(+)-(R,Z)-5-Muscenone and (−)-(R)-Muscone by Enantioselective Aldol Reaction and Grob Fragmentation

(+)-(R,Z)-5-Muscenone ((R)-1) was synthesized by an enantioselective aldol reaction, catalyzed by new ephedrine-type Ti reagents (up to 70 % enantiomeric excess). Substrate-directed diastereoselective reduction of the aldol product and Grob fragmentation of the tosylate of the resultant 1,3-diol afforded (+)-1. This approach also gave access to (−)-(R,E)-5-muscenone and (−)-(R)-muscone.