Mass Spectrometry in Structural and Stereochemical Problems. CCXVII. Electron Impact Promoted Fragmentation of <i>O</i>-Methyl Oximes of some α,β-Unsaturated Ketones and Methyl Substituted Cyclohexanones
作者:Younus M. Sheikh、Raymond J. Liedtke、A. M. Duffield、Carl Djerassi
DOI:10.1139/v72-444
日期:1972.9.1
delineate the modes of mass spectrometric fragmentation of O-methyl oximes of α,β-unsaturated ketones and methyl substituted cyclohexanones. α,β-Unsaturated ketone and 2- and 4-methylcyclohexanone O-methyl oxime ether derivatives fragment upon electron impact in a manner reminiscent of the carbonyl derivatives from which they were prepared. However, several fragmentation sequences characteristic of the O-methyl
Rh(III)-Catalyzed Addition of Alkenyl C–H Bond to Isocyanates and Intramolecular Cyclization: Direct Synthesis 5-Ylidenepyrrol-2(5<i>H</i>)-ones
作者:Wei Hou、Bing Zhou、Yaxi Yang、Huijin Feng、Yuanchao Li
DOI:10.1021/ol4003674
日期:2013.4.19
The rhodium-catalyzed addition of an alkenyl C–H bond to isocyanates via sp2 C–H bond activation followed by an intramolecular cyclization is described. This atom-economic and catalytic reaction affords a simple and straightforward access to biologically relevant 5-ylidene pyrrol-2(5H)-ones and can be carried out under mild and neutral conditions in the absence of any additives and environmentally