Synthesis of 21-Aryl and Heteroaryl Ethisterones and the Corresponding A-Ring Substituted [2,3-d]lsoxazoles

Steroids: reactions and partial syntheses

“…The removal of the methylene group was attained by selective nitrile oxide addition to the Aro(19) double bond to form two stereoisomeric isoxazolines that were subjected to reductive and hydrolytic cleavage with Mo(CO), in the presence of water. The /3hydroxy ketone intermediate (228) underwent a retroaldol cleavage to give (229), which was converted to a tosylhydrazone, reduced with NaBH,, and deprotected to give (226).17, A multistep synthesis of 22-hydroxy-23,24-dinor-5,7choladien-1,3-diyl diacetate, as a synthon for the preparation of vitamin D analogues, has also been ~e p 0 r t e d . l ~~ Several analogues with a corticoid side chain have been prepared.…”