-2’,4’-dienylammonio}-phenylureide (13m). This was obtained as crystals (89), m.p. 95-97 “C(Found: C, 69.2;H, 8.1;N, 16.5.C1,H2,N3O requires C, 69.5;H, 8.1;N, 16.2); vmX. 1625 and 1 590 cm-1;6 7.40-7.08 (m,5 aryl H), ABXY system, tiA 6.53, 6B 6.14,6x 5.30,6y 5.25 (JAB 10,JAX 16,JAY 10 Hz, He- + + CHAXHxHy), 4.37 (s, NCH2), 3.24 (s, NMe2), and 2.00 (s, CMe).N-{ DimethyZ(2’E)-4’-methylpenta-2’,4’-dienylammonio}-phenylureide} (13n). This was obtained as crystals (9473,m.p.111-113 “C (Found: C, 69.2;H, 8.3;N, 16.5.C15H2,N30 requires C, 69.5;H, 8.1; N, 16.2); vmx. 1 625 and 1 590 cm-’; 6 7.39-6.74 (m, 5 aryl H), ABXZ system, 6.45,6B 5.78,6x 4.34 JAB 16,JBX 7 HZ, CHAHB-C(H, 5.08br (s, C=CH2),3.27 (s, Me2).and 1.86 (s, CZCMe). N-{ Dimethyl(2‘E)-penta-2’,4‘-dienylammonio}benzamidide(130).This was obtained as an oil (92) (Found: M+, 230. CI4Hl8N20requires M, 230);vmax.1 600, 1565,and 1 558 Cm-’;6 8.00-7.84 (m, 2 ortho-H of C6HS),7.40-7.20 (m, aryl H), 6.50-6.22 (m, =CH-CH=), 5.50 (dt, J 15, 7 Hz, CHXH-CH,), 5.43-5.08 (m,C=CHz), 4.37 (d, J 7 Hz, CH2),and 3.41 (s, kMe2). N-(Dimethyl(2’E)-1’,1’-2H2penta-2’,4’-dienylammonio}-ZH5benzamidide(13p).This was obtained as an oil (94) (Found: C, 70.8;H, 7.9;N,11.85.CI4HllD7N2Orequires C, 70.9;H, 7.6;N, 11.8); v,,,,. 1 580 and 1 535 cm-I ; 6 6.50-6.30(m, H-CH), 5.84(d, J 15 Hz, CH=CH-CD,), 5.50-t 5.15 (m, C=CH2), and 3.36 (s, NMe2), with no detectable + signal for the C6H5group and a low intensity signal for NCH, indicating c‘a.95 atom :L D at C-1’. Thermal Rearrangement of Ammonioamidates ( 13).-The ylide (500 mg) was heated in dry benzene under the conditions specified in Table 1.The product mixtures were separated by preparative t.1.c. on silica. Individual rearrangement pro-ducts were characterised as indicated below. N-{ Dimethyl(2’E)-penta-2’,4’-dienylammonioIacetamidide-(I 3a). This gave 2-acetyl-1,1-dimethyl-2-(2’E)-penta-2’,4’-dienyllhydrazine (143) as an oil (440 mg) which was purified by distillation at 160-162 “C10.1mmHg (Found: C, 64.2;H, 9.3;N, 16.8.C9HI6N2Orequires C, 64.3;H, 9.5;N, 16.7); v,,~,.I 685, 1 600,and I 585 cm-’; 6 6.47-6.03 (m,=CH-CH=), 5.77 (dt, J 14,6 Hz, CH=CH-CH,),5.25-4.98 (m, C=CH,), 3.99 (d, J 6 Hz, NCH2), 2.56 (s, NMe,), and 1.15 (s, COCH3). N-{ Dimethyl(2’E)- 1 ’,1’-2H2penta-2’,4’-dienylammonio}-acetamidide (13b). This gave a 1 : 1 mixture of the l’,l’- 2H2hydrazine derivative (14b) and the 5’,5’-ZH2hydrazine derivative (15b) as a liquid, b.p. 160-165 “C/O.l mmHg (Found: M+, 170. C9H14D2N20 requires M, 170). The distribution of deuterium between positions 1’ and 5’ of the pentadienyl substituent was determined by integration of the n.m.r. spectrum of the l’-Hz and 5’-H2 signals (6 4.01 and 6 5.26-4.96 respectively). N-{Dimethyl(2’E)-2‘-methylpenta-2’,4’-dienylammonio}-acetamidide (13c).This gave a 1 :2 mixture of the 2’-methyl- pentadienylhydrazine (14c) and the 