Carbon Atom Insertion into Pyrroles and Indoles Promoted by Chlorodiazirines
作者:Balu D. Dherange、Patrick Q. Kelly、Jordan P. Liles、Matthew S. Sigman、Mark D. Levin
DOI:10.1021/jacs.1c06287
日期:2021.8.4
calculations supporting a selectivity-determining cyclopropanation step. Computations surprisingly indicate that the stereochemistry of cyclopropanation is of little consequence to the subsequent electrocyclicringopening that forges the pyridine core, due to a compensatory homoaromatic stabilization that counterbalances orbital-controlled torquoselectivity effects. The utility of this skeletal transform is
p-Substituted 1-chloro-3-phenyldiazirines (5), the putative intermediates of the reaction of N,N,N'-trichlorobenzamidines (10) with excess of bromide ions, react further to afford mixtures of 3-bromo- (4) and 3-chloro-3-phenyldiazirines (6). The 6:4 ratios inversely correlate with the Hammett σp and σp+ constants of the p-substituents. The formation of 4, proposed to proceed by anti-SN2‘ mechanism
对位取代的1-氯-3-苯基重氮(5)是N,N,N'-三氯苯甲m(10)与过量溴离子反应的推定中间体,进一步反应生成3-溴-(4)和3-氯-3-苯基重氮(6)。该6:4的比率用哈米特σ负相关p和σ p +的常数p -取代基。4的形成,建议通过反S N进行2'机理主要是吸电子的p-取代基。化合物6是具有给电子性p取代基的主要产物,它可以由5通过极性过渡结构12进行氯的[1,3]-σ位移而从5中产生。气相DFT(B3LYP / 6-31 + G *)对这两种机理的研究结果与实验一致。
Photolysis of 3-chloro-3-aryldiazirines in the presence of amines and allyl alcohol
作者:Michael T. H. Liu、Yuri N. Romashin、T. K. Venkatachalam
DOI:10.1139/v94-250
日期:1994.9.1
presence of phenylallylamine produces a rearranged product in poor yield (11–15%) whereas the reaction of allyl alcohol with arylchlorocarbene gives exclusively diallyl acetals in high yield (70%). The rate constants for these reactions were obtained by laser flash photolysis. Allylphenylether forms a cyclopropanated product when treated with arylchlorocarbene. The different behaviour of these compounds
reactions of phenylchlorocarbene and related carbenes with alkenes are summarized and systematized. The experiments described provide the basis for a detailed examination of carbenic reactivity-selectivity principles. The results of studies on the influence of temperature on the absolute rate constants for carbene reactions are consistent with the existence of transient carbene/alkene intermediates.
Sulfur ylides generated from the reaction of arylchlorocarbenes with trimethylenesulfide: determination of rate parameters by laser flash photolysis
作者:Yuri N Romashin、Michael T.H Liu、Roland Bonneau
DOI:10.1016/s0040-4039(00)01911-0
日期:2001.1
a mixture of aryldi(3-chloropropyl)thioacetal and aryl(2-propenyl)(3-chloropropyl)thioacetal in a good yield. The reaction goes through a formation of a sulfur ylide as an intermediate. Rate constants have been determined using laserflash photolytic techniques.