General Methods for the Synthesis of Macrolactones

Yonemitsu et al. [46] modified the Yamaguchi conditions in which the mixed anhydride is not isolated and DMAP is directly introduced at room temperature from the beginning. Shiina et al. [47] described the use of 2-methyl-6-nitrobenzoic anhydride (MNBA) as an alternative to 2,4,6-trichlorobenzoyl chloride. Pivaloyl chloride [48], trifluoroacetic anhydride [49], AC2O [50], and B0C2O [51] are also employed for the lactonization via mixed anhydride under basic conditions. Furthermore, Yamamoto et al. [52] described the use of Sc(OTf)3 as a Lewis acid. 

In 1981, Mitsunobu [60] described the extension of their method of ester preparation for the synthesis of macrolactones using a mixture of Ph3 P and diethyl azodicarboxylate (DEAD) as dehydrating agent. 

In 1984, Gatfield [68] observed that a lipase Mucor miehei) is able to catalyze the intramolecular esterification of 15-hydroxypentadecanoic acid to pentadecanolide 

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