4‘-methylpentadienyl-hydrazine (15c) which could not be separated into its two components (Found: M+, 182.1426. CloHlRN20 requires M, 182.1 419); v,~,,,~.1 650 cm-’ ; 6(2’-methylpentadienylhydrazine) ABXY system, 6, 5.89, 6B 6.54, 6x 5.12, 6y 5.04 (JAB 10, JBX 16, JBy 10 Hz, HA-CHBHxHy), 4.05 (s, NCHZ),2.55 (s, NMe,), 2.20 (s, COCH,), and 1.80 (s, C--CMe);6(4’-methylpentadienylhydrazine) ABX, system, SA 6.26, 6B 5.72, 6x 4.05 JAB 16, JBX 5 HZ, CHA=CHB-C(H, 4.93 (s, C=CH2), 2.55 (s, NMe,), 2.15 (s, COCH,), and 1.80 (s, C‘CMe). The composition of the mixture was based upon the integrated intensities of the COCH, signals (6 2.20 and 2.15).N-{ Dimethyl(2’E)-4’-methylpenta-2’,4’-dienylammonio}-acetamidide (13d). This gave a mixture of the 2’-methyl- pentadienylhydrazine (15d) = (14c)l and the 4’-methyl-pentadienylhydrazine (14d) = (15c)l in the same ratio (1 : 2) as the 2’-methylpentadienylammonioamidide(1 3c). N-{ Dimethyl(2‘E)-pent~-2’,4‘-dienylammonio)ethoxy-formamidide (1 3e). This gave two products. (a) 2-Ethoxy-carbonyl- 1,l -dimethy/-2- (2’E)-pent~-2’,4’-dieny/hydrarirre (14e) (380 mg) as a liquid, b.p. 120-125 “C/12 mmHg (Found: C, 60.3; H, 8.9; N, 14.1. Cl0Hl8NZO2 requires C, 60.6; H, 9.1; N, 14.1); v,,:,,. 1 685 and 1 604 cm-’; 6 6.52-6.02 (m, H-CH=), 5.73 (dt, J 13, 6 Hz, CH=CH-CH2), 5.28-4.98 (m, CH2), AZXJ system, 6A 4.17, 6x 1.27 JAX 7 Hz, OC(HA)2C(Hx)3, 3.94 (d, J 6 Hz, NCH2), and 2 67 (s, NMed.(b) 2-Ethoxycarbonyl-1,l-dimethy/-2-( penta- 1’,4’-dien-3’-yl)-hydruzine (16e) (63 mg) as a liquid (Found: M+, 198.1370. Cl0Hl8N2O2 requires M, 198.1368), v”,,~~.(pure liquid) 1 700 and 1 640 cm-’; 6, AA’XX’YY’Z system, z=6, 6,. 6.02, 6x = 6x. 5.19, Sy = 6y* 5.17, 62 4.92 (JAX = JA*x* 16, JAY = JA*y* 9.5. JAz = JMZ 6.5 Hz, CHxHy= CHA-CH,-CH,‘CHx-Hy*), AZXJ system, 6A 4.19, 6, 1.29 JAX 7 Hz, OC(HA),C(HX),, and 2.71 (s, NMe,).N-( Dimethyl(2’E)- I ’,1’-2H2penta-2’,4‘-dienyl-ammonia )ethoxjforrnamidide ( 13f). This gave two products. (a) A 1 : 1 mixture of the l’,l’-ZHzhydrazine derivative (14f) and the 5’,5’-2H2hydrazine derivative (15f) as a liquid, b.p.120-130 “C/12 mmHg (Found: M+, 200. C10H16D~NL02 requires M, 200). The deuterium distribution between posi- tions 1’ and 5’ of the pentadienyl substituent was determined by integration of the n.m.r. spectrum of the 1’-H2 and 5’-H2 signals (6 3.96 and 6 5.30-4.99 respectively). (b) The l’,l’-zHzhydrazine derivative (16f) as a liquid (Found: M+, 200. C10Ht6D2N202 requires M, 200).N-{ Dimethyl(2’E)-2’methylpenta-2’,4’-dienylammo~io}-rthoxyformamidide (13g). This gave three products. (a) 2-Ethoxycarbonyl-l ,1-dimethyl-2-(2’E)-2’-methyfpenfa-2’,4‘-dieny/hvdrazine (14g) was obtained as a liquid, b.p. 110 “CIO.05 mmHg (130 mg) (Found: C, 62.1; H,9.3; N, 13.5. C11H20NZ02requires C, 62.3; H, 9.4; N, 13.2); v,,,~.1 680 and 1 595 cm-I; 6, ABXY system, 6A 6.54, 6~ 5.95, 6x 5.13, Sy 5.03 (JAB 10, JAX 16, JAY 10 Hz, =CHB-CHA= CHxHy), A2X3 system, 6, 4.15, 6x 1.25 JAX7 Hz, OC(HA)~- C(HX)J, 3.86 (s,NCH2), 2.65 (s,NMe2), and 1.75(s,CMe). J. CHEM. SOC. PERKIN TRANS. I 1983 (b) 2-Ethoxycurbonyl- 1,l -dimethyl-2-( 2’E)-4‘-methylpenta- 2’,4‘-dienyflhydrazine (1 5g) was obtained as a liquid, b.p. 120-122 “C/0.05 mmHg (265 mg) (Found: C, 62.1; H,9.3; N, 13.4. CllHZoN2O2 requires C, 62.3; H, 9.4; N, 13.2); v,,,. 