J. CHEM. SOC. PERKIN TRANS. I 1983 Steroidal N-Nitro-amines. Part 2.1 Denitroamination of Steroidal 12p-,17p-, 2Op-, and 23R-Nitro-amines Cosme G. Francisco, Raimundo Freire, Rosendo Hernhdez, Daniel Melih, Jose A. Salazar, and Ernest0 SuArez * lnstituto de Productos Naturales Orginicos, C.S.I.C.and Departamento de Quirnica Orgdnica,Universidadde La Laguna, La Laguna, Tenerife, Spain 20p-Nitroaminopregn-5-en-3p-ylacetate (1 3a), 17~-nitroamino-5a-androstan-3~-ylacetate (1 4), and 12p-nitroamino-(25R)-5a-spirostan-3p-yl acetate (I 5a) have been prepared by nitrosation of the cor- responding oximes, followed by reduction with sodium borohydride. The 23-nitro-imine (1 2), obtained by reaction of sarsasapogenin acetate (1 0) with nitrous acid and boron trifluoride-diethyl ether complex, was similarly reduced to give 23R-nitroamino- (2OS,22Sr25S) -5p-spirostan-3p-yl acetate (1 6).Denitroamination of (13a) was achieved by treatment with acetic anhydride and pyridine to give the acetates of pregna-5,20-dien-3P-ol (1 7), pregn-5-ene-3p,20B-diol (I 8), 17a-methyl-o-homo-androst-5-ene-3,17ap-diol (1 9),and 17a-methyl-I 2a-methylene-c(l2a)-homo-l8-norandrost-5-en-3~-ol(20).Under the same conditions the nitro-amine (14) afforded the acetates of 5a-androst-I 6-en-3P-01 (27a), 17P-methyl-? 8-nor-5a-androst-I 2-en-3p-01 (28a), 17-methyl-I 8-nor-5a-androst-l3(17) -en-3p-ol (29a), and 17p-methyl-? 8-nor-5a-androst-I 3-en-38-01 (30a). Denitroamination of (1 5a) took place through the expected C-nOr-D-hOmO rearrangement producing 14(13 --+ 12aH)abeo-(25R)-5a-spirost-13(18)-en-31)-yl acetate (31) in high yield and a minor amount of 14(13 -12)abeo-(25R)-5a-spirost-12-en-3p-yl acetate (32).The transstereochemistry of the P-hydrogen-elimination produced in the denitroamination of (1 6) was established by using labelled sarsasapogenin (1 0) biosynthesized by Agave attenuata from 2-l 4C,(4R) -4-3H mevalonic acid. In a preceding paper we reported the denitroamination of 4p-, 6p-, 7a-, and 7P-steroidal nitro-amines by treatment with acetic anhydride and pyridine. An ion pair mechanism, similar to that currently accepted for the deamination of alkyl primary amines with nitrous acid,2 was proposed as shown in Scheme 1. The observed denitroamination products were olefins produced by a @-elimination process, acetates by substitution for the counter ion, and, in the case of a-hydroxy-nitro-amines, oxirans by intramolecular nucleophilic substitution.The purpose of the study reported herein was to examine the denitroamination reactions of steroidal nitro-amines in positions 12p-, 20p-, and 17p- of the steroid skeleton in order to compare them with the behaviour of other functional groups in the same positions that are able to generate carbo- cations, e.g. nitrous acid deamination of amines? solvolysis and pyrolysis of tosylate~,~~.~ mesylates,3u and sulphates; and dehydration of alc~hols.~~*~ The major products of these reactions are, in general, Wagner-Meerwein type rearranged compounds.We also report the stereochemistry of the p-hydrogen elimination reaction during the denitroamination of the axial 23-nitro-amine (1 6). Results and Discussion Preparation of the Substrateu.