Synthesis of the Four Stereoisomers of 6-Acetoxy-19-methylnonacosane, the Most Potent Component of the Female Sex Pheromone of the New World Screwworm Fly, with Special Emphasis on Partial Racemization in the Course of Catalytic Hydrogenation

Authors

Kenji Mori, Fuji Flavor Co., Ltd., Tokya, Japan
Takashi Ohtaki, Tohoku University, Tsutsumidori-Amamiya 1-1, Aoba-ku, Sendai, Miyagi 981-8555, Japan
Hiroshi Ohrui, Tohoku University, Tsutsumidori-Amamiya 1-1, Aoba-ku, Sendai, Miyagi 981-8555, Japan
Dennis Berkebile, USDA-ARSFollow
David A. Carlson, USDA-ARS

Document Type

Article

Date of this Version

February 2004

Comments

Published in Eur. J. Org. Chem. 2004, 1089-1096.

Abstract

Starting from the enantiomers of citronellal and 1-octyn-3- ol, all four stereoisomers of 6-acetoxy-19-methylnonacosane were synthesized with sufficiently high stereochemical purities (more than 90% ee at C-6; about 97% ee at C-19) for their biological testing as the female sex pheromone of the screwworm fly (Cochliomyia hominivorax). All four isomers showed strong pheromone activity even at 1 μg, and no significant difference was observed in their potency. Adams’ platinum oxide was found to cause partial racemization of enantiomerically pure secondary propargylic alcohols in the course of their catalytic hydrogenation to saturated and secondary alcohols, while palladium-charcoal was less potent in causing partial racemization. A new HPLC-based discrimination of chiral and secondary alcohols proved to be useful in following such a subtle partial racemization.