Thermolysis and Photosensitized Oxygenation of Tetrasubstituted Cyclopropenes
作者:Aryeh A. Frimer、Michal Afri、Simeon D. Baumel、Pessia Gilinsky-Sharon、Zilpa Rosenthal、Hugo E. Gottlieb
DOI:10.1021/jo991803b
日期:2000.3.1
enones are the oxygenation products. The oxygenation was slowed by radical inhibitors, but not by (1)O(2) quenchers; nor were any oxidation products observed when these cyclopropenes were reacted with triphenylphosphine ozonide, a chemical (1)O(2) source. The data indicates that a photosensitizer-initiated free radical autoxidative process is involved. Likely intermediates in this oxygenation are epoxide
substrates having a bulky substituent, such as a tert-Bu group, at the beta-position give high yields. Bulkiness is also required in cyclic alpha,beta-unsaturated ketones, but the effect is small. In alkyl vinyl ketones, the reactivity decreased with the steric bulk of the alkyl group. In aryl vinyl ketones, the presence of an electron-donating group on the aromatic ring decreases the reactivity. The