A-Norsteroids

摘要

Method is provided for cyclization of polyunsaturated substituted acylic or monocarbocyclic initiator group containing compound having an endocyclic double bond with a chalcogen atom in the allylic position of the initiator group and having at least two sites of unconjugated aliphatic unsaturation in the side chain substituent on the ring. The polyunsaturated compound is cyclized in the presence of a strong acid in a protic solvent which is inert to the acid, preferably a hydroxylic solvent. Mild temperatures and varying times are employed. The products are useful primarily as intermediates for naturally occurring and synthetic steroids. By appropriate substitution of the side chain, the steroidial products are provided with the substituent at C-11, which upon cyclization results in the alpha-configuration. By resolution of the intermediates prior to cyclization, optically active steroids can be obtained.