Thomas Bryce N, Moon Patrick J, Yin Shengkang, Brown Alex, Lundgren Rylan J
Department of Chemistry , University of Alberta , Edmonton , Alberta T6G 2G2 , Canada . Email:
Chem Sci. 2017 Oct 24;9(1):238-244. doi: 10.1039/c7sc04283c. eCollection 2018 Jan 7.
A well-defined Ir-allyl complex catalyzes the -selective cross-coupling of allyl carbonates with α-aryl diazo esters. The process overrides the large thermodynamic preference for -products typically observed in metal-mediated coupling reactions to enable the synthesis of ,-dieneoates in good yield with selectivities consistently approaching or greater than 90 : 10. This transformation represents the first productive merger of Ir-carbene and Ir-allyl species, which are commonly encountered intermediates in allylation and cyclopropanation/E-H insertion catalysis. Potentially reactive functional groups (aryl halides, ketones, nitriles, olefins, amines) are tolerated owing to the mildness of reaction conditions. Kinetic analysis of the reaction suggests oxidative addition of the allyl carbonate to an Ir-species is rate-determining. Mechanistic studies uncovered a pathway for catalyst activation mediated by NEt.
一种明确的铱-烯丙基配合物催化碳酸烯丙酯与α-芳基重氮酯的 -选择性交叉偶联反应。该过程克服了在金属介导的偶联反应中通常观察到的对 -产物的巨大热力学偏好，能够以良好的产率合成 ,-二烯酸酯，选择性始终接近或大于90:10。这种转化代表了铱-卡宾和铱-烯丙基物种的首次有效合并，它们是烯丙基化和环丙烷化/E-H插入催化中常见的中间体。由于反应条件温和，潜在的反应性官能团（芳基卤化物、酮、腈、烯烃、胺）能够耐受。反应的动力学分析表明碳酸烯丙酯向铱物种的氧化加成是速率决定步骤。机理研究揭示了由NEt介导的催化剂活化途径。
