We report herein the facile and practical construction of α,β-unsaturatedketones via rhodium-catalyzed direct acylation of vinylsilanes with readily available and abundant carboxylic acids. This protocol features access to a diverse array of synthetically useful functionalities with moderate to excellent yields. More importantly, the late-stage functionalization of pharmaceuticals was also realized
New Tandem Zn-Promoted Brook Rearrangement/Ene−Allene Carbocyclization Reactions
作者:Rozalia Unger、Theodore Cohen、Ilan Marek
DOI:10.1021/ol052237b
日期:2005.11.1
[reaction: see text] A new tandem reaction was developed for the carbocyclization reaction of propargylic zinc reagents. First, we have shown that zinc salt promotes the Brookrearrangement into the carbanionic species followed by a stereospecific Zn-ene-allene carbocyclization reaction to lead to the corresponding cyclopentylmethylzinc derivatives. A single diastereoisomer is formed, even when a tertiary
C-silyl enol ethers or thioenolethers have been prepared by a Peterson reaction, as intermediates for acylsilane synthesis. Bis(trialkylsilyl)(methoxy)- or -(methylsulfanyl)methanes bearing identical or different trialkylsilyl groups were used as starting materials in order to assess the selectivity of the Peterson elimination step. A good selectivity was observed only with ethers bearing the TMS
Methyllithium-Promoted Wittig Rearrangements of α-Alkoxysilanes
作者:Robert E. Maleczka,、Feng Geng
DOI:10.1021/ol990912+
日期:1999.10.1
[formula: see text] The Wittig rearrangements of alpha-alkoxysilanes, promoted by the action of methyllithium were studied. Depending on both the substrate and reaction conditions employed, [2,3]-, [1,2]-, or [1,4]-Wittigrearrangements can be realized. These rearrangements were shown to be initiated by either Si/Li exchange or deprotonation alpha to the silane. Furthermore the sigmatropic shifts can
A Novel Synthesis of (<i>E</i>)-<i>gem</i>-Dimetalloalkenes Containing Boron and Silicon: An Easy Access to Alkyl Trimethylsilyl Ketones
作者:Narayan G. Bhat、Amanda Tamm、Amanda Gorena
DOI:10.1055/s-2004-815399
日期:——
A simple, novelsynthesis of (E)-gem-dimetalloalkenes containing boron and silicon based on (Z)-1-bromo-1-alkenyl-boronate esters is developed. 1-Bromo-(Z)-1-alkenylboronate esters readily available from literature procedures smoothly undergo a reaction with trimethylsilyllithium (easily generated from hexamethyldisilane with methyllithium in hexamethylphosphoramide) to provide the corresponding 'ate'