(Z)-4,7-Octadiensäure-äthylester und (Z)-Buttersäure-3,5-hexadienylester,zwei neue Aromastoffe der roten Passionsfrucht

Ethyl (Z)-4,7-Octadienoate and (Z)-3,5-Hexadienyl Butyrate, two New Aroma Components of the Purple Passionfruit The isolation of ethyl (Z)-4,7-octadienoate ( 1 ) and (Z)-3,5-hexadienyl butyrate ( 2 ), two new and important aroma constituents of the purple passionfruit (Passiflora edulis SIMS ) is reported. Ester 1 was synthesized by two different routes: (1) via a Wittig reaction between the known 4-oxobutyrate 4 and 3-butenylidenephosphorane, and (2) by thermolysis of (Z)-8-acetoxy-4-octenoate 7 which was readily accessible from (Z,Z)-1,5-cyclooctadiene. Ester 2 was prepared from the known hex-3-yn-5-en-1-ol ( 8 ) by a stereoselective (Z)-reduction of the triple bond to 9 , using Rieke's active metallic zinc, followed by esterification. The organoleptic properties and the taste threshold values of 1 and 2 are given.