Chiang, Yvonne; Kresge, A. Jerry; Pruszynski, Przemyslaw, Angewandte Chemie, 1991, vol. 103, # 10, p. 1391 - 1392
作者:Chiang, Yvonne、Kresge, A. Jerry、Pruszynski, Przemyslaw、Schepp, Norman P.、Wirz, Jakob
DOI:——
日期:——
Photochemistry of matrix-isolated (.alpha.-diazobenzyl)phosphonate. Observation and reactions of phosphonylphenylcarbene, phosphonyl phenyl ketone oxide, and phenylphosphonyldioxirane
Photolysis of dimethyl alpha-diazobenzylphosphonate (1) in an Ar matrix at 10 K resulted in the appearance of new absorption bands at 1268, 788, and 536 cm-1, attributable to the carbene 2. The assignment was based on the observation that the new absorptions disappeared upon thawing of the CO-containing matrix to produce the ketene 3, which can be generated by photolysis of (alpha-diazophenacyl)phosphonate 4. Photolysis of 1 in an Ar matrix doped with 20% O2 at 10 K produced benzoylphosphonate 5 along with benzoyl phosphate 8. Generation of 2 in a 0.3% O2-containing matrix, followed by warming of the matrix to 35 K in the dark, resulted in the total disappearance of the band arising from 2 and the concurrent appearance of a new intermediate, identified as the carbonyl oxide 6. Photolysis of 6 with visible light (lambda > 480 nm) gave the corresponding dioxirane 7, which was converted to the ester 8 by further irradiation (lambda > 350 nm); none of the phosphate 9, expected to arise via phenyl migration in the photoisomerization of 7, was detected.
Computational and Experimental Studies of the Effect of Substituents on the Singlet−Triplet Energy Gap in Phenyl(carbomethoxy)carbene
作者:C. Michael Geise、Yuhong Wang、Olena Mykhaylova、Brian T. Frink、John P. Toscano、Christopher M. Hadad
DOI:10.1021/jo0255330
日期:2002.5.1
The effect of aromatic substitution on the singlet-triplet energy gap in substituted phenyl(carbomethoxy)carbene (X-Ph-C-CO(2)CH(3), PCC) has been explored by time-resolved infrared (TRIR) spectroscopy and gas-phase computational methods. The ground state of para-substituted PCC is calculated to change from the triplet state in p-NO(2)-PCC (Delta G(ST) = 6.1 kcal/mol) to the singlet state in p-NH(2)-PCC
Generation of the Enol of Methyl Mandelate by Flash Photolysis of Methyl Phenyldiazoacetate in Aqueous Solution and Study of Rates of Ketonization of This Enol in That Medium
作者:Y. Chiang、A. J. Kresge、N. P. Schepp、R.-Q. Xie
DOI:10.1021/jo991707a
日期:2000.2.1
Flash photolysis of methyl phenyldiazoacetate in aqueous solution produced phenylcarbomethoxycarbene, whose hydration generated a short-lived transient species that was identified as the enol isomer of methyl mandelate. This assignment is supported by the shape of the rate profile for decay of the enol transient, through ketonization to its carbonyl isomer, as well as by solvent isotope effects and