J. CHEM. SOC. PERKIN TRANS. I 1983 945 A 1,3-Rearrangement of Allylic Sulphones Caused by m-Chloroperbenzoic Acid and Sodium Hydrogen Carbonate Philip Kocienski Department of Organic Chemistry, The University, Leeds LS2 9JT The reaction of allylic sulphones with rn-chloroperbenzoic in the presence of aqueous sodium hydrogen carbonate can result in 1,3-allylic rearrangement or isomerisation of the double bond depending on the structure of the allylic sulphone. Subsequent epoxidation then gives P,y-epoxy-sulphones. Epoxidation of allylic sulphones in the absence of sodium hydrogen carbonate gives, p-y-epoxy-sulphones in which the position and stereochemistry of the double bond is retained. A radical-chain mechanism is proposed for the rearrangement reactions. The reductive elimination of a variety of I)-substituted sulphones is a useful procedure for preparing some di-and tri-substituted olefins.'** For example, treatment of the P,y-epoxy-sulphone (2) (Scheme 1) with Na-Hg in THF-Me- OH (THF = tetrahydrofuran) gave a stereoisomeric mixture of the allylic alcohols (3): The P,y-epoxy-sulphones (2) were prepared by epoxidation of the allylic sulphone (1) with rn-chloroperbenzoic acid (m-CPBA) in dichloromethane at room temperature (condition A).However, epoxidation of com-pound (1) with 1.25 equiv. of m-CPBA in the presence of 2.50 equiv. of sodium hydrogen carbonate in aqueous dichloro- methane at room temperature (condition B) gave a 74 yield of a different P,y-epoxy-sulphone whose 'H n.m.r. spectrum I H-doublets at 6 3.61 and 3.00 (J 14 Hz) indicated an iso- lated methylene group adjacent to a sulphone group, consist- ent with structure (4).Control experiments established that the rearranged epoxy-sulphone was formed in the dark and its formation was not catalysed by nz-chlorobenzoic acid. The rearrangement required the presence of both sodium hydro- gencarbonate and rn-CPBA; t-butyl hydroperoxide gave no reaction. The structure of the B,y-epoxy-sulphone (4) was verified by reductive elimination to the known allylic alcohol (5) in 78 yield. Thus, by a minor modification of the reaction conditions, the allylic sulphone (I) could be converted into either of the P,y-epoxy-sulphones (2) or (4). That the rearrangement was general within well defined structural limi- tations was established by examining the epoxidation of the allylic sulphones (6)-(15) under both conditions A and B as summarized in the Table.Under condition A, all the allylic sulphones (6)-(15) behaved normally and no 1,3-rearrangement products were observed. Furthermore, epoxidation was stereospecific in cases (9)-(13) and a single isomer was obtained which retained the position and stereochemistry of the initial double bond. However, clear differences in behaviour were observed under condition B. Sulphones (6) and (7) gave exclusively the products of 1,3-rearrangement and the sul- phone (8)gave a mixture of the rearranged epoxy-sulphone (28) and the unrearranged product (20) in which the rear- ranged product was predominant.In these three cases the arylsulphonyl group migrated from a more to a less substitu- ted carbon. From compound (9), which lacks a methyl group at C-2 of the allylic framework, a mixture of the 1,3-rearranged epoxy-sulphone (26) and the normal product (21) was ob- tained in which the normal product was predominant. Epoxi- dation of the sulphones (10)-(15) under condition B gave no 1,3-rearrangement products despite the presence of the methyl group at C-2 of the allylic framework in the sulphones (lo), (1I), and (1 5). However, epoxidation of compounds (10)- (1 3) was not stereospecific and mixtures of stereoisomeric P,y-epoxy-sulphones were obtained. r-n-c""'vo-n-c6H'wHSO2Ar HI (2) (3 1 n-c6H'+ S02Ar (1 1 5 H OH (4) (5) Scheme 1.Ar = p-tolyl We suggest that sodium rn-chloroperbenzoate can catalyse two related rearrangement reactions of allylic sulphones : I ,3-allylic rearrangement and double-bond isomerisation. A 1,3-migration of an arylsulphonyl group can occur efficiently only when migration can proceed from a more to a less substituted carbon of an allylic framework which bears a substituent at the central carbon (C-2). In allylic sulphones in which the arylsulphonyl group is located on the less substituted carbon atom, stereochemical integrity of the double bond may be lost. Thus the rearranged P,y-epoxy-sulphones were derived from a sequence of reactions in which the starting allylic sulphones first rearrange and then suffer epoxidation. Evi- dence in support of this view was derived from the reaction of the sulphones (7) and (10) with 0.3 equiv.of rn-CPBA in the presence of aqueous sodium hydrogen carbonate. The starting sulphones(7)and (10) were not recovered intact: sulphone (7) had rearranged completely to compound (15) which was iso- lated in 48 yield along with a 22 yield of the epoxy-sul- phone (27), and compound (10) had isomerised to a 4: 1 mixture of compounds (10) and (11) which was isolated in 51 yield along with a 27 yield of a 3 : 1 mixture of the epoxy-sulphones (22) and (23). The foregoing experiments suggest a radical-chain mechan- ism for both the 1,3-allylic rearrangement and the double-bond isomerisation. One possibility is shown in Scheme 2.The pre- cise details of the mechanism require further scrutiny; none- theless the radical nature of the reaction was corroborated by the reaction of the sulphones (7)and (10) with 0.3 eduiv. of nz-CPBA as described above but in the presence of 0.15 equiv. of the radical inhibitor 4,4'-thiobis-(2-t-butyl-6-methyl-phenol). Both the 1,3-allylic rearrangement of compound (7) 946 J. CHEM. SOC. PERKIN TRANS. I 1983 Table Reaction Yield (7) (8) conditions CA) A 87 B 74 A 92 B 55 vSOZAf A 77 (9) B 85 A 86 B 90 A 77 B 73 A 83P+w2Ar B 84 (13) A 72 B 90 A 82 B 52 A B 65FSozAr 71 A 71 (17) B 69 A 85 81WzAr B O*OzAr OVozAf petroleum as developer. Compounds were visualized with 5 (19) (20) in ethanol.Column chromatography was carried out on Kieselgel60 with 10 EtOAc in light petroleum as eluant. 'HN.m.r. data refer to solutions in CDClj at 90 MHz with S02Ar WO, Ar Meamp; as an internal standard. +OzAr Synthesis of the AZZyZic SuZphones.