Selectivity control by silver catalysts in the cycloisomerization of 1,6-enynes derived from propiolamides
摘要:
Silver-catalyzed cycloisomerizations of 1,6-enynes derived from propiolamides led to a selective formation of Alder-ene type 1,4-dienes. Interestingly, AgNTf2 outperformed gold or platinum catalysts in terms of selectivity and reactivity, providing the 1,4-dienes at room temperature. The presence of C(5) carbonyl group in combination with Ag salts is key to the selectivity and the beta-oxo coordinated silver carbenoids were proposed as an intermediate based on the reaction profiles. (C) 2012 Elsevier Ltd. All rights reserved.
Selective ene-yne coupling-functionalization: A new strategy in constructing heterocycles
作者:Zhong Wang、Xiyan Lu
DOI:10.1016/0040-4020(95)00035-7
日期:1995.2
Fluorinated derivatives of 3-alkylidene-2(3H)-dihydrofuranone have been synthesized by sodium dithionite initiated tandem perfluoroalkylation-cyclization of allylic 2-alkynoates in fair to good yield and high stereoselectivity. Fluorinated 3-alkylidene-2(3H)-pyrrolidone derivatives were prepared similarly. A mechanistic rationale concerning the different radical steps and the differences between esters
Structural factors affecting the selectivities in the palladium (II) catalyzed cyclization of N-alkenyl-2-alkynamides
作者:Huanfeng Jiang、Shengming Ma、Guoxin Zhu、Xiyan Lu
DOI:10.1016/0040-4020(96)00648-5
日期:1996.8
Palladiumcatalyzedcyclization of N-alkenyl 2-alkynamides occurred smoothly in the presence of CuCl2 and LiCl affording α-chloroalkylidene-γ-butyrolactams and α-chloroalkylidene-δ-valerolactams valerolactams stereoselectively. The regioselectivity of the intramolecular C-C double bond insertion was influenced by the substituent group on the substrate. When an alkyl group was introduced into the 1'-position
A series of fluoroalkylated 1,4-disubstituted [1,2,3]-triazoles were synthesized by the 1,3-dipolar cycloaddition of fluoroalkylated azides with terminal alkynes in the presence of Cu(I) salt as catalyst at room temperature. All the reactions were performed in highly regioselective with 1,4-disubstituted, no 1,5-disubstituted product was formed. For aryl or alkyl-alkyne, triethylamine should be used
[EN] PROCESS FOR PREPARING N-H OR N-ALKYL 2-PROPYNAMIDE<br/>[FR] PROCÉDÉ DE PRÉPARATION DE N-H- OU N-ALKYL-2-PROPYNAMIDE
申请人:BOEHRINGER INGELHEIM INT
公开号:WO2014037308A1
公开(公告)日:2014-03-13
Disclosed is a method for the synthesis of N-H or N-alkyl 2-propynamides useful as intermediate in the manufacture of pharmaceutically active ingredients.
Hydroiodination of 2-propynamides leading stereoselectively to (Z)-iodopropenamides was achieved under mild conditions at room temperature by the combined use of zinc iodide and tertbutyl iodide. Similarly, the use of zinc bromide in the presence of tert-butyl bromide enabled the synthesis of (Z)-bromopropenamides. (Z)-Halopropenoic esters were also prepared in high yields.