1 680 and 1602 cm-’; 6, ABX2 system, 6, 6.26, 6B5.65, 6x 3.95 JAB 16, JAX 7 Hz, CHA=CHB-C(H~)~, 4.92 (s, C= CHZ), A system, 6A 4.16, 6x 1.26 JAX7 Hz, OC(HJ2- C(Hx),, 2.66 (s, NMe2), and 1.82 (s, C=CMe).(c) 2-Ethoxycurbonyf-1,l-dimethyf-2-(2’-mef~yylpenta-1’,4’-dien-3’-yl)hydruzine (16g) was obtained as a liquid (65 me) (Found : M+, 21 2.1526.CllHtoN20z requires M, 21 2.1525) ; 6, AMNX system, 6~ 6.19, 6~ 5.18, 6~ 5.16, 6x 4.76 (JAM 18, JAN 9, JAx 10 Hz, CHX-CHAXHMHN), 4.92 (s, CHI),A2X3 system, 6~ 4.18, 6x 1.27 JAX7 Hz,OC(HA)ZC(H 2.66 (s, NMe2), and 1.77 (s, CMe). N-{ Dimethyl(2’E)-4’-methylpenta-2’,4’-dienylummo~io}-ethoxyformumidide (1 3h). This gave the 2’-methylpentadienyl- hydrazine (15h) = (14g)(l53 mg), the 4’-methylpentadienyl- hydrazine (14h) = (15g)l (296 mg), and the 2’-methyl-penta-l’,4‘-dien-3’-ylhydrazine(16h) = (1 6g)l (123 mg). N-{ Dimethyl( 2’E)-pent a-2’,4‘-dienylammonio}methylureide (1 3i) gave two products. (a) 1,l-Dimethyl-2-methylcarbamoyl-2-(2‘E)-penta-2’,4‘-dienyllhydruzine (14i) (345 me) was obtained as a liquid, b.p.130-135 “C/O.Ol mmHg (Found: M+, 183.1370. C9H17N30 requires M, 183.1372); v,,,. 3 420 and 1 648 cm-*; 6 6.48-6.04 (m, H-CH=), 5.80 (dt, J 15, 6 Hz,CHH-CHz), 5.20-4.90 (m, CH2), 3.98 (d, J 6 Hz, NCH,), 2.78 (d, J 5 Hz, CONHMe), and 2.48 (s, NMe,). (b) 1,l-Dimethyl-2-methylcarbamoyl-2-(penta-1 ’,4’-dien-3‘- y1)hydrazine (16i) (120 mg) was obtained as crystals, m.p. 65-66 “C (Found: C, 59.3; H, 9.1; N, 22.9. C9H1,N3O requires C, 59.0; H, 9.3; N, 22.95); vmx. 3 420 and 1 650 cm-l; 6, AA’MM‘NN’X system, 6,, = 6,,, 6.31, 6M = 6,. 5.13, 8N = 6” 5.12, 6x 4.33 (JAM = JA’M’ 17.5, JAN =z JA”, 9.5, JAX = JAaX 7 Hz, CHMHNHA-CHX-CHA,=CHM,H~,), 1.78 (d,J 5 Hz, CONHMe), and 1.55 (s, NMe,).N-(Dimethyl(2’E)- 1 ’,1‘-2H2penta-2’,4‘-dienylammonio>-methylureide (13j).This gave two products. (a) A 1 : 1 mixture of the l’,l’-2H2hydrazine derivative (14j) and the 5’,5’-ZHzhydrazine derivative (15j) as a liquid, b.p. 130-135 “C/O.Ol mmHg (Found: M+, 185. C9Hl5DzN3O requires M, 185). The deuterium distribution between posi- tions 1’ and 5’ of the pentadienyl substituent was determined by integration of the C( l’)Hz and C(5’)H2 signals (6 3.98 and 6 5.20-4.90 respectively). (b) The 1’,1’-2H2hydrazine derivative (16j) as crystals, m.p. 64-65 “C (Found: C, 58.9; H, 9.1; N, 22.7; M+, 185. C9Ht5DIN30 requires C,58.4; H, 9.2; N, 22.7; M, 185). N-{Dimethyl(2’E)-2’-methylpenta-2’,4’-dienylammonio}-methylureide (13k).This gave three products. (a) 1,l-Dimethyl-2-methylcarbumoyl-2-(2’E)-2’-methyl-penta-2’,4’-dienylhydrazine(14k) was obtained as an oil, b.p. 115-120 OCl0.02 mmHg (Found: C, 60.2; H, 9.7; N, 21.3. CIoH1,N,O requires C, 60.9; H, 9.7; N, 21.3); vIlIBx. 