Regiocontrol and Stereoselectivity in Tungsten-Bipyridine Catalysed Allylic Alkylation
摘要:
Tungsten-bipyridine complexes, generated in situ, catalyse the allylic alkylation of isocinnamyl methyl carbonate by dimethyl sodiomalonate [NaCH(CO2CH3)(2)] with complete syn-stereoselectivity. When para substituted aryl-allyl methyl carbonates are employed, the regioselectivity correlates with Swain-Lupton parameters. Cross-over experiments demonstrate that the reactions do not procede via the conventional [M(0)] --> [M(II) allyl](+) --> [M(0) allyl-Nu] catalytic cycle.
Co‐catalyzedallylic substitution reactions have received little attention, arguably because of the lack of any known advantage of Co catalysis over either Rh or Ir catalysis. Described here is a general and regioselective Co‐catalyzedallylicalkylation using an in situ catalyst activation by organophotoredox catalysis. This noble‐metal‐free catalytic system exhibits unprecedentedly high reactivities
作者:Can-Can Bao、Dong-Song Zheng、Xiao Zhang、Shu-Li You
DOI:10.1021/acs.organomet.8b00762
日期:2018.12.24
N-Heterocyclic carbenes (NHCs) were found to be suitable ligands in Ir-catalyzed intermolecular allylic alkylation reaction. In the presence of a catalyst derived from [Ir(dncot)Cl]2 (dncot = dinaphthocyclooctatetraene) and triazolium salt L7, the alkylation products from the reaction of aryl allyl carbonates with sodium dialkyl malonates could be obtained in 85–99% yields favoring the formation of
发现N-杂环卡宾(NHC)是Ir催化的分子间烯丙基烷基化反应中的合适配体。在[Ir(dncot)Cl] 2(dncot =二萘环辛酸酯四烯)和三唑鎓盐L7衍生的催化剂存在下,芳基烯丙基碳酸酯与二烷基丙二酸钠的反应可得到烷基化产物,收率高达85-99%,形成支链产物(90/10→> 99/1 b / l)。此外,手性二氢异喹啉型NHC(DHIQ-NHC)(L8)已成功应用于Ir催化的不对称烯丙基烷基化反应中。对于广泛的底物,获得了优异的对映选择性和中等的区域选择性。
A Bis(Triazolecarboxamido) Ligand for Enantio- and Regioselective Molybdenum-Catalyzed Asymmetric Allylic Alkylation Reactions
作者:Erhan Ozkal、Miquel A. Pericàs
DOI:10.1002/adsc.201300967
日期:2014.3.10
A modular, enantiomerically pure bis(1H‐1,2,3‐triazole‐4‐carboxamide) has been assembled from N,N′‐[(1R,2R)‐cyclohexane‐1,2‐diyl]dipropiolamide through a copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) reaction and evaluated as a ligand in the molybdenum‐catalyzed asymmetricallylicalkylation (MoAAA) reaction, very high regio‐ and enantioselectivities being recorded.
methodology for the allylic C–H alkylation of unactivated alkenes with diazocompounds is demonstrated. The developed protocol is able to bypass the possibility of the cyclopropanation of an alkene upon its reaction with the acceptor–acceptor diazocompounds. The protocol is highly accomplished due to its compatibility with various unactivated alkenes functionalized with different sensitive functional groups