Copper-Catalyzed Enantiotopic-Group-Selective Allylation of <i>gem</i>-Diborylalkanes
作者:Minjae Kim、Bohyun Park、Minkyeong Shin、Suyeon Kim、Junghoon Kim、Mu-Hyun Baik、Seung Hwan Cho
DOI:10.1021/jacs.0c11750
日期:2021.1.20
We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination of copper(I) bromide and H8-BINOL derived phosphoramidite ligand proved to be the most effective catalytic system to provide various enantioenriched homoallylic boronate esters, containing a boron-substituted stereogenic center that is solely derived from gem-diborylalkanes
Pd-catalyzed cascade reactions involving skipped dienes: from double carbopalladation to remote C–C cleavage
作者:Hamid Azizollahi、Vaibhav P. Mehta、José-Antonio García-López
DOI:10.1039/c9cc04817k
日期:——
We report two ligand-controlled cascade reactions relying on the intramolecular carbopalladation of skipped dienes. The use of a bulky monodentate phosphine ligand affords [4,5]-spirocycles via sequential double carbopalladation, however bidentate phosphines promote a remote β-C-elimination process which does not rely on the use of strained or sterically hindered substrates.
Stereoselective Control of the Cu Activation of β,β-Diboryl Acrylates for Allylic Coupling Protocols with Concomitant Lactonization
作者:Mireia Pujol、María Méndez、Elena Fernández
DOI:10.1021/acs.orglett.3c03640
日期:2024.4.12
discriminate between two geminal boryl moieties that are exposed to the same reaction conditions. Here we describe a stereoselective C–B activation of β,β-diboryl acrylates forming exclusively the (Z)-α-borylalkenyl copper(I) key intermediate, for subsequent allylic alkylation reactions. The new borylated (Z)-skipped dienoates followed a feasible iodo-lactonization sequence for the preparation of borylated
成功 C-B 活化的关键是区分暴露于相同反应条件的两个偕硼基部分。在这里,我们描述了β,β-二硼基丙烯酸酯的立体选择性C-B活化,仅形成( Z )-α-硼基烯基铜(I)关键中间体,用于随后的烯丙基烷基化反应。新的硼酸化( Z )-跳过的二烯酸酯遵循可行的碘内酯化顺序来制备硼酸化内酯核心,其可用于药物发现。
Highly selective trapping of unsymmetrical pentadienyl anions by silicon and tin electrophiles. Marked contrast between kinetic and thermodynamic control of product composition
The nucleophilic reaction of lithium and potassium salts of five pentadienyl anions bearing sterically and/or coordinatively different groups at their unsymmetrical 2-position toward Me3SiCl and Me3SnBr is described. When the anion of the potassium salt was trapped by Me3SiCl, (Z)-4-substituted-pentadienylsilanes were obtained with high selectivity (87-100%). The lithium salt, however, gave a mixture of (E)- and (Z)-4-substituted-pentadienylsilanes. The coupling reaction proceeds under kinetic control, because the product composition from Si trapping reflected the structure of the parent dienyl anion and the steric interaction between the incoming Me3Si group and the substituent on the anion. In contrast, when the anion was trapped by Me3SnBr under the identical conditions, (Z)-2-substituted-pentadienyltins were formed with 60-96% selectivity. Only relatively small changes in product composition, as a function of the cation or the substituent on the anion, were observed. These results could be explained by thermodynamic controlling factors, including a 1,5-Me3Sn shift, and a redistribution of pentadienyl groups under basic conditions.
The seriatim Cu(I) activation of 1,1,1′,1′-tetrapinacolborylethane to prospective ring closing
作者:Sara González、Dario Del Carratore、Ricardo J. Maza、Elena Fernández