Rearrangement approaches to cyclic skeletons. IX. Stereoselective total synthesis of (±)-camphorenone based on a ring-contraction of bicyclo[3.2.1]oct-6-en-2-one. Reliable one-step diazo transfer followed by a Wolff rearrangement

Article abstract of DOI:10.1246/bcsj.68.2687

A direct diazo transfer reaction to bicyclo[3.2.1]oct-6-en-2-ones and related compounds was accomplished by treatments with 2,4,6-triisopropylbenzenesulfonyl azide and potassium t-butoxide at -78°C in THF. A Wolff rearrangement of the resulting α-diazoketones in the presence of water gave ring-contraction products, bicyclo[2.2.1]heptenecarboxylic acids. Using these two transformations the total synthesis of (±)-camphorenone was achieved stereoselectively, starting from 1-methoxybicyclo[2.2.2]oct-5-en-2-one.