Stereoselective Enzymatic Synthesis of cis-Pelk'torine,a Taste Active Alkamide Naturally Occurring in Tarragon

摘要

The alkamide cis-pellitorine[(2E,4Z)-N-isobutyldeca-2,4-di-enamide]that occurs naturally in tarragon was prepared in yields up to 80% by lipase-catalyzed conversion of ethyl 2￡,4Z-decadienoate,the so-called pear ester,and isobutyla-mine both with and without the use of cosolvents.Of 13 different commercial enzyme preparations tested(lipases,proteases,esterases),only the lipase type B from Candida an-tarctica has a suitable activity.The reaction of the different geometric isomers of ethyl 2,4-decadienoate to the appropriate pellitorines shows a remarkable selectivity:the 2E,4Z ester is converted between 1.4 and 3.9 times faster than the 2￡,4￡ isomer,and the relative yield of cis-pellitorine compared with trans-pellitorine is 5.7 to 16.3 times higher.In contrast to the better known trans-pellitorine,which at 10ppm is only slightly tingling and numbing,cj's-pellitorine shows very interesting pungent and warming sensations after tasting trials already in low concentrations of 10 ppm.