-20-N itroiminopregn-5-en-3p-yl acetate (3) was conveniently prepared (78) by nitros- ation ’of the corresponding oxime (2) with sodium nitrite in methylene chloride-acetic acid. Its i.r. spectrum shows bands characteristic of the nitro-imine group at 1 620 (GN) and 1 580 and 1 315 cm-I (NO2). In a similar way 17-nitroimino- 5a-androstan-3P-yl acetate (6) and 12-nitroimino-(25R)-5a- spirostan-3P-yl acetate (9) were synthesized in 26 and 98 yield, respectively, the analytical and spectroscopic data being in accord with the proposed structures; the low yield observed for the nitro-imine (6) was due to hydrolysis to the ketone (4) (65) during the reaction.Treatment of (25S)-SP-P 0Ac Scheme 1 spirostan-38-yl acetate (sarsasapogenin acetate) (1 0) with sodium nitrite in acetic acid and boron trifluoride-diethyl ether complex led 9a*b to a mixture of 23-oxosarsasapogenin acetate (1 1) (1 5) and 23-nitroiminosarsasapogeninacetate (12) (51). The mass spectrum of (12), which shows the expected fragment corresponding to M+ -NOz (m/z 470, 3373, has a typical fragmentation pattern of spirostan sapogenin with an electronegative substituent at (2-23 9b*c (see Experimental section); its i.r. spectrum exhibits absorptions at 1 644 (GN) and 1 575 and 1 318 cm-’ (NO,). Chemical evidence for this structure was obtained by hydrolysis of (12) with neutral aluminium oxide (activity IIJ) to give quantit- atively the ketone (1 1).The reduction * of the nitro-imines (3), (6), (9), and (12) with sodium borohydride in ethanol at room temperature led to 2OP-nitroaminopregn-5-en-3P-ylacetate (1 3a) (90), 17~-nitroamin0-5a-androstan-3P-ylacetate (14a) (75), 128- nitroamino-(25R)-5a-spirostan-3~-ylacetate (15a) (65),t and 23R-nitroamin0-(20S,22S,25S)-5P-spirostan-3~-~1acetate (16) (95).The nitro-amine (13a) shows i.r. bands at 3 370 and 3 240 (NH) and 1 580 cm-I (NO2); in its n.m.r. spectrum the amine proton and the 20-H are observed as multiplets at 6 9.2 and 4.2, respectively. The presence of the nitro-amine group can be confirmed by its mass spectrum, where fragments correspond- ing to M+ -NOz and M+ -NHzNOz are observed.The t The 12a-axial isomeric nitro-amine (1Sb) (64.42 (m, W,10 Hz, 12B-H)is also formed in 16 yield. 298 J. CHEM. SOC. PERKIN TRANS. I 1983 R H (1 1 R = O,R'=OAc (41 R =o,R'=oA~ (2)R=NOH,R'=OAc (5) R =NOH,R'=OAc ( 3 1 R = NNO*,R'=OAc ( 6 1 R = "02, R'= OAC (13a) R = a -H, p -NHN02, R'= OAc (1lal R = a -H, p -NHN02 ,R' = OAc (13b) R= a-H,p-NHN02,R'=OH (llb) R = a -H, p -NHN02 ,R'= OH (71 R=O (81 R=NOH ( 9 1 R = "02 (15a) R = a -H, p -NHN02 (15b) R = p -H, a -NHN02 Scheme 2 (2-20 stereochemistry in (13a) was assumed to be R * by analogy with 20~-alcohols obtained almost exclusively by sodium borohydride reduction of 20-0xopregnanes.~~The structures of the other steroidal nitro-amines (14a), (15a), and (16) were established in a similar way.The P-configuration of the nitro-amine group in (14a) and (15a) was determined by the shape of the signal corresponding to the geminal protons in their n.m.r. spectra which appear, after exchange of the amine protons with deuterium oxide, as a triplet at 6 4.05 (J 6 Hz) and a broad multiplet at 4.0 (W, 24 Hz), respectively. The same forms of the signals are observed in the n.m.r. spectra of 17P- and 12P-hydro~y-steroids.~~ The 23a-H signal in the n.m.r. spectrum of (16) could be observed without overlapping with C-3 and C-16 protons, using a 240 MHz apparatus; this appears, after irradiation of the amine proton, as a narrow multiplet at 6 4.27 (W,14 Hz) as expected for the 23-axial configuration of the nitro-amine group.Denitroamination Reactions.