Beckmann Fragmentation of Camphor-4-carboxylic and Camphor-4-acetic Acid Oximes

A mild and efficient recyclization reaction of bornanone-4-carboxylic and bornanone-4-acetic acid oximes in aqueous hydrochloric acid has been developed. Beckmann fragmentation followed by hydrolysis provides a straightforward method for the preparation and isolation of functionalized [2.2.1] and [3.3.0] bicyclic lactones in nearly quantitative yields. These simple transformations offer the opportunity to obtain a wide range of more complex functionalized bicyclic terpenoids on a large-scale, starting from readily available camphor derivatives.