Highly Selective Conversion of Spiculisporic Acid to Ester, Amide and Imide Derivatives

Abstract

Spiculisporic acid (1), produced by Penicillium spiculisporum, is well known as a member of microbial biosurfactants. (1) is a polyfunctional compound having a five-membered lactone and two carboxylic groups. However, relatively little work has been reported on the preparation of its derivatives. (1) readily reacted with diazomethane to give an optically active ester (2) in 93% yield and was also converted to 3-decyl-4- (2-carboxyethyl) maleic anhydride (4) in 87% yield by heating it under reduced pressure. We describe here the preparation of other derivatives from (2) and (4). (4) reacted with various alcohols by refluxing in benzene in the presence of p-TsOH as an acid catalyst to give terminal esters (5) in high yields. Conversion to the terminal ethyl ester of (4) in 95% yield was easily achieved by treating (6), prepared from (4) and 1, 3-thiazolidine-2-thione, in ethyl alcohol at room temperature in the presence of K2CO3 as a base catalyst. The lactone ring of (2) reacted with dodecylamine under high pressure (8, 000kg/cm2) at 60°C to give an optically active hydroxy amide (7) in 86% yield. Reactions of (4) via the acyl chloride with amines afforded terminal amides (8) in low yields, together with triamides (9) and amide-imides (10). (8) were also obtained in high yields by only mixing (6) with amines in CH2Cl2. Imides (11) were prepared in good yields by refluxing a benzene solution of (4) and equimolar amounts of amines. When (4) was refluxed in toluene with two equimolar amounts of amines, (10) and (11) were obtained in a 1 : 1 molar ratio.