-The denitroaminations were accomplished, at room temperature, by treatment of the nitro- amines with acetic anhydride and pyridine for 12 h. Nitrogen- bearing compounds were not isolated from these reactions. The observed products can be conveniently explained by an ion pair mechanism as shown in Scheme 1. The 20P-nitro-amine (1 3a) yielded under these conditions the olefin (17) (26) l3 produced by P-hydrogen-elimination,? the 20P-acetate (18) (16) l5 coming from substitution by the counter ion with total retention of configuration, and the * To confirm its 20R-stereochemistry, the 20s-isomer of (1 3b) m.p.238-240 "C (acetone-n-hexane), 6 (2Hspyridine)0.7 1 (13-Me), 1.03 (10-Me), and 1.35 (20-Me) was synthesized bynitration with ethyl nitrate of the lithium salt of 20s-aminopregn-5-en-3P-01.'~~ Wagner-Meerwein rearranged compounds (19) (22) l6 and (20) (6). The rearrangement that produces the D-homo- compounds (uranediol rearrangement) is common in the heterolysis of other 20P-steroid derivatives 4bs due to the highly favourable conformational situation l7 of the side chain in these substances. The structure of the c-homo- compound (20) is tentatively assigned by spectroscopic data ; from its high-resolution mass spectrum a C23H3402 mole- cular formula can be deduced, and the principal fragments agree with this structure.The presence of an exocyclic double bond can be deduced by i.r. absorptions at 3 090 and 890 cm-I and by two broad singlets at 6 4.89 and 4.70 in the n.m.r. spectrum. The methyl groups are observed at 6 1.14 (s, 10-Me) and 0.99 (d, J 7 Hz, 17-Me). This compound (20) pro- bably arose from migration of the C( 16)-C( 17) bond to C-20 and formation of the carbonium ion (23) (Scheme 4) which can be stabilized by addition of acetate anion (path a) to give (19) or by migration of the C(13)-C(14) bond and loss of a hydrogen from C-18 to give (20) (path b). A carbonium ion like (24) has been postulated by Hirschmann 4a as an inter- mediate during the formolysis of 20P-tosyloxypregnane to explain the formation of epimeric compounds at C-13, C-17, and C-17a during the uranediol rearrangement.In our case, the absence of epimers of (19) indicates that the carbonium ion (24) is preferentially base stabilized by the loss of a C-18 hydrogen to give (20). During the nitrous acid deamination the 20P-aminopregnane behaves differently from the 20P-nitro-amine (1 3a) giving, almost exclusively, transposition products of the D-homo-androstane type; no substitution products such as compound (18) were observed.3b t In one case a small amount of isomerized E-olefin (21) l4 was obtained (1.5). J. CHEM. SOC. PERKIN TRANS. I 1983 OAc R CI H 4 (17) (181 (25) (26) OAc 54fJ 5 4 (20) (211 (27) (28) a; R =OAc b;R=OH Scheme 3 ‘qq‘s 5 4 (29) 5dI5 (30) a; R = OAc b; R= OH (24) (19 1 Scheme 4 Three types of reaction are involved in the denitroamin- ation of the 17p-nitro-amine (14a): (i) substitution is the predominant path (46), products (25a) and (26a) being obtained with 65 of invertion of configuration at C-17; (ii) a p-elimination reaction to give the olefin (27a) (13); and (iii) the 1,Zmethyl-shift rearranged compounds (28a) (9), (29a) (lo),and (30a) (10).The n.m.r. spectrum of the previously undescribed olefin (28a) shows an angular methyl group at 6 0.79, a methyl doublet at 6 1.00 (J7 Hz),and a vinyl proton at 6 5.3. The rearranged olefins (28a), (29a), and (30a) are the expected products from a C-17 carbonium ion, e.g. the solvolysis of 17p-t0sylates,’~ the acid- catalyzed dehydration of the 17fi-al~ohoIs,~ and the elimin- ation of a 17P-benzamide.19 In all these reactions a mixture of olefins was obtained containing the isomer as the main product, with lesser amounts of A13 and other isomeric olefins.The olefin (27a), which has not been detected in the aforementioned reactions, probably arose through a p-elimination via an ion pair mechanism. In contrast with the