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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.Thermal and photochemical reactions of sodium salts of P-phosphono tosylhydrazones have been investigated. When the sodium salt of dimethyl a-acetylmethylphosphonate tosylhydrazone is heated, the dimethoxyphosphonyl anior , though a relatively strong base, was eliminated. On the other hand, ultraviolet irradiation of the sodium salts of P-phosphono tosylhydrazones leads to dimethoxyphosphonyl-substituted olefins, presumably via the carbene intermediate. Some of the products result from a previously unreported phosphonyl group migration to a carbene.The migration of phosphonyl groups t o electron-deficient centers has been intensively investigated for carbonium o x y g e r~,~ a n d n i t r~g e n .~ In t h e migration

Die Photolyse der o‐Alkylstyrole (I) liefert die isomeren 1,2‐Dimethylen‐cyclohexadiene ( II), die z.B. zu (III) dimerisieren oder in Gegenwart von Cyclohexen (VI) zu den Dien‐ Addukten (VII) führen.