Michael Reaction of Stabilized Carbon Nucleophiles Catalyzed by [RuH<sub>2</sub>(PPh<sub>3</sub>)<sub>4</sub>]
作者:Enrique Gómez-Bengoa、Juan M. Cuerva、Cristina Mateo、Antonio M. Echavarren
DOI:10.1021/ja961373w
日期:1996.1.1
also observed as side reactions. Catalysis by other ruthenium and rhodium complexes has been examined. Selectivity studies performed with malonate and disulfone donors indicate that the catalyst selectively activates Michael donors that can coordinate with ruthenium(II). Additionally, it has been shown that the reaction requires the presence of free phosphine. Therefore, the Michael reaction of stabilized
缺乏氰基的活性亚甲基化合物如丙二酸酯、β-酮酯、1,3-二酮、1,1-二砜、硝基化合物、Meldrum 酸和蒽酮与常见受体的迈克尔反应在乙腈溶液中在 [RuH2 (PPh3)4]作为催化剂。氰基乙酸盐在有机溶剂中比丙二酸盐酸性更强,也是该反应的极好底物。在许多情况下,也观察到由 [RuH2(PPh3)4] 催化的分子内羟醛反应作为副反应。已经研究了其他钌和铑配合物的催化作用。对丙二酸和二砜供体进行的选择性研究表明,该催化剂选择性地激活可以与钌 (II) 配位的迈克尔供体。此外,已经表明该反应需要存在游离膦。所以,稳定的烯醇化物的迈克尔反应似乎是钌和膦催化的反应。从实用的角度来看,使用随手准备...
Sodium Tetramethoxyborate: An Efficient Catalyst for Michael Additions of Stabilized Carbon Nucleophiles
作者:Araceli G. Campaña、Noelia Fuentes、Enrique Gómez-Bengoa、Cristina Mateo、J. Enrique Oltra、Antonio M. Echavarren、Juan M. Cuerva
DOI:10.1021/jo701354c
日期:2007.10.1
[GRAPHICS]Sodium tetramethoxyborate, easily prepared by reaction of inexpensive sodium borohydride with methanol, possesses a suitable combination of a Lewis base and a Lewis acid to catalyze Michael reactions at room temperature under practically neutral conditions. This reaction provides good to excellent yields of Michael addition products from a broad scope of Michael donor and Michael acceptor reagents.
Cyclization Reactions Leading to β-Hydroxyketo Esters
作者:Jesse M. Nicholson、Ivan O. Edafiogho、Jacqueline A. Moore、Vida A. Farrar、K.R. Scott
DOI:10.1002/jps.2600830118
日期:1994.1
the research was to synthesize β-diketo esters and to evaluate them for anticonvulsant activity. The reaction of methyl vinyl ketone with dimethyl malonate in the presence of potassium carbonate gave an uncyclized product that underwent a Clalsen condensation to yield methyl 2-hydroxy-4-oxocyclohex-2-en- 1-oate (5a). Similarly, other cyclized β-hydroxyketo esters were prepared, and their spectrometric
Phosphine-boronates R(2)P(o-C(6)H(4))B(OR')(2) have been evaluated as bifunctionalorganocatalysts for the Michaeladdition of malonate pronucleophiles to methylvinylketone. The presence of the Lewis acidic boron center adjacent to phosphorus significantly improves catalytic performance. Isolation and complete characterization of a key intermediate, namely a beta-phosphonium enolate, substantiate the