Straightforward Synthesis of (R)‐(−)‐Kjellmanianone

Abstract
A direct route to enantiomerically pure (−)-kjellmanianone is reported. The synthesis involves a cerium-catalyzed α-hydroxylation and an enzyme-catalyzed procedure to resolve tertiary alcohols at key stages. The intermediate β-oxo ester was α-hydroxylated to give good yields of racemic kjellmanianone. The resolution of the racemic material was achieved by enzymatic saponification, followed by a chemical decarboxylation sequence to give enantiopure (−)-kjellmanianone with 99 % ee. Bromination then afforded the (−)-bromo derivative, whose X-ray structure provided evidence for the R configuration of (−)-kjellmanianone.