Ring closing metathesis directed synthesis of (R)-(-)-Muscone from (+)-Citronellal

A concise and simple synthesis of the valuable perfumery ingredient (R)-(-) -muscone 1 has been achieved through ring closing olefin metathesis (RCM) a ided macrocyclization protocol as the key step. Commercially available star ting material (R)-(+)-citronellal 3 has been employed as a building unit in preparing the acyclic diolefinic substrate 16, which in turn was exposed t o bis(tricyclohexylphosphine)benzylideneruthenium dichloride catalyst 2 to afford the cyclic RCM reaction product 17 in 78% yield. Catalytic hydrogena tion of 17 furnished enantiomerically pure (R)-(-)-muscone 1. (C) 2000 Else vier Science Ltd. All rights reserved.