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Irradiation of 1,3-bis(diazo)indan-2-one (3) in an argon matrix a t 10 K afforded the diazo ketene (7) via the photolabile diazo ketocarbene (5), and further irradiation caused the decomposition of the second diazo group to give strained carbonyl compounds as final photoproducts.

Photochemistry of 1,3-Bis(diazo)indan-2-one: Consecutive Decomposition and Suppression of a Wolff Rearrangement.-Photochemical decomposition processes of the readily obtained title compound (II), the first 1,3-bis(diazo)ketone, in fluid solutions and argon matrices at cryogenic temperatures are studied by characterization of the final products as well as reactive intermediates. A stepwise cleavage of the two diazo groups to give the triplet diazo ketocarbene (IV) as the first-formed transient intermediate, which could be characterized by ESR-and IR-techniques, is revealed. The carbene (IV) reacts with the solvent or trapping agent (cf. (V), (VII), (VIII), (IX)) or undergoes a photochemical Wolff-rearrangement in the absence of trapping agents (cf. (X)). Possible reasons for the suppression of a Wolff-rearrangement in the first stage of the photodecomposition of (II) and detailed mechanistic suggestions are given. -(MURATA, S.; YAMAMOTO, T.; TOMIOKA, H.; J. Am. Chem. Soc. 115 (1993) 10, 4013-4023; Chem. Dep. Mater., Fac. Eng., Mie Univ., Tsu, Mie 514, Japan; EN)