PREPARATION OF 2'-METHYL-4'-METHYLENESPIRO(ANDROSTADIENE-17,5'(4'H)-OXAZOL)-3-ONE DERIVATIVES FROM PREGN-5-EN-20-YLIDENEACETAMIDE DERIVATIVES BY TREATMENT WITH VILSMEIER REAGENT OR ACID

摘要

A process for preparing oxazoline corticosteroid intermediates of formula (V) wherein R1 represents hydrogene (H), loweralkyl, phenyl or phenylalkyl; R4 represents H or loweralkyl, preferably methyl having either the alpha or beta stereochemistry; and R9 represents hydrogen, fluoro, chloro or loweralkyl. The process comprises contacting a compound of formula (III) herein, with (A) Vilsmeier reagent, followed by acid hydrolysis to yield the compound of formula (V); or alternatively, (B) an acid having a pKa of less than 5, to yield the compound of formula (V).