Cooperative organocatalysis of Mukaiyama-type aldol reactions by thioureas and nitro compounds
作者:Konstantin V. Bukhryakov、Victor G. Desyatkin、Valentin O. Rodionov
DOI:10.1039/c6cc01984f
日期:——
A unique organocatalytic system for Mukaiyama-type aldol reactions based on the cooperative action of nitrocompounds and thioureas has been identified. This system is compatible with a wide range of...
Conjugate addition of O-silylatedketeneacetals to α,β-unsaturated carbonyl compounds in acetonitrile gave quantitative yields of the corresponding β-(alkoxycarbonyl)methyl O-silyl enolates . Site specific electrophilic substitutions of yielded the corresponding α-substituted β-(alkoxycarbonyl)-methylalkanones , , and .
these reactions. Enhanced preference for the more sterically demanding Michael adducts is obtained with Bu(2)Sn(OTf)(2), SnCl(4), and Et(3)SiClO(4) in the former reaction while TiCl(4) gives the highest selectivity for the less sterically demanding products in the latter case. These results are interpreted in terms of alternative reaction mechanisms. The reaction of less bulky ketene silyl acetals are
Tandem Mukaiyama Michael–aldol reactions catalysed by samarium diiodide
作者:Nicolas Giuseppone、Jacqueline Collin
DOI:10.1016/s0040-4020(01)00902-4
日期:2001.10
Samarium diiodide is an efficient precatalyst for tandemMichael–aldolreactions, which allow the formation of two carbon–carbon bonds by successive additions of a ketene silyl acetal and an aldehyde on cyclic α,β-unsaturated ketones. The adducts are isolated as silyl ethers, in good yields, and in some cases with high diastereoselectivities when the reactions are performed at low temperatures. Comparative
Indium-Mediated β-Allylation, β-Propargylation, and β-Allenylation onto α,β-Unsaturated Ketones: Reactions of in-Situ-Generated 3-<i>tert</i>-Butyldimethylsilyloxyalk-2-enylsulfonium Salts with in-Situ-Generated Organoindium Reagents
作者:Kooyeon Lee、Hyunseok Kim、Tomoya Miura、Koichi Kiyota、Hiroyuki Kusama、Sunggak Kim、Nobuharu Iwasawa、Phil Ho Lee
DOI:10.1021/ja035988m
日期:2003.8.1
onium salts, generated in situ from the reaction of alpha,beta-enones with dimethyl sulfide in the presence of TBSOTf, underwent a novel nucleophilic substitution with allylindiums to give silyl enol ethers of delta,epsilon-alkenyl ketones in good yields, which correspond to formal Michael addition products. In a similar manner, 1,4-propargylation of propargylindiums onto the sulfoniumsalts produced