Preparation of γ,δ-unsaturated-β-ketoesters: Lewis acid-catalysed C H insertion of ethyl diazoacetate into α,β-unsaturated aldehydes
作者:Hirenkumar Gandhi、Timothy P. O'Sullivan
DOI:10.1016/j.tetlet.2017.07.095
日期:2017.9
synthesis of γ,δ-unsaturated-β-keto esters was achieved by the Lewis acid-catalysed direct CH insertion of an α-diazoester into various α,β-substituted-unsaturated aldehydes. CH insertion of ethyldiazoacetate into alkyl- and aryl-substituted α,β-unsaturated aldehydes was performed under mild conditions to afford the corresponding γ,δ-unsaturated-β-keto esters in moderate to high yields as a mixture
are unique units that widely exist in natural products, but the rapid and stereoselective construction of this skeleton is a challenging issue. We report the stereodivergent synthesis of bicyclo[3.2.1]octenes using Nazarov reagents and alkenyl 1,2-diketones with Brønsted base catalysis under mild conditions. Both stereoisomers of the bridged products can be obtained by tuning the reaction conditions,
Rhodium(II)-Catalyzed C–H Functionalization of Electron-Deficient Methyl Groups
作者:Liangbing Fu、David M. Guptill、Huw M. L. Davies
DOI:10.1021/jacs.6b01941
日期:2016.5.11
Enantioselective C-H functionalization of relatively electron-deficient methyl sites was achieved with the combination of 2,2,2-trichloroethyl aryldiazoacetates and tetrakis(triarylcyclopropanecarboxylate) dirhodium catalysts. The substrate scope of the transformation was relatively broad, and C-H functionalization products were furnished with excellent levels of enantioselectivity. As a strategic
1,2-Vinyl and 1,2-Acetylenyl Migration in Rh(II) Carbene Reaction: Remarkable Bystander Effect
作者:Weifeng Shi、Fengping Xiao、Jianbo Wang
DOI:10.1021/jo050173c
日期:2005.5.1
Rh(II)-catalyzed reaction was investigated. 1,2-Migration was the predominant reaction pathway, and the migratory aptitude was found to be dramatically affected by the β-substituents. The 1,2-vinyl and 1,2-acetylenyl group migration occurs preferentially in the presence of β-hydrogen in Rh2(OAc)4-catalyzed reaction of β-(trichloroacetyl)amino α-diazo carbonyl compounds. A possible reaction mechanism is discussed