3 420, 1 650, and 1 525 cm-’; 6 ABXY system, 6, 6.57, 5.97, 6x 5.1 1, 6y 5.05 (JAB 10, JAX 17, JAY 10 Hz, =CHB- CHA=CHxHy), 4.03 (s, NCHZ), 2.82 (d, J 5 Hz, CONHMe), 2.50 (s, NMe,), and 1.81 (s, C’CMe). (b) 1,l-Dimethyl-2-methylcarbamoyl-2-(2’E)-4’-methyf-pent~-2’,4’-dienylhydrazine(1 5k) was obtained as an oil, b.p. 115-120 “C/0.02 mmHg (Found: C, 60.7; H, 9.8; N, 21.5. CloHluN30 requires C, 60.9; H, 9.7; N, 21.3); vIInL 3 420, 1 648, and 1 528 cm-’; 6, ABX2 system, 6, 6.29, 6, 5.77, 6x 4.07 JAB 16, JBX 6 HZ, CHA=CHB-C(HX)~, 4.72 (s,CH2), 2.82 (d, J 5 Hz, CONHMe), 2.50 (s, NMe,), and 1.81 (s, C’CMe).The hydrazines (9k) and (10k) were obtained in a 1 : 2 ratio (356 mg) on the basis of g.c. analysis. J. CHEM. SOC. PERKIN TRANS. I 1983 (c) l,l-Dimethyl-2-methyZcarbamoyl-2-(2’-methyZpenta-1’,4’-dien-3’-yl)hydrazine (16k) was obtained as crystals (95 mg), m.p. 60-61 “C (Found: C, 60.7; H, 9.7; N, 21.1. CloHI9N3O requires C, 60.9; H, 9.7; N, 21.3); vmx. 3 420, 1651, and 1510 cm-’; 6 AMNX system, 6A 6.42, 6M 5.18, 6N 5.11, 6x 4.19 (JAM 10, JAN 18, JAX 8 Hz, CHxCHA= CHMHN), 4.90 (s, C=CH2), 2.75 (d, J 5 Hz, CONHMe), 2.51 (s, NMe,), and 1.77 (s, CMe). N-{DimethyI(2’E)-4’-methylpenta-2’,4‘-dienylammonio}-methylureide (131).This gave the 2’methylpentadienyl-hydrazine (151) =(14k)l and the 4‘-methylpentadienyl-hydrazine (141) =(15k)l (280 mg) in a 1 :2 ratio, and the 3’-(2’-methylpenta-l’,4‘-dienyl)hydrazine (180 mg) (161) = (1WI. N-{Dimethyl(2’E)-2’-methylpenta-2’,4‘-dienylammonio}-phenylureide (1 3m). This gave three products. 1047 was purified by t.1.c. The isotopic composition of the product was determined by mass spectral analysis, based upon peak heights (averaged over several spectra) of the M + ,(A4 -2), (M + 5)+, and (M + 7)+ ions. (b) Determination of relative amounts of 1’,2 and 5’,2 coupling. The rearrangement of the 2H7ammonioamidate (13p) (0.001 mol) was carried out under the conditions sum-marised in Table 2.The ,H,hydrazine derivative (14p) i-(1 5p)I was isolated, and the distribution of deuterium between positions 1’ and 5’ determined by comparison of the intensities of the n.m.r. signals (6 4.11 and 6 5.32-4.93) corresponding to 1’-H2 and 5’-H2. Measurement of Penta- 1 ‘,5‘-dienyl Scrambling in Ammonio-amidates (1 3).-The a.nmonioamidate (1 3) in benzene ( 15 m!) dienyl-2-phenylcarbarnoylhydrazine(14m) and 1,l -dimethyl-2- (2’E)-4’-methylpenta-2’,4‘-dienyl-2-phenylcarbamoyl-hydrazine (15m) (1 :2 ratio) was obtained as a viscous oil (373 mg) which could not be separated into its components by t.1.c. or g.c. (Found: M+, 259. C15HZ1N30 requires M, 259); v,,,. 