5a-Pregnan-20-one

During synthesis of the hormone rf-aldosterone, 20,21-dihydroxy-lip,18-epoxy-5a-pregnan-3-one diacetate was oxidised to the 3-oxo acid by stoich. RuOy CCl [78, 79], Oxidation of a substituted pyrrolidine to a pyroglutamate, part of the total synthesis of the antibiotic biphenomycin B, was effected by RuO /aq. Na(lO )/ EtOAc [102], Oxidation of a number of A-5 steroids to enones was effected by RuClj/TBHP/cyclohexane [391] safety aspects of these large-scale reactions were examined, as in the preparation of the antibacterial squalamine [186],... 

Funtumafrine-B (XXX) and funtumafrine-C (XXXI) were obtained from the leaves of Funtumia africana via the soluble oxalates. The IR-spectrum of both alkaloids disclosed the presence of a carbonyl group (1706 cm i) and their structure was established by the preparation from funtuphyllamine-B (furnishing funtumafrine-B) and funtuphyllamine-C (furnishing funtumafrine-C) on chromic acid oxidation 17, 18). 20a-Dimethylamino-5a-pregnan-3-one had been previously reported as a product of partial synthesis 20). 

Starting material for the synthesis of 5a-conanine (II) was 20a-methylamino-5a-pregnan-3-one (CLXIII) which had been prepared in several steps from 3)3-acetoxy-5a-pregnan-20-one via the corresponding oxime. 

The presence of one methylamino and one dimethylamino group in this alkaloid (CCCLXXIII) is disclosed by its NMR-spectrum which also reveals two tertiary C-methyl groups. On methylation, pachysamine-A furnishes 3a,20 -bisdimethylamino-5a-pregnane Ruschig degradation to 20a-dimethylamino-5a-pregnan-3-one (funtumafrine-C, XXXI) proves the location of the secondary amine function in position 3 225). 

The oxidation of steroidal 3a-, 3)5-, 20a-, and 20j8-amines with m-chloroper-benzoic acid to the corresponding nitro-compounds has been described. Oxidation of several steroidal tertiary amines with chromic acid in pyridine leads to the corresponding N-formyl derivatives. Photosensitised irradiation (methylene blue) of 20a- and 3)5-dimethylamino-steroids leads to a secondary amine in 80% yield. The formyl derivative (10% yield) is not an intermediate in the N-demethylation reaction. 3a-Dimethylamino-5a-pregnane gives 5a-pregnan-3-one and the secondary amine. Conanine gives the lactam (50). ... 

Alkaloid C from Sarcococca pruniformis has been identified as 3a-methoxy-20a-dimethylaminopregn-5-ene (43). Emde degradation of (43) followed by catalytic hydrogenation afforded 3a-methoxy-5a-pregnane (44), identical with a sample prepared from 5a-pregnan-3-one.34... 

S)-3/3-Dimethylamino-18,20-diacetoxy-5a-pregnane (1) was prepared from 20/3-hydroxy-5a-pregnan-3-one cyclic ethylene ketal (2) in six steps. The key steps were iodination of (2) with HOI and cyclization to ether (3). ... 

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