Titanium Tetrachloride Promoted Knoevenagel Condensation of a Sterically Hindered Keto Ester. A High Yield Synthesis of Camphoronic Acid

Abstract

Camphoronic acid (I), a compound with a relatively simple NMR spectrum, not complicated by any spin-spin couplings of the vicinal proton type, is a very good model for investigating the cyclization preferences in the asymmetrically substituted 1,2,3-propanetricarboxylic acids carrying no other functional groups. Its total synthesis, yielding the racemic product, has been already accomplished in two different ways, either using ethyl 2,2-dimethylacetoacetate as the starting material^1,2.