3 325, 1 665, 1 600, and 1 590 cm-’; for the hydr- azine (14m): 6, 8.67br (s NH), 7.54-6.82 (m, 5 aryl H), ABXY System, 6~ 6.54, 6g 5-95, 6x 5.10, 6y 5.00 (JAB 10, JAX 16, JAY 10 Hz, =CHB-CHA=CHXHY), 4.05 (s, NCH,),2.55 (s, NMe2), and 1.80(s, C=CMe); for the hydrazine (15m): 6, 8.54br (s, NH), 7.54-6.82 (m, 5 aryl H), ABX2 system, 6,6.27,6,5.75,6~ 4.07 JAB 15,JBx 6 Hz, CHAHB-C(HX)~, 4.90 (s, CH2), 2.55 (s, NMe,), and 1.80 (s, CMe).(b) 1,I -Dimethyl-2-(2’-methylpenta-1‘,4‘-dien-3‘-yl)-2-phenyi-carbamoylhydrazine (16m) was obtained as crystals, m.p.77-78 “C (87 mg) (Found: C, 69.6; H, 8.3; N, 16.2. C~NJO requires C, 69.5; H, 8.1; N, 16.2); v,,,,,. 3 360, 1 685, 1608, and 1 595 cm-’; 6,8.57br (s, NH), 7.57-6.90 (m, 5 aryl H), AMNX system, 6n 6.45, 6~ 5.22, 6N 5.16, 6x 4.15 (JAM 18, JAN 10, JAx 8 Hz, CHx-CHA’CHMHp,), 4.94 (s, C‘CH,), 2.60 (s, NMe,), and 1.80 (s, CMe).N-{Dimethyl(2‘E)-4’-methylpent~-2’,4’-dienylammonio}-phenylureide (13n). This gave a mixture of the 2’-methylpent- adienylhydrazine (15n) = (14m)l and the 4‘-methylpentadi- enylhydrazine (14n) 3 (15m)l (I :2 ratio, 345 mg) and the 2’-methylpenta-l’,4’-dien-3’-ylhydrazine (16n) = (16m)l (23). The hydrazine (16n) rearranged when heated in xylene at 138-140 “C for 20 h. The products were separated by t.1.c. to give a 1 :2 mixture of the hydrazines (1) and (14n) (60)and unchanged hydrazine (16n) (20). N-{ Dimethyl(2‘E)-penta-2’,4’-dienylammonio}benzamidide (130). This gave 2-benzoyl-l , 1-dimethyl-2-(2’E)-penta-2’,4’-dienyllhydrazine (140) as an oil, b.p.145-150 “C/0.02 mmHg (460 mg) (Found: C, 72.7; H, 8.1; N, 11.9. Cl4H18N2O requires C, 73.0; H, 7.8; N, 12.2); vmaX.(neat liquid) 1 645, 1 605, and 1 580 cm-’; 6 7.60-7.20 (m, 5 aryl H), 6.54-6.08 (m, =CH-CH=), 6.02-5.72 (m, CH-H-CHJ, 5.32-4.98 (m, CH2), 4.11 (d, J 6 Hz, NCH2), and 2.51 (s, NMe2). Thermal Rearrangement of N-{ Dimethyl( 2’E)-penta-2‘,4’- dienylammonio}benzamidide (1 3o).-(a) Determination of intramolecularity. The rearrangement of a 1 : 1 mixture of the 2Hoammonioamidate (1 30) and the 2H7ammonio-amidate (13p) (0.001 mol) in the specified solvent (5 ml) was carried out under the conditions summarised in Table 2. The reaction mixture was diluted with ether (75 ml) and water (20 ml).The organic layer was separated and evaporated and the residual oil dissolved in hydrochloric acid (20 ml; 10); the acidic solution was washed with ether, made basic (10 aqueous NaOH), and extracted with ether. The ether extract was evaporated to give the rearrangement product (140) which was heated at the temperatures indicated in Table 3. Samples(a) A mixture of 1,l -dimethyl-2-(2’E)-2’-methylpenta-2’,4’-(1 ml) were removed at measured time intervals and eva- porated at room temperature to give a mixture of recovered ylide and rearrangement products. The composition of this mixture was determined by n.m.r. analysis as outlined below. N-{Dimethyl(2’E)-1’,1’-2H2penta-2’,4’-dienylammonio}-2H5benzamidide (1 3p). 