Hydroalumination of silylacetylenes: a novel and highly stereoselective synthesis of (E)-telluro(silyl)ketene acetals and their applications in Sonogashira cross-coupling reactions
作者:Cristiane Y. Kawasoko、Carlos E.D. Nazario、Amanda S. Santana、Luiz H. Viana、Gabriela R. Hurtado、Francisco A. Marques、Gustavo Frensch、Paulo R. de Oliveira、Palimécio G. Guerrero、Diego B. Carvalho、Adriano C.M. Baroni
DOI:10.1016/j.tetlet.2011.08.147
日期:2011.11
alanates intermediates, which were trapped with butyltellurenyl bromide (C4H9TeBr), furnishing exclusively the (E)-1-butyltelluro-1-tri(organyl)silyl-2-organyl-1-alkenes in 45–70% yields. These telluro(silyl)ketene acetals were utilized as substrates in Sonogashira cross-coupling Pd-catalyzed reactions, furnishing the (Z)-1,4-diorganyl-2-tri(organyl)silyl-1-buten-3-ynes with total control of regio- and stereochemistry
用DIBAL-H silylacetylenes的铝氢化,随后加入的Ñ原位产生的(正丁基锂Ž)-β-vinylorganosilane铝氢化物中间体,其被捕获与butyltellurenyl溴化物(C 4 H ^ 9 TeBr),家具完全(ë) -1-丁基telluro-1-三(有机基)甲硅烷基-2-有机基-1-烯烃,产率为45-70%。这些碲(甲硅烷基)乙烯酮缩醛被用作Sonogashira交叉偶联钯催化的反应的底物,从而提供了(Z)-1,4-二有机基-2-三(有机基)甲硅烷基-1-丁烯-3-炔控制区域化学和立体化学的产率为62-80%。
Pd-Catalyzed, Ligand-Enabled Stereoselective 1,2-Iodine(III) Shift/1,1-Carboxyalkynylation of Alkynylbenziodoxoles
A PdII‐catalyzed 2:1 coupling reaction of alkynylbenziodoxole with carboxylic acid to afford (alk‐1‐en‐3‐ynyl)benziodoxole, which is efficiently promoted by an octahydrophenazine ligand, is reported. The reaction involves a Pd‐assisted 1,2‐iodine(III) shift of the alkynylbenziodoxole followed by stereoselective introduction of carboxy and alkynyl groups (the latter originating from another molecule
Treatment of benzyl γ-(trimethylsilyl)propargyl ether with n-BuLi is shown to afford the rarely precedent ortho-[2,3]-Wittig product in remarkable preference to the [1,2]-Wittig product. The factors governing the periselectivity in this type of carbanion rearrangement are discussed.
Diastereoselective Zinco-Cyclopropanation of Chiral Allylic Alcohols with <i>g</i><i>em</i>-Dizinc Carbenoids
作者:Jean-François Fournier、Simon Mathieu、André B. Charette
DOI:10.1021/ja054328+
日期:2005.9.28
allylic alcohols using gem-dizinc carbenoids is described. The reaction produces three contiguous stereogenic centers, and the resulting chiral cyclopropylzinc derivatives can be trapped with electrophiles with retention of configuration. Simple functional group manipulations lead to the efficient synthesis of orthogonally protected 1,2,3-substitutedcyclopropane derivatives.