Electrochemical Oxidation of Polycyclic Cyclopropanes and Camphene. Novel Synthesis of exo-5,5-Dimethyl-6-methylenebicycloheptan-2-ol (Nojigiku Alcohol)

Article abstract of DOI:10.1021/jo00296a069

Anodic oxidation of tricyclene (1a) in acetic acid containing triethylamine, followed by hydrolysis, provides a facile and efficient synthesis of exo-5,5-dimethyl-6-methylenebicyclo<2.2.1>heptan-2-ol (2a), named "nojigiku alcohol", which was isolated from the essential oil of chrysanthemum japonese.Furthermore, a method for large-scale production of 2a starting from the readily available impure starting tricyclene (1a) has been developed by appropriate selection of reaction conditions.Similar electrooxidation of the related naturally occurring polycyclic methylcyclopropanes, cyclofenchene (1b) and longicyclene (1c), followed by hydrolysis also brought about stereo- and regioselective cleavage of carbon-carbon bonds of the cyclopropane rings to give the corresponding homoallylic alcohols 2b,c in good yields.