A Convenient Synthesis of Triacetic Acid Methyl Ester

Abstract

Poly-β-keto compounds play an important role in the biogenesis of natural products such as poly hydroxy phenols and lactones as stated by Birch's “Acetate Hypothesis”^1,2. Poly-β-keto compounds and their derivatives (poly-ketides) have been used as intermediates in the biogenetic type synthesis of these natural products by several workers ^3a,b but they are relatively inaccessible. Triacetic acid lactone I is used mostly despite its low reactivity. This unbranched acetic acid trimer can be prepared from the branched tetramer dehydracetic acid II and oleum⁴.

We have found an easy synthesis for the more reactive polyketide III (triacetic ester) by boiling II in methanol/magnesium methoxide. Alternative approaches to the synthesis of III starting from II⁵, from acetoacetic acid derivatives ^6,7 or acetylacetone⁸ give low yields or are difficult to execute.