-The allylic sulphones (22 1 (231 (10) and (11); (16): and (17)'O were prepared by reaction of the corresponding allylic chlorides with sodium toluene-p- sulphinate in dimethylformamide. The sulphones (12) l1 and0 (13) were similarly prepared from commerical crotyl bromide bsol;I)bsol;/SOzAr (E:23 :1) using the general procedure described in reference WozArOPSozAr 8. The (E)-isomer (12) was obtained directly by crystallization (24) (25) (26) wrWSozAr (27) (28 1 Ar = p-Tolyl and the double-bond isomerisation of compound (10) were suppressed.Thermal and photochemically induced thioallylic rearrange- ments of allylic aryl thioethers are easy?V6 By contrast the corresponding sulphones are photochemically stable and undergo thermal 1,3-rearrangement slowly only at elevated temperatures.' The experiments reported herein provide a mild and potentially useful rearrangement of allylic sulphones in which a peracid is functioning in an unfamiliar role.Experimental Light petroleum refers to the fraction of b.p. 60-80 "C. Commercial 85 rn-chloroperbenzoic acid was used without further purification. T.1.c. (thin-layer chromatography) was carried out using Kieselgel GF254 with 20 EtOAc in light from light petroleum; the (2)-isomer (13) was isolated by high-pressure liquid chromatography of the mother liquors.The (Z)-isomer (1 3) * had m.p. 56-58 "C;v-. (Ccl4)1 665w, 1 330s, 1 305m, 1 145s, 1 OWm, 91Os, and 685s cm-l; 67.75 and 7.3 (each 2 H, d, J 9 Hz), 5.82 (1 H, dq, J 10.5, J' 7, and J" 1.1 Hz), 5.43 (1 H, dq, J 10.5, J' 8, andJ" 1.8 Hz), 3.82 (2 H, d, J 8 Hz), 2.43 (3 H, s), and 1.37 (3 H, dm, J 7 Hzwith long-range coupling). The allylic sulphone (6) was prepared by methylation of compound (16).9 A second methylation then converted the product (6) into compound (7). A similar tandem alkylation sequence was used to convert compounds (12) and (11) into (9) and (8), respectively. Monoalkylation of compound (17) gave compound (14).The general procedure for all these alkylations is given below. To a stirred 0.2~solution of the allylic sulphone in THF at -78 "C was added dropwise a solution of n-BuLi (1.1 equiv.) in hexane. After being kept for 15 min at -78 "C the solution was treated wtih Me1 (1.5 equiv.; dropwise). The cooling bath was removed and the mixture was allowed to warm to room temperature whereupon brine was added and the organic layer was separated. The aqueous layer was washed with diethyl ether and the combined extracts were washed with * Although a synthesis of this compound has recently been reported,its physical data were not recorded: M. Julia and L. Saussine, Eur. Pat. Appl. 27 421/1981 (Chem. Abstr., 1981,, 204215~). J. CHEM. SOC. PERKIN TRANS.I 1983 + IArS02 I' Ar so (27)( 7) ____c so2amp;qAr -+O I'', Scheme 2 brine, dried (MgS04), and concentrated under reduced pressure. The residue was purified by column chromato- graphy followed by crystallization from light petroleum unless otherwise stated. Yields quoted refer to pure crystalline product. 4-(1 -Hexyf-2-methyfprop-2-enyf)sufphonyftofuene (1). Alkylation of the sulphone (16)with 1-iodohexane as described above gave compound (1) in 80 yield; m.p. 46-48 "C from aqueous MeOH; vmx. (neat) 1 64O'w, 1 315s, 1 305s, 1 290s, 1 145s, 1 085s,and 910 cm-'; 6 7.7 and 7.29 (each 2 H,d, J 9 Hz), 4.95br and 4.65br (each 1 H, s), 3.4 (1 H,dd, J 10 and J' 4 Hz), 2.45 and 1.76 (each 3 H, s), 1.7-2.0 (2 H, m), 1.0-1.4br (8 H), and 0.9 (3 H, distorted t) (Found: C, 68.4;H, 8.9; S, 10.9.C17H2602Srequires C,68.6; H, 8.6;S, 10.7). The following sulphones were similarly prepared. 4-( 1,2- Dirnethyf-prop-2-enyl)sulphonyftofuene (6), 94 from compound (1 6), m.p. 60-64 "C (lit.: 64 "C). 