Substituent effects on the13C NMR spectra of ethylcis- andtrans-2-(p-substituted-phenyl)-1-cyclopanecarboxylates
作者:Yoshiaki Kusuyama、Kenjiro Tokami
DOI:10.1002/mrc.1260300415
日期:1992.4
13C NMR spectra were measured for a series of ethyl cis- and trans-2-(p-substituted - phenyl) - 1 - cyclopropanecarboxylates. The effects of the para substituents and the geometry on the chemical shifts are discussed.
Cyclopropanation of alkenes with metallocarbenes generated from monocarbonyl iodonium ylides
作者:Tristan Chidley、Graham K. Murphy
DOI:10.1039/c8ob02636j
日期:——
Reacting Wittigreagents and the hypervalent iodine reagent iodosotoluene, in the presence of 10 mol% Cu(tfacac)2 and 5 equiv. of alkene, results in a novel cyclopropanation reaction. The reagent combination is believed to generate a transient monocarbonyliodoniumylide (MCIY) in situ, which can be intercepted by the copper catalyst to give a metallocarbene. Both ester and ketone derived phosphoranes
The first examples of heterogeneous Fe-catalysed cyclopropanation reactions are presented. Pyrolysis of in situ-generated iron/phenanthroline complexes in the presence of a carbonaceous material leads to specific supported nanosized iron particles, which are effective catalysts for carbene transfer reactions. Using olefins as substrates, cyclopropanes are obtained in high yields and moderate diastereoselectivities
介绍了非均相 Fe 催化的环丙烷化反应的第一个例子。在含碳材料的存在下原位生成的铁/菲咯啉配合物的热解产生特定的负载纳米铁颗粒,这是卡宾转移反应的有效催化剂。使用烯烃作为底物,以高产率和中等非对映选择性获得环丙烷。所开发的协议是可扩展的,并且在温和条件下使用氧化再活化协议可以有效地恢复失活后回收催化剂的活性。
Ruthenium–arene catalysts bearing N-heterocyclic carbene ligands for olefin cyclopropanation and metathesis
作者:Michaël Méret、Anna M. Maj、Albert Demonceau、Lionel Delaude
DOI:10.1007/s00706-015-1492-x
日期:2015.7
AbstractRuthenium–arene complexesbearing N-heterocyclic carbene (NHC) ligands with the generic formula [RuCl2(p-cymene)(NHC)] are efficient catalyst precursors for the cyclopropanation of activated olefins with ethyl diazoacetate, and the cis/trans diastereoselectivity of the reaction markedly depends on the steric bulk of the NHC. The procedure was successfully applied to styrene, α-methylstyrene
A de novo peroxidase is also a promiscuous yet stereoselective carbene transferase
作者:Richard Stenner、Jack W. Steventon、Annela Seddon、J. L. Ross Anderson
DOI:10.1073/pnas.1915054117
日期:2020.1.21
activity extends to the efficient and stereoselective intermolecular transfer of carbenes to olefins, heterocycles, aldehydes, and amines. Not only is this a report of carbene transferase activity in a completely de novo protein, but also of enzyme-catalyzed ringexpansion of aromatic heterocycles via carbene transfer by any enzyme.