Studies on the identification and synthesis of insect pheromone: XVI. Synthesis of the optically active sex pheromone of gypsy moth and its three other optical isomers

Abstract

The title compounds 1a～d were synthesized from(+)-(R)-glyceraldehyde acetonide (2) obtained from mannitol in 9～10 steps in an overall yield of 20～30%. Thus, Grignard reaction of 2 with n-C_(10)H_(21)MgBr yielded a mixture of two diastereoisomers which afforded 3(erythro form, R, S) and 4 (threo form, R, R) by SiO_2 gel chromatography. The free alcohol 3 was reacted with benzyl chloride followed by acidic hydrolysis to give diol 6 which on selective tosylation followed by treatment with 0.25 M methanolic KOH gave an epoxide 8. 8 was treated with(i-hex)_2 OuLi in ether to give 9 which on removal of the benzyl protecting group followed by reaction with HBr-HOAc gave a mixture of 11a and 11b. Finally, treatment of the mixture of 11a and 11b with 0.5M methanolic KOH gave (+)-disparlure(1a). 1c and 1d were obtained from 9 by the reaction sequences as shown in the Chinese Text. The (-)-disparlure (1b) was obtained from 4 by the reaction sequences of 5'→6'→7'→8'→9'→1b.