N-Bromosuccinimide-dibenzoyl peroxide/azabisisobutyronitrile: a reagent for Z- to E-alkene isomerization
摘要:
N-Bromosuccinimide-dibenzoyl peroxide/azobisisobutyronitrile is used to carry out several types of Z- to E-alkene isomerizations. The NBS-bromination conditions are sufficient for both allylic bromination and alkene isomerization. When the allylic hydrogens are not available in substrates, only the isomerization of the alkene takes place. The present conditions for isomerization of carbon-carbon double bonds are mild and efficient. (C) 2003 Elsevier Ltd. All rights reserved.
An improved procedure for the preparation of substituted 4-hydroxy-4,5-dihydrofurans
作者:Johann Jauch、Volker Schurig
DOI:10.1016/s0040-4039(00)92282-2
日期:1991.1
An improved, highly diastereoselective procedure is described for the preparation of substituted 4-hydroxy-4,5-dihydrofurans 4 which are structural elements that occur in azadirachtin and several other biologically active natural products.
The reactivity of 2-vinylindoles with dimethyl acetylenedicarboxylate
作者:R. Alan Jones、Pilar Martinez Fresneda、Teresa Aznar Saliente、José Sepúlveda Arques
DOI:10.1016/s0040-4020(01)91317-1
日期:1984.1
nes with dimethylacetylenedicarboxylate are considerably lower than those of the corresponding 2-vinyl- pyrroles. Steric interaction between the N-methyl group on the indole ring and the 1-substituent on the ethenyl group prevents the diene system adopting a coplanar configuration and, thereby, inhibits the π4 + π2 cycloaddition reaction of the system with dimethylacetylenedicarboxylate. Under such
Regio- and Stereoselective Intermolecular Hydroalkoxylation of Alkynes Catalysed by Cationic Gold(I) Complexes
作者:Avelino Corma、Violeta R. Ruiz、Antonio Leyva-Pérez、María J. Sabater
DOI:10.1002/adsc.201000094
日期:——
levels of stereoselectivity by using cationic gold(I)‐phosphine complexes as catalysts. By choosing the appropriate phosphine, the selective formation of the Z or the E isomer of the vinyl ether can be tuned, and the undesired formation of the ketal can be controlled. The isomerisation of fumarates (Z‐isomer) to maleates (E‐isomer) is a gold‐catalysed process that can be conducted in one‐pot. When
Organometallic reactions. Part XII. Addition reactions catalysed by organolead compounds
作者:Alwyn G. Davies、R. J. Puddephatt
DOI:10.1039/j39680001479
日期:——
isocyanates. The lead alkoxides also catalyse the trimerisation of isocyanates, and the geometrical isomerisation of esters of maleic, methoxymaleic, and methoxyfumaric acids. The mechanisms of these reactions are discussed.
DABCO catalyzed reaction of various nucleophiles with activated alkynes leading to the formation of alkenoic acid esters, 1,4-dioxane, morpholine, and piperazinone derivatives
作者:Ming-Jin Fan、Gao-Qiang Li、Yong-Min Liang
DOI:10.1016/j.tet.2006.04.100
日期:2006.7
The reaction of acids, alcohols, acylamides, 1,2-diols, 1,2-diamines or amino alcohols with activated alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) was systematically investigated. A series of unsaturated alkenoic acid esters or heterocycles were formed in the reaction of monobasic or dibasic nucleophiles in excellent yields, respectively.