denitroamination reaction, the nitrous acid deamination of 17P-amines3c gave the 17p-alcohol exclusively and quantita- tively with total retention of configuration. The denitroamination of the 12P-nitro-amine (1 5a) affords almost quantitatively the rearranged c-nor-D-homo-com-Scheme 5 H .. AcO (311 5 (321 Scheme 6 pounds (31) (95) and (32) (5).The high yield of the kinetic exocyclic olefin is in agreement 3a with the decomposition of the 12P-tosylate of rockogenin acetate in refluxing pyridine (em:endo 90: 10) and in contrast with the nitrous acid deamination of 12p-amines (exo :endo 22 :78).* The reaction of the 23R-nitro-amine (16) with acetic anhydride and pyridine gave the 23-dehydrosarsasapogenin acetate (34) in 95 yield; no substitution products are formed in agreement with the axial configuration of the nitro- amine.’ This olefin (34) has been previously obtained by pyrolytic elimination of the 23s-phenylselenoxide of sar-sasapogenin acetate.*O We have reported zo that the satsa- *In the solvolysis of different 12P-substituted steroids 3cr the ratio exo to endo olefins has been reported to be highly dependent on the solvent and the reaction conditions.300 J. CHEM. SOC. PERKIN TRANS. I 1983 Table. 'H N.m.r. data (6 in CDC13)(J/Hz or W,/Hz in parentheses) 17-H 20-H 5.1 (m,20) 23-H 26-H 3.43 (m, 15)3.43 (m,18)3.42 (m, 18)3.5 (m, 15)3.53 (m, 12)4.13, 3.38 (ABX, 12) 4.27 4.09, (m, 18) 3.39 (ABX, 12) 6.04, 4.07, 5.54 3.48 (ABX, 10) (ABX, 11) a 20- =CH2. * 17aa-H. '' 17-Me. ' 12a- =CH2. 16-H and 17-H. 17P-Me. 13- =CH,. * 24-H and 23-H. sapogenin, biosynthesized by Agave attenuatu Solm (Aga- vaceae) from 2-14C, (4R)-4-3Hmevalonic acid, has a B-equatorial tritium atom at C-24; this allowed us to study the stereochemistry of this P-hydrogen elimination.So, the labelled 23R-nitroaminosarsasapogeninacetate ( 16) (specific activity 1.63 x lo5 d.p.m. rnmol-' of "C, and atomic ratio 3H/14C2.01/5) was denitroaminated to give the olefin (34) (specific activity 1.60 x lo5 d.p.m. mmol-' of I4C, atomic ratio 3H/14C 1.9515) in which the 3H-C24 remains. Hence, we conclude that the denitroamination reaction of the axial 23- nitro-amine (1 6) is mainly a solvent-induced trans-elimination as shown in (33). Similar results have been obtained for the deamination of primary amines in basic soIvents.21 Experimental M.p.s were determined with a Kofler hot-stage apparatus and are uncorrected. Optical rotations were measured for solutions in CHC13.1.r. spectra were taken on a Perkin-Elmer 257 instrument.'H N.m.r. spectra were recorded with a Perkin-Elmer R-12B (60 MHz), Perkin-Elmer R-32 (90 MHz) or I.E.F. (240 MHz) instruments and 13Cn.m.r. spectra on a Varian C.F.T.-20 (20 MHz) instrument for solutions in CDC13 with MeSi as internal reference. Low- and high-resolution mass spectra were determined with a VG Micromass ZAB-2F spectrometer. 14Cand 3H Labelled compounds were measured in a liquid scintillation counter Nuclear Chicago Isocap-300. T.1.c. was run on Merck silica gel 60, and column chromato- graphy on Merck silica gel 0.063-0.2 mm. The spray reagent for t.1.c. was H2S04-AcOH-H,0 (1 : 20 : 4) or vanillin (1 g)-H2S04 (160 ml)-EtOH (40 ml). 20-Nitroiminopregn-5-en-3B-yl Acetate (3).