Flash decarbonylation

Photo-decarbonylation of the cyclohexanone (32a) is efficient with a quantum yield of 0.9. The reaction yields the two products (33) and (34) in a ratio of 1 2. The cyclopentanone (32b) also decarbonylates photochemically but is less efilcient with a quantum yield of 0.5. A laser flash study has been carried out on these systems and has identified the biradicals produced by the Norrish type I process. The lifetime of the biradicals (35a) and (35b) are O.Ojxs and 0.5 xs respectively. In a related study the photodecarbonylation of cIs- and frans-2,6-diphenylcyclo-hexanone has been shown to yield a mixture of cis- and 2-diphenyl-cyclopentane and cIs- and... 

The cyclopropenone (130) undergoes decarbonylation on flash photolysis in water.The resultant ynamine (131) is accompanied by the enamine (132). The enamine is formed from the carbene (133) and its trapping with water. The ynamine (131) is unstable and transforms into the ketenimine (134). The photo-... 

Flash photolysis experiments on the decarbonylation of Mn(COMe)(CO)s reveal a long-lived transient whose properties are consistent with its stabilisation by an Tj -acyl interaction. Reaction of Mn(CO)5 C(0)Me with [CpFe(CO)2] results in acetyl transfer to give [Mn(CO)5] and CpFe(CO)2Me. Labelling studies show that the acetyl group is transferred intact before CO dissociation leads to the Me product. 2 The acyl complex Mn C(=0)Tol (CO)5 catalyzes SiH/SiD... 

The carbomethoxypivaloylketene 467 was formed as a neat hquid by decarbonylation upon flash vacuum pyrolysis of 2,3-dihydrofuran-2,3-dione 466, and [4 + 2] cycloaddition took place across the C=N bond of the diphenyl-Af-(4-methylphenyl)imine involving reaction of the less hindered but normally less reactive ester carbonyl, giving raise to 468 (Scheme 145) (2001T6757, 1997M381). 

Flash vacuum thermolysis with Ar-matrix isolation or matrix photolysis of 2-phenylbenzo-l,3-dioxan-4-one as well as other precursors gave the ketene 6-carbonylcyclohexa-2,4-dienone 112, as detected by the IR absorption at 2134 cm Flash vacuum thermolysis above 600 °C or matrix photolysis resulted in formation of the fulvenone 114, proposed to arise by decarbonylation of 112 and Wolff rearrangement. The use of C-labeled precursor gave 114 with scrambling revealing the intermediacy of bisketene intermediates 113 in the reaction (Scheme 4.21). 

Tsentalovich, Y. P. and Fischer, H., Solvent effect on the decarbonylation of acyl radicals studied by laser flash photolysis, /. Chem. Soc., Perkin Trans. 2, 729,1994. 

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