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Stereospecificity in the photoisomerization of steroidal α-ketols to lactones

✍ Scribed by Shirley Stiver; Peter Yates

Publisher: Elsevier Science
Year: 1984
Tongue: French
Weight: 178 KB
Volume: 25
Category: Article
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(01)81366-6

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✦ Synopsis

The photoisomerization of 5-hydroxy-6-cholestanones to lactones involves ketene intermediates formed by migration of H-7a; its stereospecificity is independent of hydrogen bonding and is attributed to slowing of rotation about the C-9 -C-10 bond in the alkyl acyl diradicals that are the ketene precursors. Cookson et al 1 --* have reported that ultraviolet irradiation of the epimeric a-ketols 1 and 2 in benzene or ethanol results in their stereospecific isomerization to the lactones 3

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