Decarboxylation of Bridgehead Carboxylic Acids by the Barton Procedure

Reductive decarboxylation of a series of bicyclic and polycyclic acids in which the carboxyl group is attached to the bridgehead position has been investigated. Conversion of the acids into thiohydroxamic esters occurs via reaction of the derived acid chlorides with N- hydroxypyridine-2-thione. Decomposition of the esters proceeds smoothly in boiling benzene in the presence of t-butyl mercaptan to give the reduced product in high yield. The procedure appears to be generally applicable, and is unaffected by functional groups such as esters and acetals.