-To a solution of 20-oxopregn-5-en-3B-yl acetate (1) (1 g) in dry pyridine (10 ml), hydroxylamine hydrochloride (0.5 g) was added, and the mixture was stirred at 60 "C for 3 h.After addition of water the mixture was extracted with ethyl acetate and the organic solution was washed with aqueous hydrochloric acid J. CHEM. SOC. PERKIN TRANS. I 1983 Ac 0 H (16) H (34) Scheme 7 (lo), saturated aqueous sodium hydrogen carbonate and water, dried (Na2S0,), and evaporated under reduced pres- sure, to give the oxime (2) (0.98 g), which was used without purification in the next reaction. To the oxime (2) (0.72 g), dissolved in methylene chloride (34 ml) containing sodium nitrite (0.82 g), a mixture of acetic acid (1.2 ml) and methylene chloride (70 ml) was added dropwise at room temperature during 5 h. The mixture was then poured into water and extracted with diethyl ether.Work-up and column chromato- graphy (benzene-ethyl acetate 99: 1 as eluant) gave 20-nitroiminopregn-5-en-3P-ylacetate (3) (0.6 g), which crystal- lized from acetone-n-hexane, m.p. 175-176 "C, .ID -21" (c 0.23) (Found: C, 68.4; H, 8.5; N, 6.8. CZ3H34N2O4 requires C, 68.6; H, 8.5; N, 6.95); m/z 342 (2, M+ -AcOH), 327 (lx), 296 (2, M+ -AcOH -NOz), 282 (373, 255 (873, and 145 (100); vmx. (KBr) 1725, 1620, 1 580, and 1 315 cm-'; 6c 176.6 (20-C), 170.4 (0-CO-CH3), 139.7 (5-C), 122.2 (6-C), 73.8 (3-C), 57.7 (17-C), 56.9 (14-C), 49.9 (9-C), 45.1 (13-C), 38.7 (16-C), 38.1 (4-C), 37.0 (1-C), 36.6 (10-C), 32.0 (8-C), 31.6 (7-C), 27.7 (2-C), 24.2 (15-C), 23.5 (12-C), 21.4 (0-CO-CH3), 21.0 (11-C), 19.9 (21-C), 19.3 (19-C), and 13.1 (18-C).17-Nitroimino-5 a-androsfan-3/3-yl Acetate (6).-A solution of 17-oxo-5a-androstan-3P-yl acetate (4) (2.5 g) and hydro- xylamine hydrochloride (1 g) in pyridine (40 ml) was treated as indicated for 20-0xopreg-5-en-3P-yl acetate (l), to yield the oxime (5) (2.4 g) v,,,,,, (CHC13) 3 560 and 1 715 cm-'1 which was used without purification in the next reaction. To a solution of the oxime (2.4 g) in methylene chloride (50 ml) and acetic acid (6 mf), solid sodium nitrite (2.5 g) was added at room temperature for 1 h. Work-up and column chromato- graphy (benzene-n-hexane 75 : 25) yielded the starting ketone (4) (1.5 g) and 17-nitroimino-5a-androstan-3~-ylacetate (6) (0.68 g), m.p.177-178 "C (n-hexane), .ID +5" (c 0.14) (Found: C, 67.2; H, 8.75; N, 7.7. C21H32N204requires C, 67.0; H, 8.6; N, 7.45); m/z 376 (70, M+),360 (15), 345 (lo), 343 (15), 330 (20, M+ -N02), 316 (20, M+ -AcOH), and 270 (loo, M+ -NO2 -AcOH); vmax, (CHCI3) 1 715, 1 640, and 1 560 cm-'. 12-Nitroimino-(25R)-5a-spirostan-3~-ylAcetate (9).-A solution of 12-oxo-(25R)-5a-spirostan-3~-ylacetate (7) (2.5 g) 301 and hydroxylamine hydrochloride (1 g) in pyridine (40ml) was treated as indicated for the preparation of (2), to afford the oxime (8) (2.5 g) vmx. (CHCIS) 3 580 and 1 715 cm-'. The nitro-imine (9) was prepared in quantitative yield from this oxime (8), as previously described for (6).12-Nitroimino-(25R)-Sa-spirostan-3P-yl acetate (9) crystallized from n-hexane, m.p. 197-198 "C, aID +12" (c 0.25) (Found: C, 67.25; H, 8.75; N, 5.45. C29H44N206 requires C, 67.4; H, 8.6; N, 5.4); m/z 470 (50, M+ -NO,), 356 (15), 256 (15), and 139 (100); vmK (CHCI3) 1 720, 1 620, and 1 560 cm-l. 23-Nitroimino-(20S,22S,25S)-5~-spirostan-3~-ylAcetate (12).-Sarsapogenin acetate (lo), biosynthesized by an Agave attenuata Solm. culture 'O with 2-14C, (4R)-4-3H- mevalonic acid (43 mg, 6.88 x lo5d.p.m. mmol-I of 14C)was diluted with carrier material and crystallized to constant specific activity: 1.64 x lo5d.p.m. mmol-' of 14Cand atomic ratio 3H/14C2.0815.To a solution of this material (199 mg) in acetic acid (5 ml) and boron trifluoride-diethyl ether complex (0.2 ml), sodium nitrite (150 mg)was added in small portions with stirring at room temperature during 1.5 h.The mixture was then poured into water, extracted with chloroform and washed with aqueous NaHC03 and