ISSN:
1420-9071
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The intramolecular substitution of the angular methyl groups in steroids by attack of O-radicals derived from 6β-, 11β, and 20-alcohols is discussed. Irrespective of their genesis, these radicals abstract a hydrogen atom from one of the said methyl groups, suitably oriented inδ-position. The C-radicals thus formed give different products depending on the neighbouring groups. It is shown that 20-hydroxy-18-C-radicals combine with iodine atoms, to give 18-iodides which can befurther substituted through radicals to give potential 18-oxo-compounds in high yield. In the case of 20-cyanohydrines, the intramolecular reaction of the 18-C-radical with the cyano groups gives rise to the new 18-cyano-20-oxo-steroids. With 6β- and 11β-O-radicalssingle substitution in 19-position predominates, since the steric arrangement of the primary product favours the intramolecular ether formation over a second substitution reaction. A general reaction scheme for these transformations is proposed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02158305
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