4-(1,1,2-Trimethylprop-2-enyf)-sulphonyftofuene (7), 75 from compound (16), m.p. 64-67 "C; vmX. (CC14) 1 630w, 1 312s, 1 304s, 1 290s, 1 128s, 1 080s,and 910s cm-', 6 7.72 and 7.3 (each 2 H, d, J 9 Hz), 5.lbr and 4.8br (each 1 H, s), and 2.45, 1.95, and 1.52 (each 3 H,s) (Found: C, 65.2;H, 7.6;S, 13.5.C13Hle02S requires C, 65.5; H, 7.6; S, 13.45). 4-(E)-(1,1,2-Trimethyfbut-2-eny1)sulphonyfltofuene (8), 60 from compound (12), m.p.50-51 "C;vmX. (cc14) 1 ~OOS,1 290s, 1 155~,1 145~,1 125~, 1 OSOs, 820m, and 680s cm-'; 6 7.65 and 7.25 (each 2 H,d, J 8 Hz), 5.3 (1 H, q with fine splitting, J7 Hz), 2.43 (3 H, s), 1.78 (3 H,q, J 1 Hz),1.55 (3 H, d with fine splitting, J 7 Hz), and 1.48 (6 H, s) (Found: C, 66.4;H, 7.7; S, 12.7.CI4HzoO2S requires C, 66.63;H, 8.0;S, 12.7). 4-(E)-(l,l-Dimerhyfbur-2-enyf)sufphonyltolene (9), 80 from compound (1 2), m.p. 43-45 "C;vmX. (CCls) 1 310s, 1 3OOs, 1 290m,1 16Os, 1 125s, 1 08Os,and 680scm-'; 6 7.6and 7.3 (each 2 H, d, J 9 Hz),5.5-5.65 (2H,m), 2.45 (3 H, s), 1.7 (3 H, d, J6 Hz), and 1.4 (6 H, s) (Found: C, 65.5;H, 7.5; S, 13.2. C13HlsOzS requires C, 65.5; H, 7.6; S, 13.45). 4-(I,3-Dimethyfbu?-2-enyf)suf-phonyftofuene (14), 81 from compound (17),m.p. 71 .O-71.5 "C; vmX. (neat) 1 305s, 1 290s, 1 14 1090m, 820m, 725s,and 660s cm-'; 6 7.72 and 7.3 (each 2 H,d, J 9 Hz), 5.0 (1 H,dq, J11 andJ'1 Hz),3.85 (1 H,dq, J11 andJ'6Hz),2.44(3 H,s), 1.68 (3 H,s), 1.41 (3 H, d, J6 Hz), and 1.3 (3 H, d, J 1 Hz)(Found: C, 65.2;H, 7.5;S,13.3.Cl3Hl8O2Srequires C, 65.5;H, 7.6;S, 13.45). 4-(2,3-Dimethyfbut-2-enyZ)sufphonyfJ-toluene (15), m.p. 63-65 "C, vmX. (CCl,) 1 322s, 1 305m, 1 145s,and 1 090m cm-'; 6 7.75 and 7.34(each 2 H, d J9 Hz),3.86 (2 H, s) and 2.46, 1.78, 1.66, and 1.33 (each 3 H,s) (Found: C, 65.3;H, 7.6;S,13.2.C13H1802Srequires C,65.5; H, 7.6;S, 13.45). General Procedure for Epoxidation.-Condition A. A solu- tion of the allylic sulphone (1.0 mmol) and m-CPBA (1.1 mmol) in CH2C12 (3 cm3) was stirred at room temperature until t.1.c.indicated complete consumption of starting ma- terial. The reaction mixture was diluted with diethyl ether (20 cm3) and was extracted successively with 10 cm3 portions of saturated aqueous NaHS04, NaHC03, and NaC1. The organic layer was dried (MgS04) and concentrated under reduced pressure. The crude product in diethyl ether solution was filtered through a 1 cm plug of Kieselgel to remove polar, coloured impurities. The residue obtained on evaporation of the filtrate was crystallized from diethyl ether-light petroleum. Yields quoted in the table refer to recrystallized products un- less otherwise stated. Condition B. To a rapidly stirred mixture of the allylic sulphone (1.0 mmol) in CHzClz (3 cm3) and NaHC03 (2.5 mmol) in water (3 cm3)was added, in one portion, m-CPBA (1.25 mmol).The mixture was stirred at room temperature until t.1.c. indicated complete consumption of starting material. The residue obtained after aqueous work-up as described above was purified by column chromatography. With the sulphones (l), (a), and (8)-(13) a mixture of epoxy-sulphone products was obtained which could not be resolved by column chromatography; in these cases the isomeric composition was determined by 'H n.m.r. spectroscopy. In these cases the yields quoted in the Table refer to the chromatographically purified