Steroidal N-nitroamines. Part 3. Pyrolytic denitroamination of N-nitroamino-adamantane and -bornane, and of several steroidal N-nitroamines

Abstract

The thermal decomposition of several nitroamines has been investigated. The axial nitroamines 6β-nitro-amino-5α-cholestan-3β-yl acetate (1) and 23R-nitroamino-(20S,22S,25S)-5β-spirostan-3β-yl acetate (8) gave exclusively nitrogen-free olefins. The trans-diaxial α-hydroxy nitroamines (2) and (3) afforded the 5α- and 4α-oxirane (6) and (7), and small amounts of the corresponding trans-diols (4) and (5). The 7β- and 7α-nitroaminocholest-5-en-3β-yl acetate (10) and (11) gave 7-oxocholesteryl acetate (14) and a mixture of the 7β- and 7α-alcohol (12) and (13) with 50 and 33% inversion of configuration, respectively. The oxidation product adamantanone (16) was produced together with adamantan-2-ol (20) in the pyrolysis of 2-nitroaminoadamantane (19). Carbon–carbon rearrangement was observed in the case of exo-2-nitroaminobornane (22) and 20β-nitroaminopregn-5-en-3β-yl acetate (25). The nitroamine (25) yielded the 3-o-acetyl derivatives of pregna-5,20-dien-3β-ol, (29), pregna-5,17(20)(E)-dien-3β-ol, (30), 3β-hydroxypregn-5-en-20-one, (28), 17α-methyl-D-homoandrost-5-ene-3β,17aβ-diol, (31), and a mixture of pregn-5-ene-3β,20-diols (26) and (27). Camphene (23) and tricyclene (24) was obtained from exo-2-nitroaminobornane (22). Mechanisms for the formation of these products are discussed.