AUTOXIDATION STUDY OF CAROTANE SESQUITERPENES POSSESSING A NONCONJUGATED 1,4-DIENE SYSTEM

The autoxidation process of carota-1,4-diene derivatives was studied. Several intermediate compounds ln the autoxidation were isolated and c haracterized by spectroscopic methods, and two pathways, yielding 1,5- epidioxy-2-hydroperoxy derivatives and 1,5-epidioxy-14-norcarot-2-en-4 -one, respectively, were confirmed. 5-Hydroperoxy-1,3-dienes undergoin g spontaneous cyclization to yield 1,5-epidioxy derivatives were isola ted as key intermediates in the first oxygen-addition step, whereas 1, 5-epidioxy-4-hydroperoxy derivatives were identified as precursors of 1,5-epidioxy-14-norcarot-2-en-4-one. These observations supported a un ique radical-mediated peroxidation process for carota-1,4-dienes.