Improved Synthesis of Optically Active Ipsdienol

Abstract

In our preceding publication a simple procedure was described for the preparation of both enantiomers of monoterpene alcohol ipsdienol 1, an actual pheromone component of bark beetle of genus Ips. The key synthesis stage was the resolution of the direct precursor of the ipsdienol, (±)-6-methyl-2-(2- chloroethyl)hepta-1,5-dien-4-ol by its conversion into acid phthalate and the crystallization of the acid phthalate as salt with (+)- or (–)-1-phenylethylamine. Then the optically active acid phthalates (S)-2 and (R)- 2 were treated with potassium tert-butylate in tertbutyl alcohol. By the dehydrochlorination and the simultaneous alcoholysis of the ester moiety in one stage (S)- or (R)-ipsdienol was obtained in a 55% yield.