water. After drying over Na2S04 the solvent was evaporated and the residue chromatographed (benzene as eluant) to afford 23-0x0-(20S,22S,25S)-5j3-spirostan-3J3-ylacetate (1 1) (30 mg), v,,,, (KBr) 1 740 cm-' and 23-nitroimino-(20S,22S,25S)-5P-spirostan-3P-yl acetate (12) (113 mg), m.p. 173-175 "C (MeOH),a, -74" (c 0.19) (Found: C, 67.3; H, 8.6; N, 5.4. C29H44N206 requires C, 67.4; H, 8.6; N, 5.4); m/z 516 (0.2, M+),470 (33, M+ -NOz), 456 (4, M+ -AcOH), 410 (32, M+ -NO, -AcOH), 389 (3), 344 (22), 329 (3379, 315 (19), 284 (27), and 255 (100); vmx.(CHCl3) 1735, 1 644,1575, and 1 318 cm-'. Sodium Borohydride Reduction of Steroid Nitro-amines: General Procedure.-To a solution of the steroid nitro-imine (1 mmol) in absolute ethanol (50 ml), sodium borohydride (9 mmol) was added and the mixture was stirred at ambient temperature for 1.5 h. After the addition of water the mixture was acidified with aqueous hydrochloric acid (10) and extracted with chloroform. The organic layer was washed with aqueous NaHCO, and water, dried (Na2S04), and evaporated under reduced pressure. acetate (13a). This was (i) 20P-Nitroaminopregn-5-en-3J3-yl purified by column chromatography (benzene-ethyl acetate 9 : 1) to give a 90 yield, m.p.189-190 "C (acetone-n-hexane), aID -56" (c 0.22) (Found: C, 68.35; H, 9.0; N, 6.85. C23H36N204requires C, 68.3; H, 9.0; N, 6.9); m/z 344 (loo, M+ -AcOH), 329 (lox), 298 (30, M+ -AcOH -NO2), 282 (35, M+ -AcOH -NH2N02), and 267 (25); vmax. (CHCI,) 3 370, 3 240, 1 720, and 1 580 cm-'; 6, 171.4 (0-CO-CH3), 139.8 (5-C), 122.3 (6-C), 74.2 (3-C), 55.9 (14-C), 54.4 (20-C), 53.5 (17-C), 50.0 (9-C), 42.2 (13-C), 38.9 (16-C), 38.0 (4-C), 37.1 (1-C), 36.6 (10-C), 31.8 (7-C), 31.8 (8-C), 27.7 (2-C), 26.7 (12-C), 24.1 (15-'C), 21.4 (0-CO-CH3), 20.9 (11-C), 19.2 (19-C), 18.7 (21-C), and 12.4 (1 8-C). Saponification with 2 potassium hydroxide in methanol gave the alcohol (13b), which crystallized from acetone-n-hexane, m.p. 244-246 "C (Found: C, 69.5; H, 9.4; N, 7.6.C21H34N203requires C, 69.6; H, 9.45; N, 7.75); m/z 362 (74, M+), 344 (71, M+ -H20), 316 (21, M+ -NOz), 300 (loo, M+ -NHZNO,), 285 (76),and 267 (99); v,,,. (KBr) 3 380, 3 180, and 1 580 cm-'; 6(2H,pyridine) 5.4 (1 H, m, W, 10 Hz, 6-H), 4.4 (1 H, m, W, 24 Hz, 20-H), 3.7 (1 H, m, W+30 Hz, 3a-H), 1.21 (3 H, d, J7 Hz, 20-Me), 1.02 (3 H, s, 10-Me), and 0.74 (3 H,s, 13-Me). (ii) 17P-Nitroamino-5 u-androstan-3B-yl acetate (1 4a). This was purified by crystallization from ethyl acetate-n-hexane to give a 75 yield, m.p. 158-159 "C, aD =O" (c 0.20) (Found: C, 66.9; H, 9.15; N, 7.3. CZ1HJ4N2O4 requires C, 66.65; H, 9.05; N, 7.4); m/z 332 (8, M+ -NOz), 318 (6, M+ -AcOH), 316 (8, M+ -NHzNOz), 301 (373, 272 (12, M+ -AcOH -NOz), 256 (lo, M+ -AcOH -NHzN02), 241 (2073, and 148 (100); vmx.(CHCI,) 3 390, 1 720, and 1 575 cm-'; 6 4.05 (1 H, m, W, 20 Hz, 17a-H; +DzO: t, J6 Hz). (iii) 12P-Nitroamino-(25R)-5a-spirostan-3~-ylacetate (1 5a) and 12a-nitroamin0-(25R)-5a-spirostan-3~-ylacetate (1 5b). A mixture of the two stereoisomers at C-12 was obtained by reduction of the 12-nitro-imine (9) which was chromato-graphed (benzene-ethyl acetate 97 : 3) to yield (15a) (65) and (15b) (15). The 12P-nitro-amine (I5a) had m.p. 238- 240 "C (n-hexane), aD -42" (c 0.10) (Found: C, 67.0; H, 9.3; N, 5.55. Cz9H46N206 requires C, 67.15; H, 8.95; N, 5.4); M/Z 518 (2, M+),472 (3, M+ -NOz), 456 (5, M+ -NH2N02), 446 (573, 358 (473, and 139 (100); vmX.