Regioselective α-benzylation of 3-iodoazetidine via Suzuki cross-coupling
摘要:
An efficient protocol for the synthesis of alpha-benzyl azetidines starting from benzylboronic acid pinacol ester derivatives and 3-iodoazetidine was developed. A wide range of alpha-benzyl azetidine derivatives were obtained in moderate to good yields with high regioselectivity (>99%). (C) 2019 Elsevier Ltd. All rights reserved.
STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
申请人:The University of Chicago
公开号:US20180361370A1
公开(公告)日:2018-12-20
Metal-organic framework (MOFs) compositions based on post¬synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH
2
groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
Iridium-Catalyzed Borylation of Primary Benzylic C–H Bonds without a Directing Group: Scope, Mechanism, and Origins of Selectivity
作者:Matthew A. Larsen、Conner V. Wilson、John F. Hartwig
DOI:10.1021/jacs.5b04899
日期:2015.7.8
Primary benzylic boronate esters are useful intermediates in organic synthesis, but these reagents cannot be prepared by hydroboration. The benzylic C-H borylation of methylarenes would be a method to form these products, but such reactions without neat methylarene or a directing group are unknown. We report an approach to divert the borylation of methylarenes from aromatic positions to benzylic positions
主要的苄基硼酸酯是有机合成中有用的中间体,但这些试剂不能通过硼氢化反应制备。甲基芳烃的苄基 CH 硼酸化将是形成这些产物的一种方法,但这种没有纯甲基芳烃或导向基团的反应是未知的。我们报告了一种以甲硅烷基硼烷为试剂和含有缺电子菲咯啉作为配体的新型铱催化剂将甲基芳烃的硼酸化从芳族位置转移到苄位位置的方法。该系统相对于相应的芳基硼酸酯选择性地形成苄基硼酸酯。由菲咯啉连接的 Ir 二硼基单甲硅烷基复合物被分离并确定为催化剂的静止状态。机理研究表明,这种复合物在动力学上有能力成为催化过程中的中间体。各种 Ir 配合物催化的苄基和芳基 CH 硼化的动力学研究表明,芳基 CH 硼化速率随着 Ir 催化剂金属中心电子密度的降低而降低,但苄基 CH 硼化速率对Ir 催化剂金属中心的电子密度。动力学和计算研究表明,这两种硼酸化反应对金属中心的电子密度程度的反应不同,因为它们发生在不同的转换限制步骤中。已知芳基
Cobalt-Catalyzed Benzylic Borylation: Enabling Polyborylation and Functionalization of Remote, Unactivated C(sp<sup>3</sup>)–H Bonds
作者:W. Neil Palmer、Jennifer V. Obligacion、Iraklis Pappas、Paul J. Chirik
DOI:10.1021/jacs.5b12249
日期:2016.1.27
have been synthesized and demonstrated as active for the C(sp(3))-H borylation of a range of substituted alkyl arenes using B2Pin2 (Pin = pinacolate) as the boron source. At longer reaction times, rare examples of polyborylation were observed, and in the case of toluene, all three benzylic C-H positions were functionalized. Coupling benzylic C-H activation with alkyl isomerization enabled a base-metal-catalyzed
Cobalt-Catalyzed C–H Borylation of Alkyl Arenes and Heteroarenes Including the First Selective Borylations of Secondary Benzylic C–H Bonds
作者:Chathurika R. K. Jayasundara、Dmitrijs Sabasovs、Richard J. Staples、Jossian Oppenheimer、Milton R. Smith、Robert E. Maleczka
DOI:10.1021/acs.organomet.8b00144
日期:2018.5.29
A cobalt di-tert-butoxide complex bearing N-heterocyclic carbene (NHC) ligands has been synthesized and characterized. This complex is effective at catalyzing the selective monoborylation of the benzylic position of alkyl arenes using pinacolborane (HBpin) as the boron source. This same cobalt complex enables selective monoborylation of N-methylpyrrole, N-methylpyrazole, and N-methylindole. Catalysis
Borylation at the benzylic C–H bond of alkylbenzenes with bis(pinacolato)diboron [(Me4C2O2)B–B(O2C2Me4)] or pinacolborane [(Me4C2O2)B–H] was carried out at 100 °C in the presence of a catalytic amount of 10% Pd/C. The reaction selectively afforded pinacol benzylboronates in good yields directly from various alkylbenzenes.