Steroids monohydroxylated

Hydroxyl group effects were determined by Djerassi and co-workers (110) (cf. Sect. HI) by analysis of 31 monohydroxylated steroids. The following relationships were given ... 

The 13C NMR spectra of monohydroxylated steroids demonstrate that the y-gauche substituent effects (the hydroxy group and the y-carbon are gauche to each other) are different for secondary (average value — 6.5 ppm) and tertiary (average value — 7.8 ppm) y-carbons. For the y-trans shifts much smaller values in the range of + 1.3 to — 3.0 ppm are found [575],... 

Substitution on the steroid nucleus by fluorine leads to complicated changes in selectivity, but usually results in hydroxylation at sites remote from the fluorine substituent. Thus Sa-androstan-17-one (77) is primarily 7, 1 la-dihydroxylated by Aspergillus ochraceus, but the 12,12-difluoro derivative (78) is 7p-monohydroxylated (Scheme 14). ... 

Osawa, Y., N. Yoshida, M. Fronckowiak, and J. Kitawaki (1987). Immunoaffinity purification of aromatase cytochrome P-450 from human placental microsomes, metabolic switching from aromatization at ip and 2p-monohydroxylation, and recognition of aromatase isozymes. Steroids 50, 11-28. 

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