A Convenient Preparation of 2-Ethyl-4-Carboxycyclohexanone

Abstract

Several years ago in the course of work directed toward the total synthesis of the iboga alkaloids¹, we required relatively large quantities of 2-ethyl-4-carboxycyclonhexanone (1) and its methyl ester as precursors to 3-ethyl-5-carbomethoxycyclohexene. Although it was possible to prepare keto acid 2 from 1,3,5-tricarbomethoxypentane (3) following the published synthesis of 2-methyl-4-carboxycyclohexanone², the overall yield was only 52%. ³ In addition, the isolation and purification of intermediates 4 renders the synthesis rather tedious.