Unusual Reactions of Steroidal and Non-steroidal 1,5-Dioximes. Stereochemistry and Mechanism of Formation of N-Hydroxypiperidine Analogues

4,5-Secocholestane-3,s-dloxlme on NaBHq reduction gave N-hydroxy-38-methyl-4-aza-50-cholestane and N-hydroxy-3a-methyl-4-aza-56-cholestane.The stereochemistry of the products was fully established by converting the N-hydroxy compounds to N-chloro compounds which resulted in 'H nmr signals separating out from the steroid envelope.The dioxime on reaction wlth NH OCH underwent a regiospecific replacement of the oxime at 2 3 C-3 by an oxime ether.In both these reactions thls and other 1.5 dioximes exhibit unique behaviour not shown by isolated oximes.Arguments are presented pin-pointing a single mechanism involving a "oxadiaza" intermediate lsornerlc wlth the dioxime.The conversion of a 1.5-dioxo compound to a N-hydroxypiperidine analogue by treatment with excess NH20H followed by reduction of the resulting product wlth 1 NaBH4 was reported by Gamov et al.I" 1974.They concluded that the products obtained from meso and dl forms of methylene-bis-2.2'-cyclohexanone 1 by reactlon with 2 eq. of NH OH were 8-hydroxy-1,2,4,5-bi~-tetramethylene-7-oxa-6,8-diazabicyclo-2 [3.2.11-octanes -2 .Reduction of 2 wlth NaBH4 in ethanol gave N-hydroxyperhydroacrldines 2.