Cerium(III) chloride heptahydrate in the presence of sodium iodide catalyses the Michael addition of 1,3-dicarbonyl compounds to α,β-unsaturated ketones and α,β-unsaturated aldehydes with extraordinary efficiency. The very mild conditions allow high chemoselectivity as shown by the absence of the typical side reactions, which can be observed in the conventional base-catalyzed processes. More interestingly
Long chain dicationic ammonium salts (1a-1c), easily prepared from tert-amines and dihaloalkanes, were successfully used as efficient phase-transfer catalysts in the Michael addition reaction of various active methylene compounds to 2-cyclohexenone without solvent under ultrasonic irradiation. The investigated dicationic salts were more effective than monocationic tetrabutylammonium bromide, with short reaction times and high yields. This methodology was established under phase-transfer catalytic conditions and ultrasonic effects with many advantages, including the easy and cost-effective synthesis of the catalyst, mild reaction conditions, short reaction times, good yields, simple work-up procedures, and environmental friendliness.
Ionic Liquid as Catalyst and Reaction Medium. The Dramatic Influence of a Task-Specific Ionic Liquid, [bmIm]OH, in Michael Addition of Active Methylene Compounds to Conjugated Ketones, Carboxylic Esters, and Nitriles
作者:Brindaban C. Ranu、Subhash Banerjee
DOI:10.1021/ol051004h
日期:2005.7.1
[reaction: see text] A task-specific ionicliquid, [bmIm]OH, has been introduced as a catalyst and as a reactionmedium in Michael addition. Very interestingly, although the addition to alpha,beta-unsaturated ketones proceeds in the usual way, giving the monoaddition products, this ionicliquid always drives the reaction of open-chain 1,3-dicarbonyl compounds with alpha,beta-unsaturated esters and
Ionic liquid as catalyst and solvent: the remarkable effect of a basic ionic liquid, [bmIm]OH on Michael addition and alkylation of active methylene compounds
作者:Brindaban C. Ranu、Subhash Banerjee、Ranjan Jana
DOI:10.1016/j.tet.2006.10.077
日期:2007.1
ketones, carboxylic esters and nitriles. It further catalyzes the addition of thiols to α,β-acetylenic ketones and alkylation of 1,3-dicarbonyl and -dicyano compounds. The Michael addition to α,β-unsaturated ketones proceeds in the usual way, giving the monoaddition products, whereas addition to α,β-unsaturated esters and nitriles leads exclusively to the bis-addition products. The α,β-acetylenic ketones
The Michael reaction, with conjugate bases of β-diketones as donors and with α,β-unsaturatedketones as acceptors, is efficiently catalyzed by a combination of clay-supported nickel bromide (heterogeneous) and ferric chloride (homogeneous).