Rh(I)-Catalyzed [5 + 1] Cycloaddition of Vinylcyclopropanes and CO for the Synthesis of α,β- and β,γ-Cyclohexenones
摘要:
A cationic Rh(I)-catalyzed [5 + 1] cycloaddition of vinylcyclopropanes and CO has been developed, affording either beta,gamma-cyclohexenones as major products or alpha,beta-cyclohexenones exclusively, under different reaction conditions.
Reductive Cyclopropanations Catalyzed by Dinuclear Nickel Complexes
作者:You-Yun Zhou、Christopher Uyeda
DOI:10.1002/anie.201511271
日期:2016.2.24
Dinuclear Ni complexes supported by naphthyridine‐diimine (NDI) ligands catalyze the reductive cyclopropanation of alkenes with CH2Cl2 as the methylene source. The use of mild terminal reductants (Zn or Et2Zn) confers significant functional‐group tolerance, and the catalyst accommodates structurally and electronically diverse alkenes. Mononickel catalysts bearing related N chelates afford comparatively
Site-Selective Catalytic Deaminative Alkylation of Unactivated Olefins
作者:Shang-Zheng Sun、Ciro Romano、Ruben Martin
DOI:10.1021/jacs.9b07489
日期:2019.10.16
A catalytic deaminative alkylation of unactivatedolefins is described. The protocol is characterized by its mild conditions, wide scope - including the use of ethylene as substrate -, and exquisite site-selectivity pattern for both a-olefins and internal olefins, thus unlocking a new catalytic platform to forge sp3-sp3 linkages, even in the context of late-stage functionalization.
new synthetic methodology for preparing cyclopropanes is presented. The reaction involves a cooperative zirconium- and Lewis acid-mediated deoxygenative coupling of carbonyl compounds with a Grignard reagent. In this way, various cyclopropanes are obtained in moderate to excellent yields, directly from saturated, unsaturated, and aromatic aldehydes and ketones. This reaction tolerates the presence of
Site-Selective Ni-Catalyzed Reductive Coupling of α-Haloboranes with Unactivated Olefins
作者:Shang-Zheng Sun、Marino Börjesson、Raul Martin-Montero、Ruben Martin
DOI:10.1021/jacs.8b09425
日期:2018.10.10
A mild, chemo- and site-selective catalytic protocol that allows for incorporating an alkylboron fragment into unactivated olefins is described. The use of internal olefins enables C-C bond-formation at remote sp3 C-H sites, constituting a complementary and conceptually different approach to existing borylation techniques that are currently available at sp3 centers.
描述了一种温和的、化学和位点选择性催化协议,允许将烷基硼片段纳入未活化的烯烃。内烯烃的使用能够在远程 sp3 CH 位点形成 CC 键,这构成了对当前在 sp3 中心可用的现有硼酸化技术的补充和概念上不同的方法。
Chelation Assistance in the Activation of Csp3-S Bonds in Nickel-Catalyzed Cross-Coupling Reactions
An unprecedented chelation approach to activate C(sp)3-S bonds in nickel-catalyzed cross-coupling reactions is described. Our theme was based on the formation of a chelation complex which results in the enhancement of the reactivity of aliphatic carbon-sulfur bonds. When two dithioacetal functionalities are located in close proximity, selective olefination of one of these two dithioacetal groups can thus be achieved conveniently. Depending on the relative positions of the newly formed double bond and the remaining dithioacetal group, tandem olefination occurs to give the corresponding 1,5-bis-silyl-substituted pentadienes. Various neighboring heteroatom substituents (OR, OH, NR(2) as well as SR groups) can facilitate the olefination of a dithioacetal group. Poly(thioether) linkage afforded the corresponding degradation products via a B-sulfur elimination process. 1,3-Dimercapto- and 1,3-dithiolatopropanes furnish the cyclopropane formation under nickel-catalyzed reaction conditions. The reaction of a dihydrothiopyran with MeMgI in the presence of the nickel catalyst proceeds via a sulfur-coordinated ir-allyl complex, which can further activate the CS bond to give vinylcyclopropane.