Stereo- and Regioselectivity in Dynamic Gas-Phase Thermoisomerization (DGPTI): Novel Route to α-Campholanic Acid and Derivatives

Dynamic gas-phase thermoisomerization (DGPTI) of (−)-2-phenylisoborneols effects stereo- and regioselective ring opening under formation of (+)-trans-α-campholanic acid derivatives. Similarly, (−)-α-2-phenylfenchol underwent under DGPTI conditions ring opening to (−)-fencholic acid derivatives. In both cases, DGPTI led to cleavage of the weakest bond in the isomeric bicyclic structures. A reaction mechanism involving a diradical intermediate is supported by a deuterium labeling study.