Synthesis of conjugated diene pheromones and related compounds

Abstract

Methods for preparing conjugated dienes are described. An α,β-unsaturated E olefin intermediate may be prepared via cross-metathesis using a catalyst comprising a transition metal (e.g., ruthenium), a first carbene ligand (e.g., a substituted indenylidene) and an N-heterocyclic carbene ligand (e.g., an imidazolidinylidene). The catalyst further includes a phenylphosphine ligand, a tri(isopropoxy)phosphine ligand, a dimethylsulfoxide ligand, an acetonitrile ligand, or a pyridine ligand. Following the cross metathesis-step, the α,β-unsaturated aldehyde intermediate may be converted to the conjugated diene product via reaction with a phosphonium ylide. Products obtained via the methods of the disclosure include (7E,9Z)-dodeca-7,9-dien-1-yl acetate, a pheromone produced by(European grapevine moth), and other insect pheromones.