在此,我们报道了由镍分子催化剂介导的碳酸炔丙酯催化还原为丙二烯。该催化系统使用光作为驱动力,胺作为唯一的氢源。与其他催化方法相反,该过程的进行无需金属氢化物物质的中介。过渡金属催化还原过程中常见的途径被涉及一系列电子转移和质子转移的途径所取代。使用这种催化方法,可以在温和条件下获得多种丙二烯。实验研究支持三烷基胺作为还原剂和质子源的双重作用,并揭示了该反应的关键机理特征。提出了Ni( II ) 联烯基中间体的关键原脱镍步骤来解释还原过程。最后,我们还证明选择性 S N 2 ' 还原过程也可以通过电化学方法有效驱动。
Catalytic Enantioselective Synthesis of β-Allenyl Boronic Esters by Conjunctive Cross-Coupling with Propargylic Carbonates
作者:Mark D. Aparece、Weipeng Hu、James P. Morken
DOI:10.1021/acscatal.9b04453
日期:2019.12.6
Enantioselectiveconjunctivecross-coupling with propargylic carbonates affords β-boryl allenes as the reaction product. The reaction is found to proceed through the intermediacy of dimethoxyboronate complexes that are generated in situ by a strain-induced ligand exchange reaction.
Domino C–H Activation/Directing Group Migration/Alkyne Annulation: Unique Selectivity by d<sup>6</sup>-Cobalt(III) Catalysts
作者:Cuiju Zhu、Rositha Kuniyil、Becky B. Jei、Lutz Ackermann
DOI:10.1021/acscatal.9b05413
日期:2020.4.3
control in Cp*CoIII-catalyzed domino C–Hactivation/pyridine directing group migration/alkyne annulation has been accomplished through the nucleophilicity of an organometallic cobalt intermediate with a d6 electron configuration. Detailed mechanistic studies provided compelling evidence for a facile C–Hactivation along with a favorable migration of the directing group for the Cp*CoIII catalysis, rather
通过具有ad 6电子构型的有机金属钴中间体的亲核性,完成了Cp * Co III催化的多米诺骨牌CH-H活化/吡啶引导基团迁移/炔烃环化反应中的不同选择性控制。详细的机理研究提供了令人信服的证据,证明了C–H的活化很容易,并且Cp * Co III催化的导向基团有良好的迁移,而不是(CO)3 Mn I歧管观察到的β-氧消除。
Ag(I)-Catalyzed Nucleophilic Addition and Friedel–Crafts Alkylation between α-Oxoketene Dithioacetals and Propargyl Carbonates
作者:Manman Wang、Dachang Bai、Lingheng Kong、Bingxian Liu、Xingwei Li
DOI:10.1021/acs.orglett.8b03180
日期:2018.12.21
Silver-catalyzed nucleophilic addition and intramolecular Friedel–Crafts alkylation between α-oxoketenedithioacetals and tertiary propargylic carbonates have been realized. The reactions proceeded in moderate to good yields with broad substrate scope, providing a straightforward method for the synthesis of substituted indenes.
A Straightforward Synthesis of Cyclobutenones via a Tandem Michael Addition/Cyclization Reaction of 2,3-Allenoates with Organozincs
作者:Guobi Chai、Shangze Wu、Chunling Fu、Shengming Ma
DOI:10.1021/ja1108694
日期:2011.3.23
polysubstituted cyclobutenones, which are not readily available from traditional methods due to the intrinsic ring strain, is described. The reaction of 2,3-allenoates and organozinc reagents proceeds via a tandem Michael addition/cyclic 1,2-addition/elimination mechanism with the functional groups from the organozinc reagents being introduced to the 3-position of the cyclobutenone products regiospecifically