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.
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.
Enantioselective Reductive Homocoupling of Allylic Acetates Enabled by Dual Photoredox/Palladium Catalysis: Access to <i>C</i><sub>2</sub>-Symmetrical 1,5-Dienes
emerged as powerful protocols to construct C–C bonds. However, the development of enantioselective C(sp3)–C(sp3) reductive coupling remains challenging. Herein, we report a highly regio-, diastereo-, and enantioselective reductive homocoupling of allylic acetates through cooperative palladium and photoredox catalysis using diisopropylethylamine or Hantzsch ester as a homogeneous organic reductant.
Regio- and Enantioselective Decarboxylative Allylic Benzylation Enabled by Dual Palladium/Photoredox Catalysis
作者:Changhua Song、Hong-Hao Zhang、Shouyun Yu
DOI:10.1021/acscatal.1c05461
日期:2022.1.21
A decarboxylative allylic benzylation cocatalyzed by Pd/photoredox in a regio- and enantioselective manner has been achieved. Readily available aryl acetic acids are used as benzylic nucleophile equivalents without preactivation. This mild and atom-economical protocol expands the scope of coupling partners of allylic electrophiles. Vinyl epoxides could also go through this transformation smoothly,
Enantioselective Allylic Alkylation with 4-Alkyl-1,4-dihydro-pyridines Enabled by Photoredox/Palladium Cocatalysis
作者:Hong-Hao Zhang、Jia-Jia Zhao、Shouyun Yu
DOI:10.1021/jacs.8b10766
日期:2018.12.12
alkylation has been achieved enabled by the merger of photoredox and palladiumcatalysis. In this dual catalytic process, alkyl radicals generated from 4-alkyl-1,4-dihydropyridines act as the coupling partners of the π-allyl palladium complexes. The generality of this method has been illustrated through the reaction of a variety of allylesters with 4-alkyl-1,4-dihydropyridines. This mechanistically novel
A nickel catalyzed asymmetric allylation of secondary phosphineoxides (SPO) for the synthesis of tertiary phosphineoxides (TPO) was realized with high enantioselectivity. The dynamic kinetic resolution of SPO was accomplished in the presence of nickel complex. By elucidating the absolute configurations of the reacted SPO starting material and the TPO product, we confirmed that the allylation reaction
Electrochemical-Promoted Nickel-Catalyzed Reductive Allylation of Aryl Halides
作者:Wangzhe Chen、Shengyang Ni、Yi Wang、Yi Pan
DOI:10.1021/acs.orglett.2c01247
日期:2022.5.27
with conventional reductive coupling, reductive coupling under electrochemical conditions without external reductants is greener, milder, and more efficient and is of increasing interest to organic chemists. In this work, we report the sacrificial anode, nickel-catalyzed electrochemical allylation reaction of aryl and alkylhalides. The reaction can be applied to a range of allylation reagents such as