Enantioselective synthesis of 11-substituted 2- or 3-methoxy-17-vinylgona-1,3,5(10)-trien-13-ols

The acylation of the (±)-spiro-γ-lactone 1 lithium enolate (3 equiv) by the O-TBDMS methyl (−)-(S)-lactate, the O-TBDMS methyl (+)-(S)-mandelate, or the diacetone-d-glucose carbonate (1 equiv each) occurs with a kinetic resolution. The (S,S)-enolate is the most reactive with the lactate and it is the (R,R)-enolate, which selectively reacts with the mandelate or the DAG carbonate. After alkylation of the resulting acyl lactones with 4- or 5-methoxy-1-iodobenzocyclobutene and heating, title compounds were obtained and, after deprotection, the structures of the optically pure new steroids were ascertained by single crystal X-ray analysis.