Sunlight oxidation of alkyl aryl tellurides to the corresponding carbonyl compounds: a new carbonyl precursor.

Alkyl aryl tellurides were efficiently transformed to the corresponding carbonyl compounds by photo-oxidation with sunlight without affecting various functional groups in the alkyl moiety. The tellurides can be used as a new carbonyl precursor, and the photolysis can be conducted without special equipment for light sources.

Facile photochemical transformation of alkyl aryl selenides to the corresponding carbonyl compounds by molecular oxygen: use of selenides as masked carbonyl groups.

Alkyl aryl selenides with and without functional groups on the alkyl group were transformed efficiently into the corresponding carbonyl compounds, particularly primary alkyl aryl selenides in good yields, by a simple photolysis in the presence of air or oxygen. This transformation can be conducted without protection of functional groups. The yield of carbonyl compounds was much affected by the solvent viscosity, reaction temperature, concentration of dissolved oxygen in the solvents, wavelength of light, and structure of the aryl substituents.

Factors controlling photochemical cleavage of the energetically unfavorable Ph-Se bond of alkyl phenyl selenides.

Primary photochemical paths of alkyl phenyl selenides (1) were investigated, and an origin of large deviations in the chemical yields of products obtained by carbon radical reactions induced by photolysis of phenyl selenides was clarified. KrF excimer laser photolyses of n-pentyl phenyl selenide (1a) yielded 1-pentene (2a), n-pentane (3a), n-decane (4a), dipentyl selenide (5a), benzene (6), dipentyl diselenide (7a), and diphenyl diselenide (7) as major photoproducts, with compounds 2a, 3a, 4a, 5a, and 7 formed by pentyl-Se bond cleavage, and 5a, 6, and 7a by Ph-Se bond cleavage. The selectivity of the photoproducts revealed the occurrence of an unexpected amount of Ph-Se bond cleavage (35% in n-hexane at 248 nm) during photolysis.