食用香料(R)-gamma-内酯类的制备

Preparation of (R)-gamma-lactones as flavors

摘要:

本文研究了(R)-gamma-内酯的制备方法。首先高烯丙基醇在脂肪酶CAL-B催化作用下进行拆分，得到(R)-高烯丙基醇和(S)-高烯丙基醇乙酸酯。经过三次拆分后，对映体过量（ee）可达95%以上，两个构型产物的收率在40%左右。(S)-高烯丙基醇乙酸酯经水解和Mitsunobu反应转化为相反构型的产物，收率66%左右。(R)-高烯丙基醇与乙酸酐反应得到(R)-高烯丙基醇乙酸酯，收率91%左右。(R)-高烯丙基醇乙酸酯与硼烷四氢呋喃溶液作用，然后在铬酐的醋酸水溶液作用下氧化，中间产物不经过提纯分离直接进行水解关环，得到(R)-gamma-内酯，收率72%左右。产物ee值在94%以上。

Abstract:

The preparation of (R)-gamma-lactones was studied. The racemic homoallylic alcohols underwent kinetic resolution catalyzed by lipase CAL-B to give (R)-homoallylic alcohols and the corresponding acetates with S configuration. After 3 repeated resolutions, the ee values of the products exceeded 95% and the yields were about 40%. (S)-Acetates of homoallylic alcohols were converted to the opposite configuration in about 66% yield after hydrolysis and Mitsunobu reaction. (R)-Homoallylic alcohols reacted with acetic anhydride to produce the corresponding acetates in about 91% yield. (R)-Acetates of homoallylic alcohols were treated with borane in THF and CrO3 in acetic acid aqueous solution to give the intermediates, which were hydrolyzed and cyclized directly without purification to give (R)-gamma-lactones in about 72% yield with >94% ee.