Introduction of Electrophiles to the α-Position of α,β-Unsaturated Aldehydes and Ketones by Sequential Conjugate Aminosilylation-Alkylation-Deamination
Silylamines add to α,β-unsaturated aldehydes and ketones in 1,4-addition mode to generate amino-substituted silyl enolethers without any catalysts. These easily isolable silyl enolethers react with acetals and aldehydes in the presence of a Lewisacid to give α-alkoxyalkyl and α-hydroxyalkyl substitutedα,β-unsaturatedcarbonylcompounds, respectively, after deamination by treatment with silica gel
Trimethysilyl triflate in organic synthesis11Part 11 of this series. Part 10: S. Murata and R. Noyori, Tetrahedron Letters 2107 (1981).
作者:R. Noyori、S. Murata、M. Suzuki
DOI:10.1016/s0040-4020(01)93263-6
日期:——
Trimethylsilyl triflate is a powerful silylating agent for organic compounds and acts as a catalyst which accelerates a variety of nucleophilic reactions in aprotic media. The reactions proceed via one-center, electrophilic coordination of the silyl group to hetero functional groups and exhibit unique selectivities.
2-alkylidenecyclohexanone from 3-oxymethyl-2-siloxy-1,3-butadienes, which can be prepared from Baylis-Hillman adducts, and alpha,beta-unsaturated ketones is described. The process involves two mechanistically distinct reactions, (4+2) cycloaddition and elimination. Both of these reactions are catalyzed by Tf(2)NH.
The ability of the combination of sulfide/TBDMSOTf to promote a chalcogenide-Morita-Baylis-Hillman reaction is reported. The original Michael-Mukaiyama-retroaldol sequence took place and furnished the MBH adducts from the corresponding enones and acetals. This one step process could be performed smoothly at low temperatures (-20 to -50 degrees C) and is rapidly completed within a few hours. (c) 2006 Elsevier Ltd. All rights reserved.
A new procedure for α-alkoxyalkylation of α,β -unsaturated ketones