mixture. (2SR)-2-Methyl-2-(1 SR)-1-(p-tofylsulphonyl)he~ty~oxiran and (2SR)-2-Methyf-2-(1 RS)-1-(p-tofyfsufphonyl)heptyloxi-ran (2).A 2: 1 mixture of isomers was obtained which was separated by column chromatography. The major isomer had m.p. 58-60 "C;vmX. (CC14)1 325s,1 305s,1 150s, and 1 090s cm-I ;6 7.82 and 7.38 (each 2 H, d, J 9 Hz), 2.58 (1 H, dd, J 10, J' 8 Hz), 2.48 and 1.44(each 3 H, s), 2.46 and 2.35 (each 1 H, d, J 5 Hz), 1.8-2.2 (2 H, m), 1.28br (8 H), and 0.87 (3 H, dis- torted t) (Found: c,65.7;H, 8.3;S, 10.0.CI7Hz6O3Srequires C, 65.8;H, 8.4;S, 10.3). The minor isomer (oil, very similar i.r. spectrum) showed 6 7.75 and 7.3 (each 2 H,d, J9 Hz), 2.83 (2 H, m), 2.61 and 2.41 (each 1 H, d, J 5 Hz), and 2.42 and 1.40 (each 3 H,s). The following oxirans were also prepared. cis-and trans-3-Hexyf-2-methyf-2-(p-tofyfsufphonyfmethyf)-oxiran (4). An inseparable mixture of cis and trans isomers was obtained (1 :4).The major (presumably trans) isomer showed 6 7.85 and 7.42 (each 2 H, d, J 9 Hz), 3.61 and 3.0 (each 1 H, d, J 13.5 Hz, CHzS02), 2.8 (1 H, distorted t, J 6 Hz, HCO), 2.45 (3 H, s), 1.45 (3 H,s), 1.1-1.6br (10H),and 0.88 (3 H, distorted t). The minor isomer showed 6 7.87 and 7.42 (each2 H, d, J 9 Hz), 3.47and 3.25(each 1 H, d, J 13.5 Hz, CHzSO2), 2.45 (3 H, s), and 1.55 (3 H, s). (2SR)-2-Methyf-2-(1SR)-l-(p-tofyfsuZphonyf)ethyloxiran and (2SR)-2-Methyf-2-(1 RS)-l(p-rofyfsulphonyZ)ethyfoxir~n(18). A 3 :1 mixture of isomers was obtained and was separated by column chromatography. The major isomer had m.p. 72-73 "C; vmX, (CC14)1 325s,1 305m and 1 150scm-'; 6 7.75and 7.35(each 2H, d, J 9 Hz), 2.66 (1 H, q, J7Hz), 2.63and 2.5(each 1 H, d, J3Hz), 2.45(3 H, s), 1.46(3 H, d, J 7 Hz), and 1.44(3 H, s) (Found: C, 60.0; H, 6.7;S, 13.1.Cl2HI6O3Srequires C, 60.0;H, 6.7;S, 13.3). The minor isomer (oil) showed vmax,(CCl,) 1320s,1305s, 1 290sand 1 150scm-'; 6 7.75and 7.35(each 2H, d, J8 Hz),3.08(1 H, q, J8 Hz), 2.6and 2.55(each 1 H, d, J4.5Hz), 2.44 and 1.51(each 3H, s), and 1.28(3 H, d, J8 Hz).2-Methyl-2-1-methyl-I -(p-tolylsulphonyl)ethyloxiran(1 9),m.p. 60-63 "C ; vnlax.(CCI,) 1 370m,1 315s, 1 305s, 1 290m,1 150s, 1 125s, 1 080m,and 1 070m cm-' ;6 7.72and 7.32(each 2H, d, J8 Hz), 2.62and 2.45(each 1 H, d, J4Hz), and 2.42,1.53,1.42,and 1.08(each 3 H, s) (Found: C, 61.1;H, 6.9;S, 12.4.C13H1803S requires C, 61.4;H, 7.1; S, 12.6).trans-2,3-Dimethyl-2-l -methyl-1-(p-tolylsulphonyl)ethyloxiran (20), m.p. 71- 72"C; vmax,(CCl,) 1 315s,1 305s,1 290m,1 135s,and 1 080s cm-'; 6 7.85and 7.3(each 2H, d, J9Hz), 2.9(1 H, q, J6Hz),2.48and 1.13(each 3 H, s), 1.51 (6 H, s), 1.22(3 H, d, J6Hz) (Found: C, 62.3;H, 7.2;S, 11.6.C14HZ003Srequires C, 62.65;H, 7.5;S, 11.95). trans-2-Methyl-3-l-methyl-l-(p-tolylsulphanyl)ethyloxiran (21),m.p. 63-65 "C; vmaX.(CCI,)1 305s,1 290s,1 170m,1 14Os,and 1080scm-'; 6 7.85and 7.3(each 2H, d, J9Hz), 3.05(1 H, d, J2.5Hz), 2.72(1 H, dq, J 6 and J' 2.5 Hz), 2.48, 1.33, and 1.24(each 3 H, s), and 1.28 (3 H, d, J6Hz) (Found: C, 61.4;H, 7.0;S, 12.8.Cl3HI8O3S requires C, 61.4;H, 7.1; S, 12.6). cis-2,3-Dimethyl-2-(p-tolylsuIphonyfmethyl)oxiran(22), m.p.67-68 "C;vmaX.