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.
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).
Lewis Acid Catalyzed Conjugate Addition and the Formation of Heterocycles using Michael Acceptors under Solvent-Free Conditions
作者:Alemayehu Mekonnen、Rolf Carlson
DOI:10.1002/ejoc.200500923
日期:2006.4
Conjugate addition and conjugate-addition-initiated ringclosure (CAIRC) reactions of β-dicarbonylcompounds with Michael acceptors have been studied using several Lewis acid catalysts under solvent-free conditions. Excellent chemoselectivity was obtained when various Michael acceptors were treated with several β-dicarbonylcompounds. On the other hand, 2-bromo-2-cyclopentenone and 3-bromo-3-vinyl
Preparation of a microsized cerium chloride-based catalyst and its application in the Michael addition of β-diketones to vinyl ketones
作者:Alexander O. Terent'ev、Vera A. Vil'、Ivan A. Yaremenko、Oleg V. Bityukov、Dmitri O. Levitsky、Vladimir V. Chernyshev、Gennady I. Nikishin、Fabrice Fleury
DOI:10.1039/c3nj01454a
日期:——
evaporation of its alcoholic solutions. The way of the preparation of the cerium chloride-based catalyst plays a decisive role in its catalytic activity. This catalyst is efficient in the Michaeladdition of β-diketones to vinyl ketones giving β,δ-triketones.