Synthesis of Methyl 2-oxo-2,3,4,4a,9,10-hexahydrophenanthrene-4a-carboxylates

Abstract

The reaction of methyl 7-methoxy-2-oxotetralin-1-carboxylate (2a) with methyl vinyl ketone in the presence of benzyltrimethylammonium methoxide catalyst yielded the expected tricyclic keto alcohol (3a) and the latter on dehydration with p-toluenesulphonic acid gave the unsaturated ketone (la). This constitutes a general method of synthesis of the title compounds. When sodium methoxide was used as the catalyst in the above reaction, (la) was not obtained.