The Chromyl Chloride Oxidation of α-Pinene

The oxidation of α-pinene with chromyl chloride has been investigated and 11 compounds amounting to 81% of the total reaction have been isolated and identified. Besides a small amount of recovered α-pinene these compounds have been found to be products of acid-catalyzed rearrangement (bornyl chloride, borneol, and limonene); products of allylic oxidation (myrtenal, myrtenol, and verbenone); and products of oxidative addition-rearrangement (pinocamphone, pinocarveol, campholenaldehyde, and pinol). In addition, p-cymene was isolated which may arise from several oxidation sequences. The isolation of optically active pinol suggests that at least part of the oxidation of α-pinene is initiated by attack of the chromyl chloride on the same side of the double bond as the dimethyl substituted bridge. An attack by a positive chromium atom on the double bond is ruled out by a deuteration study.