1’,5’-Scrambling of the pentadienyl group of the ylide was followed from the increasing intensity + of the NCH2 signal (d, 6 4.36). The rate of rearrangement was t followed by the decreasing intensity of the NMe, signal (s, 6 3.30) of the ylide and the increasing intensity of the NMe, signal (s, 6 2.49) of the rearrangement products (14p) --(15P).N-( Dimethyl(2’E)- 1 ’,1’-2H2penta-2’,4’-dieiienyllarnmonioj -ethoxyformamidide (1 3f).1 ’,Y-Scrambling was followed by + the increasing intensity of the NCH2 signal (d, 6 4.26) of the ylide, isolated from the reaction products by preparative t.1.c. (chloroform-methanol, 9 : 1). The rate of rearrangement was t followed by the decreasing intensity of the NMe2 signal (s,6 3.24) of the ylide and the increasing intensity of the NMe2 signal (s, 6 2.61) of the rearrangement products (14f) (15f) + (16f).N-{Dimethyl(2’E)-2’-methyl~enta-2‘,4‘-die~ylammonic)-acetamidide (1 3c). 1’,5’-Scrambling was followed by the decreasing intensity of the COCH3 signal (s, 6 1.99) of the ylide (13c) and the increasing intensity of the COCHJsignal(s, 6 1.88) of the ylide (13d). The rate of rearrangement was + determined from the decreasing intensity of the NMc, signal (s, 6 3.25) of the ylides (13c) and (13d) and the increasing intensity of the NMe2 signal (s, 6 2.52) of the rearrangement products (14c) + (1 5c). N-{Dimethyl(2’E)-2’-methyl~e~ta-2’,4’-llie~y/am~~~o~~~o1-ethoxyformamidide (1 3g). 1’,5’-Scrambling was followed by the decreasing intensity of the C‘CMe signal (s, 6 2.00) of the ylide (13g) and the increasing intensity of the CXMe signu! (s, 6 1.88) of the ylide (13h).The rate of rearrangement was t determined from the decreasing intensity of the NMe, signal (s, 6 3.23) of the ylides (13g) and (13h) and the increasing intensity of the NMe, signal (s, 6 2.65) of the products (14g) + (15g) + (W.N-{ Dimethyl(2’E)-2’-methylpenta-2’,4’-dienylamm~n~~I-rnethylureide (13k). 1’,5’-Scrambling was followed by the decreasing intensity of the CXMe signal (s, 6 2.00) of the ylide (13k) and the increasing intensity of the C=CMe signai (s, 6 1.87) of the ylide (131). The rate of rearrangemert was i determined from the decreasing intensity of the NMe, signal (s, 6 3.25) of the ylides (13k) and (131) and the increasing intensity of the NMe, signals (s, 6 2.51 and s, 6 2.47) of the products (14k)+ (15k) + (16k). 1048 J.CHEM. SOC. PERKIN TRANS. I 1983 Table 3. Rates of competing 1’,5’-scrambling and rearrangements of the ylides (13c), (13f), (13g), (13k), (13m), and (13p) in benzene Temp. Reaction rates (s’ x 106) I * Ylide (13) R’ R2 R3 X (“c) kt k-1 k2 k3 (13d H Me H Me 80 60 a 150 20 (1 3f) D H H OEt 80 20 20 150 * 150 (13g) H Me H OEt 80 500 a 1600 180 (13k) H Me H NHMe 60 2000 a 6000 220 (13m) H Me H NHPh 40 200 a 80 1 (13P) D H H GD, 80 5h 56 17 17 a Not obtainable