A Facile Synthesis of Optically Pure (−)‐(S)‐Ipsenol Using a Chiral Titanium Complex

A stereocontrolled synthetic route to optically pure (−)-(S)-ipsenol (1), the pheromone of Pityokteines curvidens and various other bark-beetle species is described. Key step of the synthesis is an enantioselective aldol reaction using a chiral titanium–carbohydrate complex (Scheme 1). The carboxylate function of the optically pure β-hydroxy acid 5 thus obtained in mol quantities is then elaborated to the diene moiety by standard methodology (Scheme 2).