177. The Enantioselective Synthesis of (+)-Estradiol from 1,3-Dihydrobenzothiophene-2,2-dioxide by Successive Thermal SO2-Extrusion and Cycloaddition Reactions

Article abstract of DOI:10.1002/hlca.19800630638

The optically pure steroid (+)-15 has been synthesized from the easily accessible (+)-carboxylic acid 11 by a sequence of 7 steps in 50percent overall yield.The key steps are the regioselective deprotonation/alkylation 7+13->14 and the thermal SO2-extrusion/cycloaddition 14->15 (Scheme 3).The compound (+)-15 has been readily converted to the naturally occurring (+)-estradiol (17) in 60percent yield.