from data, assumed to be 0.01 k, since signals assignable to 2’-methylpentadienyl ylides are not detectable after completed 1’,5’-scrambling.For l’,l’-’H2ylides assumed: kl = k-l and k2 = k3. compositions for selected input values of rates, k, k-l, kz,and Me2h-COX Me2fi-iCOX R’ k3 in the reaction scheme outlined below (Scheme 3). The I computation was based upon equations given in ref. 11. WR1 Values of kl, kl,R1* k2 and k3 obtained in this way are of limited accuracy due to the inaccuracy of n.m.r. integrationR2 R3 R3 R2 (estimated error f10 of measured value). kzl k31 References 1 Part 16, K. Chantrapromma, W. D. Oh, and I. 0.Sutherland, J. Chem. SOC.,Perkin Trans. 1, 1983, preceding paper. 2 Part 15, M. Rey, W.D. Ollis, and I. 0. Sutherland, 1. Me,NvCOX + Me2NyCOX R~ 4-Me2NyCOX Chem. SOC.,Perkin Trans. I, 1983, 1009. 3 F. D. Greene, M. A. Berwick, and J.C. Stowell, J. Am. Chem. W R 1 R3~R2 SOC.,1970,92,867; K. R. Kopecky and T. Gillan, Can.J. Chem.,R1h 1969,47,2371; T. Koenig and J. M. Owens, J. Am. Chem. SOC., R2 R3 R3 R2 R’ R’ 1973, 95, 8486; 1974, 96, 4052; M. T. Zoeckler and B. K. Carpenter, J. Am. Chem. SOC.,1981,103,7661. Scheme 3. Competing 1 ’,5’-scrambling and rearrangement of 4 D. Bethel1 and M. R. Brinkman, Adv. Phys. Org. Chem., 1973, ylides (1 3) 10, 53; U. H. Dolling, G. L. Closs, A. H. Cohen, and W. D. Ollis, J. Chem. SOC.,Chem. Commun., 1975, 545. 5 J. F. Garst and C. D. Smith, J. Am. Chem. SOC.,1976,98, 1526. N-{ Dimethyl( 2’E)-2’-methylpenta-2’,4’-dienylammonio}-6 Preliminary communication: K. Chantrapromma, W. D. Ollis, phenylureide (1 3m). 1’,5’-Scrambling was followed by the and I. 0. Sutherland, J. Chem. SOC.,Chem. Commun., 1977, 97.decreasing intensity of the CMe signal (s, 6 2.00) of the 7 R. B. Woodward and R. Hoffmann, Angew. Chem., In?. Ed. ylide (13m) and the increasing intensity of the -Me signal Engl., 1969, 8, 781; M. J. S. Dewar, ibid., 1971, 10, 761. (s, 6 1.86) of the ylide (13n). The rate of rearrangement was 8 K. Chantrapromma, W. D. Ollis, and I. 0.Sutherland, J. Chem.+ SOC.,Chem. Commun., 1978,673.determined from the decreasing intensity of the NMe, signal 9 Part 1, R. W. Jemison, T. Laird, W. D. Ollis, and I. 0. Suther-(s, 6 3.24) of the ylides (13m) and (13n) and the increasing land, J. Chem. SOC.,Perkin Trans. 1, 1980, 1436. intensity of the NMe, signals (s, 6 2.61 and s, 6 2.55) of the 10 H. 0. House and G. H. Ramusson, J, Org. Chem., 1961, 26, products (14rn) + (15m) + (16m). 4278. 11 Z. G. Szabo in ‘ Comprehensive Chemical Kinetics,’ ed. C. H. Determination of Rates of Penta-l’$-dienyl Scrambling and Bamford and C. F. H. Tipper, Elsevier, Amsterdam, 1969, Rates of Rearrangement for the Ylides (13c), (13f), (13g), vol. 2, p. 31. (13k), (13m) and (13p).-The above data for the composition of reactants at measured times were compared with computed Received 26th July 1982;Paper 2/ 127 1