Electrogenerated Acid-Catalyzed Reactions of Acetals, Aldehydes, and Ketones with Organosilicon Compounds, Leading to Aldol Reactions, Allylations, Cyanations, and Hydride Additions
electrogenerated acid (EG acid) in the silicon-mediated acid-catalyzed reactions; e.g., aldol reactions, allylations, cyanations, and hydride additions is described. The aldol reaction of acetals 1 with enol trimethylsilyl ethers 3 and 1,2-bis(trimethylsiloxy)alkenes 4 gives the corresponding adducts 5 and 6, respectively. The reaction proceeds smoothly with EG acid derived from perchlorate salts such
Inorganic/Organic Salts as Heterogeneous Basic Catalysts for Cyanosilylation of Carbonyl Compounds
作者:Xiaoming Feng、Bin He、Yan Li、Guolin Zhang
DOI:10.1055/s-2004-829569
日期:——
The addition of TMSCN to carbonyl compounds catalyzed by K2CO3 as heterogeneous catalyst gave the corresponding cyanohydrin trimethylsilyl ethers from 20 minutes to 24 hours with 62% to 99% yields without solvent at room temperature. Moreover, it was found that chiral organic salts as heterogeneous catalysts also can catalyze the asymmetric version and afford the corresponding products with up to 99% yield and 12.4% ee.
Catalytic Asymmetric Cyanosilylation of Ketones with Chiral Lewis Base
作者:Shi-Kai Tian、Ran Hong、Li Deng
DOI:10.1021/ja036222p
日期:2003.8.1
catalytic approaches for the enantioselective creation of quaternary stereocenters remains a highly desirable yet challenging goal. In this Communication, we describe a highlyenantioselective cyanosilylation of acetal ketones (alpha,alpha-dialkoxy ketones) catalyzed by modified cinchona alkaloids. This reaction is the first highlyenantioselective cyanosilylation of ketones catalyzed by an organic chiral
catalysis promises high catalytic efficiency in the enantioselectivecyanosilylation of ketones through the combined use of a Lewis acid and a Lewis base. Catalyst systems composed of a chiral salen-Al complex and an N-oxide have high catalytic turnovers (200 for aromatic ketones, 1000 for aliphatic ones). With these catalysts, a wide range of aliphatic and aromatic ketones were converted under mild
Lewis Acid Rather than Brønsted Acid Sites of Montmorillonite K10 Act as a Powerful and Reusable Green Heterogeneous Catalyst for Rapid Cyanosilylation of Ketones
A practical green protocol was developed for highlyefficientcyanosilylation of various ketonescatalyzed by commercial montmorillonite K10, with excellent isolated yields (91–99%). The catalyst can be used as received, and its catalytic strength can be easily restored without loss of activity. Investigations of catalyst recycling and of the active catalytic sites indicated that Lewis acid sites were