(CHC13) 3 370, 1710, and 1 570 cm-'. The 12a-nitro- amine (15b) crystallized from n-hexane, m.p. 234-236 "C, aJD-11" (~0.10)(Found: C, 67.4; H, 9.2; N, 5.6. C29H46N206 requires C, 67.15; H, 8.95; N, 5.4); m/z 472 (2, M+ -NOz), 456 (l, M+ -NH2NO2), 446 (lx), 358 (1273, and 139 (100); vmx, (CHCI3) 3 380, 3 220, 1710, and 1575 cm-'. (iv) 23R-Nitroamino-(20S ,22S ,25S)-5 P-spirostan-3 0-y 1 ace-tate (16). This was purified by column chromatography (benzene-ethyl acetate 93 : 7) to give a 95 yield and crystal- lized from methanol to its constant specific activity: 1.63 x lo5 d.p.m. rnrno1-l of 14C and atomic ratio 3H/14C 2.01/5; m.p. 177-179 "C,aID -83" (c 0.34) (Found: C, 66.95; H, 8.9; N, 5.55. C29H46N206requires C, 67.15; H, 8.95; N, 5.4); m/z 472 (15, M+ -NOz), 456 (85, M+ -NHz-NOz), 396 (3, M+ -AcOH -NH2NOz), 255 (5573,and 137 (100); v,,,.(KBr) 3 400, 1 735, and 1 580 cm-'; 6(240 MHz) 4.27 (1 H, m, W, 18 Hz, upon irradiation at 8.41, W* 14 Hz, 23a-H). Denitroamination of Steroid Nitro-amines: General Pro- cedure.-To a solution of the steroid nitro-amine (1 mmol) in pyridine (30 ml), acetic anhydride (6 ml) was added and the mixture was kept at room temperature overnight. After addition of ice-water and solid sodium hydrogen carbonate, the products were extracted with diethyl ether. The organic layer was washed with aqueous hydrochloric acid, aqueous sodium hydrogen carbonate, and water, dried (Na2S04), and evaporated under reduced pressure. (i) Reaction of 20B-nitroarninopreg-5-en-3P-ylacetate (1 3a).The nitro-amine (13a) (1 g) gave a mixture which was chro- matographed on silica gel (benzene-ethyl acetate, 98 : 2) and silica gel containing 20 AgN03 (benzene-n-hexane, 7 : 3) to give pregna-5,20-dien-3P-y1 acetate (1 7) (0.22 g), pregn-Sen- 3P,20P-diyl diacetate (I 8) (0.16 g), 17a-methyl-~-homo-androst-5-en-3,17ap-diyldiacetate (19) (0.22 g), 17u-methyl- 12a-methy/ene-c( 12a)-homo-I 8-norandrost-5-en-3P-yl acetate (20) (0.05 g), and pregna-5,17(20)E-dien-3P-yl acetate (21) (0.012 g). Compound (17) had m.p. 132-1 35 "C (MeOH), aID-82" (c 0.29) (Iit.,l3 m.p. 132.5-135 "C, aID -77"); m/z 282.2336 (52, M+ -AcOH, C21H30, 282.2347), 267.2090 (17, CZ0Hz0, 267.2113), and 213.1638 (16, C16H21, 213.1643); v,,,.(KBr) 3 080 and 1 725 cm-'. Compound (18), crystallized from methanol, had m.p. 130-131 "C, .ID -36" (c 0.20) (lit.,15 m.p. 128.5-131 "C, oilD -34 f4"); m/z 342 (loo, M+ -AcOH) and 282 (15, M+ -2 AcOH); v,,,. (KBr) 1 730 cm-I (Found: C, 74.4; H, 9.6. Calc. for C25H3804: J. CHEM. SOC. PERKIN TRANS. I 1983 C, 74.6; H, 9.5). Compound (19) had m.p. 211-212 "C (MeOH), aJD-117" (c 0.3) (lit.,16 m.p. 210-211 "C, aID-112"); m/z 342 (loo, M+ -AcOH) and 282 (3, M+ -2 AcOH); vmaX.(KBr) 1 730 cm-' (Found: C, 74.7; H, 9.4. Calc. for Cz5H3804: C, 74.6; H, 9.5). Compound (21) crystallized from methanol had m.p. 142-145 "C, aD -68" (c 0.24) (lit.,I4 m.p. 143-143.5 OC,aID-72"); m/z282 (100. M+ -AcOH) (Found: C, 80.75; H, 9.9.Calc. for C23H3402: C, 80.65; H, 10.0). Compound (20) had m.p. 127-130 "C (MeOH), .ID -67" (C 0.27); m/z 282.2330 (M' -AcOH, C21H30 requires 282.2347), 200.1542 (C15HZ0 requires 200.1565), and 8 1.0692 (C6H9 requires 8 1.0704) ; v,,,, (KBr) 3 090 and 1 735 cm-'. (ii) Reaction of 17P-nitroamino-5r.