Efficient Synthesis of Functionalized β-Keto Esters and β-Diketones through Regioselective Hydration of Alkynyl Esters and Alkynyl Ketones by Use of a Cationic NHC-Au<sup>I</sup>Catalyst
Regioselective hydration of α-alkynyl esters and ketones by using a cationic NHC–AuI catalyst results in β-keto esters and β-diketones, respectively. Controlled release of water in acetone by aldol self-condensationunder the reaction conditions makes acetone as better solvent than 1,4-dioxane/water for the hydration of α-alkynyl esters having sensitive ester moieties.
A wide range of substituted pyridine derivatives were synthesized in moderate to good yields from a N-propargylic α-enamino ester. The synthetic strategy involves regioselective addition of propargyl amine to the α-carbon of the alkynyl ester to produce N-propargylic α-enamino ester which acts as the key intermediate for the synthesis of the pyridine derivatives.
A copper (I or II)/diethylphosphite catalytic system for base-free additive dimerization of alkynes
作者:Inna G. Trostyanskaya、Irina P. Beletskaya
DOI:10.1016/j.tet.2016.11.073
日期:2017.1
Copper (I) or copper (II) salts and oxides promote regioselective head-to-head additive dimerization of aromatic and aliphatic terminal alkynes in the presence a catalytic amount of diethylphosphite. The reaction proceeds under ambient conditions without any added base with the formation of 1,4-disubstituted 1,3-enynes with the E isomer as major product in good to excellent yields. A plausible mechanism
Stereoselective synthesis of hex-2-(E)-en-4-yn-1,6-dioates and E,Z-muconic acid diesters via organo-catalyzed self-coupling of propiolates
作者:P. Veeraraghavan Ramachandran、Michael T. Rudd、M. Venkat Ram Reddy
DOI:10.1016/j.tetlet.2005.02.098
日期:2005.4
Alkyl propiolate couples with itself in the presence of catalytic DABCO under very mild conditions to provide a quantitative yield of E-hex-2-en-4-yne dioates. Hydrogenation of these enyne dioates using Lindlar catalyst provides the corresponding E,Z-diene dioate, a common structural motif found in an array of natural products.
Synthesis of highly substituted benzene ring systems through three-component coupling of enyne imines, Fischer carbene complexes, and electron-deficient alkynes
作者:Bishnu Dhakal、Lalith S.R. Gamage、Yanshi Zhang、James W. Herndon
DOI:10.1016/j.tetlet.2017.02.070
日期:2017.4
Three-componentcoupling of Fischer carbene complexes, enyne aldehyde hydrazones, and electron-deficient alkynes leads to simple benzoate derivatives in a process involving the formation of an N-aminopyrrole derivative, Diels-Alder reaction, and nitrene extrusion. The products are readily converted into isoquinolones through reaction with primary amines. The reaction proceeds best with highly substituted