MatPhos,是完成艰苦任务的理想伴侣:迄今为止,由于中等ee值和低活性,阻碍了1-烷基乙烯基酯的不对称氢化,现在可以使用ee值为96–99%的MatPhos / Rh催化剂来实现在低催化剂负载量(0.1-1 mol%)和温和条件(5-20 bar H 2,室温)下制备底物。水解后,可以高对映体纯度获得相应的手性仲烷基醇,为获得这一重要产品类别提供了一条通用而实用的途径。
MatPhos,是完成艰苦任务的理想伴侣:迄今为止,由于中等ee值和低活性,阻碍了1-烷基乙烯基酯的不对称氢化,现在可以使用ee值为96–99%的MatPhos / Rh催化剂来实现在低催化剂负载量(0.1-1 mol%)和温和条件(5-20 bar H 2,室温)下制备底物。水解后,可以高对映体纯度获得相应的手性仲烷基醇,为获得这一重要产品类别提供了一条通用而实用的途径。
The Rh(III)-catalyzed C–H activation initiated cyclization of benzoicacids with electron-rich geminal-substituted vinyl acetates was described. The reaction was employed to prepare a range of 3-aryl and 3-alkyl substituted isocoumarins selectively.
ligand not only can facilitate the electrophilic aryl C–H rhodation but also can lower the olefin insertion barrier. Both electron-withdrawing and electron-donating directing groups such as -CONR2 and -NHAc could be employed in these reactions, which provides convenient routes toward a series styryl acetates, N-acetylindoles, and aryl methyl ketones.
尽管对过渡金属催化的Fujiwara–Moritani C–H型烯烃进行了广泛的研究,但这些转化中使用的烯烃仍主要限于活性丙烯酸酯和苯乙烯。富电子烯烃的选择性芳基CH烯化反应被认为是一个具有挑战性的问题。我们在本文中报道,简单且易于接近的缺电子的[CpRh(III)]和[Cp CF 3 Rh(III)](Cp CF 3 = C 5 Me 4 CF 3)配合物是富电子脱氢芳基化的有力催化剂烯烃,包括乙酸乙烯酯,酰胺和乙烯基醚。使用吸电子Cp或Cp CF 3配体代替特权Cp *(C5 Me 5)配体不仅可以促进亲电芳基C–H的铑基化,而且可以降低烯烃的插入势垒。在这些反应中都可以使用吸电子和供电子导向基团,例如-CONR 2和-NHAc,这提供了通向一系列乙酸苯乙烯酯,N-乙酰吲哚和芳基甲基酮的便捷途径。
Ruthenium complex catalyzed selective addition of carboxylic acids to acetylenes giving enol esters
Carboxylic acids react with acetylenes in the presence of a catalytic amount of bis(η5-cyclooctadienyl)ruthenium-PR3-maleic anhydride in toluene to give enol esters in good to excellent yields with high regioselectivity.
Enantioselective Rh-Catalyzed Hydrogenation of Vinyl Carboxylates with Monodentate Phosphite Ligands
作者:Manfred T. Reetz、Lukas J. Goossen、Andreas Meiswinkel、Jens Paetzold、Jakob Feldthusen Jensen
DOI:10.1021/ol035076p
日期:2003.8.1
[reaction: see text] Alkyl-substituted vinylcarboxylates, which normally show poor enantioselectivity in Rh-catalyzed hydrogenation with traditional chiral diphosphines, undergo highly enantioselective reactions with BINOL- and carbohydrate-based monophosphite ligands.
A rapid and efficient method is described for the selective synthesis of enol esters via the microwave-accelerated addition of carboxylic acids to terminal alkynes. The method employs the readily available [RuCl2(p-cymene)(PPh3)] complex as catalyst without the need of bases, and reactions are complete in 20 min.