REACTIONS OF ORTHO-XYLYLENES PRODUCED PHOTOCHEMICALLY FROM ORTHO-ALKYLSTYRENES

The potential synthetic utility of o-xylylenes generated photochemically from o-alkylstyrenes has been investigated. The o-xylylenes produced from 3a, 3b, and 3c were trapped with cyclohexene to yield octahydroanthracene derivatives in good yields (94, 86, and 63%, respectively). In the absence of cyclohexene, the o-xylylene from 3a dimerized to produce 8. Irradiation of 16 gave an o-xylylene which is an enol and which subsequently tautomerized to aldehyde 9. Deuterium-labeling studies supported this mechanism. The quantum yield for formation of 9 upon direct irradiation of 16 was 0.085, and that for the xanthone photosensitized process was 0.027. © 1979, American Chemical Society. All rights reserved.