Ruthenium Catalyzed Hydroboration of Terminal Alkynes to Z-Vinylboronates
摘要:
The nonclassical ruthenium hydride pincer complex [Ru(PNP)(H)(2)(H-2)] 1 (PNP = 1,3-bis(di-tert-butyl-phosphinomethyl)pyridine) catalyzes the anti-Markovnikov addition of pinacolborane to terminal alkynes yielding Z-vinylboronates at mild conditions. The complex [Ru(PNP)(H)(2)(HBpin)] 2 (HBpin = pinacolborane), which was identified at the end of the reaction and prepared independently, is proposed as the direct precursor to the catalytic cycle involving rearrangement of coordinated alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration.
作者:Zobernig, Daniel P.、Stöger, Berthold、Veiros, Luis F.、Kirchner, Karl
DOI:10.1021/acscatal.4c03805
日期:——
Mn(I)-catalyzed hydroboration of terminal alkynes with pinacolborane (HBPin) is described. The hydroboration reaction is highly Z-selective in the case of aryl alkynes and E-selective in the case of aliphatic alkynes. The reaction requires no additives or solvents and proceeds with a catalystloading of 1 mol % at 50–70 °C. The most active precatalyst is the bench-stable alkyl Mn(I) complex cis-[Mn(PCP
描述了末端炔烃与频那醇硼烷 (HBPin) 的立体和区域选择性 Mn(I) 催化硼氢化反应。硼氢化反应在芳基炔的情况下具有高度Z-选择性,在脂族炔的情况下具有E-选择性。该反应不需要添加剂或溶剂,催化剂负载量为 1 mol%,反应温度为 50–70 °C。最活跃的预催化剂是工作台稳定的烷基Mn(I)络合物顺式-[Mn(PCP- i Pr)(CO) 2 (CH 2 CH 2 CH 3 )]。通过将CO配体迁移插入M n -烷基键中以产生酰基中间体来引发催化过程。该物质经历炔烃(芳香族炔烃)和 HBPin(脂肪族炔烃)的 C–H 和 B–H 键断裂,形成活性 Mn(I) 炔基和硼基催化剂 [Mn(PCP- i Pr)(CO )(C=CR)]和[Mn(PCP- i Pr)(CO)(BPin)],分别。多种芳香族和脂肪族炔烃被有效且选择性地硼酸化。基于实验数据和 DFT 计算提供了机理见解。官能化烯烃可用于交叉偶联反应中的进一步应用。
Ruthenium Catalyzed Hydroboration of Terminal Alkynes to <i>Z</i>-Vinylboronates
The nonclassical ruthenium hydride pincer complex [Ru(PNP)(H)(2)(H-2)] 1 (PNP = 1,3-bis(di-tert-butyl-phosphinomethyl)pyridine) catalyzes the anti-Markovnikov addition of pinacolborane to terminal alkynes yielding Z-vinylboronates at mild conditions. The complex [Ru(PNP)(H)(2)(HBpin)] 2 (HBpin = pinacolborane), which was identified at the end of the reaction and prepared independently, is proposed as the direct precursor to the catalytic cycle involving rearrangement of coordinated alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration.
Cobalt Catalyzed <i>Z</i>-Selective Hydroboration of Terminal Alkynes and Elucidation of the Origin of Selectivity
作者:Jennifer V. Obligacion、Jamie M. Neely、Aliza N. Yazdani、Iraklis Pappas、Paul J. Chirik
DOI:10.1021/jacs.5b00936
日期:2015.5.13
A bis(imino)pyridine cotalt-catalyzed hydroboration of terminal,,alkynes with HBPin (Pin = pinacolate) with high yield and (Z)selectivity for synthetically valuable vinylboronate esters is described. Deuterium labeling studies Stoichiometric experiments, and isolation of catalytically relevant intermediats support a mechanism involving;selective insertion of,an alkynyl-boronate ester into a Co-H bond, a pathway distinct from known precious metal catalysts, where metal Vinylidene intermediates have been proposed to account for the observed (Z) selectivity. The identity Of the imine substituents dictates the relative rates of activation of the cobalt precatalyst with HBPin or the terminal alkyne and, as a consequence, is responsible for the stereochemical outcome of the catalytic reaction.
Total Synthesis and Structural Validation of Phosdiecin A via Asymmetric Alcohol-Mediated Carbonyl Reductive Coupling
作者:Franco Della-Felice、Ariel M. Sarotti、Michael J. Krische、Ronaldo A. Pilli
DOI:10.1021/jacs.9b07512
日期:2019.9.4
The first total synthesis and structural validation of phosdiecin A was accomplished in 13 steps through asymmetric iridium-catalyzed alcohol-mediated carbonyl reductive coupling. The present route is the shortest among >30 total and formal syntheses of fostriecin familymembers.
phosdiecin A 的首次全合成和结构验证是通过不对称铱催化的醇介导的羰基还原偶联分 13 个步骤完成的。目前的路线是在超过 30 种全合成和正式合成中最短的。