Primary, secondary and tertiary alcohols, which are sensitive under basic or acidic reaction conditions, can be O-benzylated under mild acidic reaction conditions using benzyl 2,2,2-trichloroacetimidate as the benzylation agent. Chiral substrates, which have a tendency towards racemization under basic reaction conditions, can be benzylated without any loss of chirality.
Synthesis of (3<i>S</i>)-Hydroxyandrosta-5,7-diene-17-ones via Intramolecular Cobalt-Mediated [2+2+2] Cycloaddition
作者:Ulrich Groth、Norbert Richter、Aris Kalogerakis
DOI:10.1055/s-2006-939064
日期:——
A new method for the synthesis of lumisterin-type steroids following the D→ABCD approach is reported. A key step is the cobalt-induced cyclization of a cyclopentanoid enediyne, which was prepared via thioalkylation of the zinc enolate of a 2,3-substituted cyclopentanone with α-chlorosulfides.