-androstan-3P-y1acetute (14a). Chromatography on siIica gel (benzene) and silica gel containing 20 AgN03 (n-hexane-ethyl acetate 99 : 1) of the crude product of the denitroamination reaction of (14a) (3.1 g) yielded an unresoIved mixture (1.4 g) of 5a-androstan-38,17P-diyl diacetate (25a) and 5a-androstan-3P,1 7a-diyl diacetate (26a) in a ratio 1 : 2 (as estimated by 'H n.m.r.), 5a-androst-1 6-en-3P-yf acetate (27a) (0.41 g), 17P-methyl- 18-nor-5a-androst-12-en-3P-ylacetate (28a) (0.23 g), and a mixture (0.55 g) of 17-methyl-I8-nor-5a-androst-l3(17)-en-3P-yI acetate (29a) and 17~-methyl-l8-nor-5cx-androst-l3-en-3P-yl acetate (30a).The mixture of (25a) and (26a)-or their hydrolysis derivatives-which could not be resolved by t.1.c. or g.l.c., had n.m.r.12 signals at 6 4.80 (d, J 7 Hz, 17P-H), 4.6 (m, 3-H and 17a-H), 0.83 (s, 10-Me), 0.78 s, 13 Me in (25a), and 0.74 s, 13-Me in (26a)l; m/z 316 (62, M+ -AcOH). Compound (27a) crystallized from methanol, m.p. 66-67 "C, oilD -3" (c 0.20); m/z 316 (63, M+),301 (38, M+ -Me), 256 (23, M+ -AcOH), and 241 (loo, M+ -AcOH -Me) (Found: C, 79.5; H, 10.05. CZIH3202 requires C, 79.7; H, 10.2). Saponification of (27a) with 2 potassium hydroxide in methanol yielded the alcohol (27b), m.p.122-123 "C (MeOH), .ID $12" (c 0.24) (lit.,22 m.p. 125-126 "C, aID+ 14"). Compound (28a) was obtained as a gum, m/z 316 (12, M+),256 (llx, M+ -AcOH), and 241 (lo, M+ -AcW -Me). Saponification with 2 potas- sium hydroxide in methanol yielded the alcohol (28b), m.p. 88-89 "C (n-hexane), oilD $3" (c 0.25) (Found: C, 83.25; H, 10.9. C19H300 requires C, 83.15; H, 11.0); m/r 274 (52, M+), 259 (24, M+ -Me), 256 (674, M+ -H,O),241 (26, M+ -H20 -Me), and 148 (100); 6 5.3 (1 H, m, W, 10 Hz, 12-H), 3.6 (1 H, m, W, 30 Hz, 3u-H), 1.00 (3 H, d, J 7 Hz, 17P-Me), and 0.79 (3 H, s, 10-Me). The mixture of tetrasubstituted olefins (29a) and (30a) which could not be resolved, by silica gel or silica gel-20 AgN03 t.1.c.or g.1.c. techniques, had m/r 316 (61, M+) and 256 (13, M+ --AcOH); 6" 1.60 br s, 17-Me in (29a), 0.95 d, J 7 Hz, 17P-Me in (30a), 0.80 s, 10-Me in (30a), and 0.75 s, 10-Me in (29a)l. (iii) Reaction of 12~-nitroamino-(25R)-5a-spirostan-3P-yl acetate (I5a). The nitro-amine (15a) (0.25 g) gave a residue which was chromatographed on a column of silica gel containing 20 AgN03 (benzene-n-hexane 3 : 2) to yield 14( 13 -+ 12aH)abeo-(25R)-5a-spirost-l3(18)-en-3P-yl ace-tate (31) (0.2 g), m.p. 227-228 "C (n-hexane), aID -88" (c 0.12) m.p. 222-224 "C,aID -80.6") (Found: C, 76.3; H, 9.6. Calc. for C29H4404: C, 76.3; H, 9.7); m/z 456 (4, M+),438 (2), 414 (2), 384 (2), 342 (573,165 (3573, 139 (25), and 126 (100); vnlaX,(CS,) 3 080, 1 720, and 1 640 cm-' ; and 14(13 -+ 12)abeo-(25R)-5a-spirost-12-en-3P-yl acetate (32) (0.01 g), m.p.144-146 "C (MeOH), .ID -50" (~0.18)(lit.,23 m.p. 140-142 "C, ID -56") (Found: C, 76.4; H, 9.6. Calc. for C29H4404: C, 76.3; H, 9.7); m/z 456 (9, M+),438 (873, 342 (30), and 126 (100). (iv) Reaction of 23 R-nitroamino-(20S ,22S ,25S)-SP-~pirostan- J. CHEM. SOC. PERKIN TRANS. I 1983 3p-yl acetate (16).The nitro-amine (16) (90 mg) yielded, after purification by column chromatography (benzene-ethyl acetate 95 : 5), (20S,22R,25S)-5fl-spirost-23-en-31)-ylacetate (34)(75 mg) which was recrystallized from methanol to its constant specific activity 1.60 x lo5d.p.m.mmol-' of 14Cand atomic ratio 3H/14C1.9515;m.p. 148-149 "C, aID +7" (c0.13) (lit.," 147-148 "C, aID +6") (Found: C, 75.9; H, 9.75.Calc. for C~gH4404:C, 76.3;H, 9.7); m/z 456 (3, M+),441 (l, M+ -Me), 284 (2), 269 (279, 255 (273, 137 (loo), and 113 (25); vmax.3 025 and 1 735 cm-'; 6 6.12, 6.06, 6.02, and 5.95 (1 H, ABX,24-H). Acknowledgements The authors thank Dr. S. K. Kan (UniversitC Paris XI-Orsay) for the 240 MHz n.m.r. spectrum. This work was supported by the Investigation Programme of the Comisi6n Asesora de Investigacih Cientifica y Tkcnica. References 1 Part 1, C. G. Francisco, D. Melian, J. A. Salazar, and E. Suarez, J. Chem. Soc., Perkin Trans. I, 1982, 923. 2 E. W. White and D. J. 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