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.
A highlyefficient cyanosilylation protocol mediated by the easily available n-BuLi with a wide range of aldehydes and ketones was developed. This protocol features excellent yields with very low n-BuLi loadings (0.01–0.05 mol%) at room temperature, solvent-free process, good chemo-/regio-selectivity and functional group tolerance and scalability. A possible reaction pathway based upon stoichiometric
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
Two aryl amino borinium cations derived from Cl(Mes)B-NR2 (NR2 = TMP, HMDS) faced divergent outcomes. As the HMDS-substituted one underwent methylmigration from silicon to boron transforming the putative borinium ion to a silylium ion, [Mes-B-TMP]+ can initiate cyanosilylation and catalyse hydrosilylation of ketones and aldehydes.
Thermolysis of Acylazo <i>O</i>-Trimethylsilyl Cyanohydrins: Azoalkanes Yielding Captodatively Substituted Radicals
作者:Charles F. Billera、Travis B. Dunn、David A. Barry、Paul S. Engel
DOI:10.1021/jo981372h
日期:1998.12.1
A new synthetic method has been developed for preparing azoalkanes bearing geminal ol-cyano and alpha-trimethylsiloxy groups. While the symmetrical compound 5 decomposes near room temperature to afford, almost entirely, the C-C dimers, the unsymmetrical azoalkane 3 requires heating to 75 degrees C. The thermolysis activation parameters of 3 and 5 can be rationalized on steric grounds without invoking captodative radical stabilization. A C-13 NMR product study of photolyzed 3 in the presence of TEMPO at 21 degrees C shows that the fate of caged [tert-butyl, 1-trimethylsiloxy-1-cyanoethyl(14)] radical pairs is disproportionation, 17%, cage recombination, 20%, and cage escape, 63%.