(eel,) 1 330s,1 305m, 1 150s,and 1 090mcm-'; 6 7.8and 7.35(each 2 H, d, J 9Hz), 3.42and 3.18 (each 1 H, d, J14Hz), 2.88(1 H, q, J 6Hz), 2.43and 1.53(each 3H, s), and I .13(3H, d, J 6 Hz) (Found: C, 59.8:H, 6.5;S, 13.5. Cl2Hl6o3S requires C, 60.0; H, 6.7;S, 13.3). trans-2,3-Dimethyl-2-(p-tolylsulphonyl-methyl)oxiran (23), m.p. 52-54 "C; vmaX.(CCl,) 1 330s,1 305-m,1 16Os,1 140s,and 1 090mcm-'; 6 7.76and 7.35(each 2H, d, J9Hz), 3.55 and 2.93(each 1 H, d, J14Hz), 2.73(1 H, q, J 6Hz), 2.43and 1.43(each 3 H, s), and 1.17(3 H, d, J 6Hz) (Found: C, 60.2;H, 6.6;S, 13.3.Cl2Hl6O3S requires C, 60.0;H, 6.7;S, 13.3). trans-2-Methyl-3-(p-tolylsulphonyl-methy1)oxiran (24), m.p. 49-53 "C; vmax. (eel,) 1 330s, 1 310m,and 1 155scm-'; 6 7.82and 7.35(each 2H, d, J9Hz),3.2-3.5 (2 H, m, CH2S02), 3.0(1 H, dd, J 6.3, J'4.8, and J" 1.8Hz), 2.65(1 H, qd, J 5.2 and J' 1.8 Hz), 2.46(3 H, s), and 1.24(3 H, d, J5.2Hz) (Found: C, 58.0; H, 6.3;S, 13.9.CllH14-0,s requires C, 58.4;H, 6.2;S, 14.2).cis-2-Methyl-3-(~- tolylsulphony1methyl)oxiran (25), m.p. 53-56 "C; vmas.(CCI,)1 330s,1 310m,1 155s,1 135m,1 090m, and 895m cm-'; 6 7.82 and 7.35(each 2H, d, J9Hz), 2.9-3.35 (3H, m), 2.45(3 H, s), and 1.08(3H, d, J 5.4 Hz) (Found: C, 57.9;H, 6.1;S, 14.0. J. CHEM. SOC. PERKIN TRANS. I 1983 Cl1Hl4O3S requires C, 58.4;H, 6.3;S, 14.2). 2,2-Dimethyl- 3-l-(p-tolylsulphonyl)ethyloxir~n(26). A single isomer of unknown relative stereochemistry was obtained directly by crystallization, m.p.67-70 "C; vmax.(CCI,) 1 380m, 1 330s, and 1 320scm-'; 6 7.72and 7.34(each 2H, d, J8 Hz), 2.7-3.05(2H,m, OCHCHMe3), 2.43(3 H, s), 1.43-1.6 (3 H, m, OCHCHMe), and 1.16and 0.78(each 3H, s) (Found: C, 61.1; H,7.0;S, 12.5.CI3Hl8O3Srequires C, 61.4;H, 7.1; S, 12.6). 2,2,3-Trinzethyl-3-(p-tolylsu1phonyImethyl)oxiran (27), m.p.60-62 "C; v~,,:~~.(neat) 1 315s, 1 305s, 1 290m,and 1 145s cm-'; 6 7.72and 7.24(each 2 H, d, J 9 Hz), 3.43and 3.13 (each 1 H, d, J14Hz), and 2.38, 1.48, 1.2, and 1.07(each 3 H, s) (Found: C, 61.3;H, 6.9;S, 12.8.C13H1803S requires C, 61.4;H, 7.1;S, 12.6). 2,2,3-Trimethyl-3-l-(p-tolylsulphonyl)-ethylloxiran (28), m.p. 83-85 "C; vmax.(CCI,) 1 320s,1 305s, 1 290m,1 155s,1 090m,and 650scm-'; 6 7.75and 7.35(each 2H, d, J9Hz), 3.1(1 H, q, J7Hz), 1.49, 1.32, and 1.22(each3 H, s), and 1.42(3 H, d, J7Hz) (Found: C, 62.3;H, 7.7;S.11.7.Cl4HZ0O3Srequires C, 62.65;H, 7.5;S, 11.95 Acknowledgements Helpful discussions with Dr. David W. Jones and Dr. Andrew Feiring are gratefully acknowledged. We thank Mr. R. S. B Jones for some preliminary experiments. References 1 B. Lythgoe, Chem. SOC. Rev., 1981, 10,449. 2 P. J. Kocienski, Chem. Znd. (London), 1981, 548. 3 P. J. Kocienski, Tetrahedron Lett.,1979, 441. 4 J. A. Katzenellenbogen and K. J. Christy, J. Org. Chem., 1974, 39, 3315. 5 P. Brownbridge and S. Warren, J. Chem. Soc., Perkin Trans. I, 1976, 2125. 6 A. P. Kozikowski, E. M. Huie, and J. P. Springer, J. Am. Chem. SOC.,1982, 104, 2059. 7 R. D. Baechler, P. Bentley, L. Deuring, and S. Fisk, Tetrahedron Lett.,1982, 23, 2269. 8 P. J. Kocienski, B. Lythgoe, and I. Waterhouse, J. Chem. SOC., Perkin Trans. I, 1980, 1045. 9 K. Koosha, J. Berlan, M. L. Capmau, and W. Chodkiewics, Bull. SOC. Chim. Fr., 1975, 1284. 10 F. G. Bordwell and T. G. Mecca, J. Am. Chem. SOC., 1972,94, 5829. 11 R. Moreau, Y. Adam, and P. Loiseau, C. R. Hebd. Skances Acad. Sci., Ser. C, 1978, 287(2), 39. Received 2nd August 1982; Paper 211 332
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