REARRANGEMENT APPROACHES TO CYCLIC SKELETONS .9. 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

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 degrees C in THF. A Wolff rearrangement of the resulting alpha-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.