Directed carbonylative (3+1+2) cycloadditions of amino-substituted cyclopropanes and alkynes: reaction development and increased efficiencies using a cationic rhodium system
摘要:
Urea-directed carbonylative insertion of Rh(I)-catalysts into one of the two proximal C-C bonds of aminocyclopropanes generates rhodacyclopentanone intermediates. These are trapped by N-tethered alkynes to provide a (3+1+2) cycloaddition protocol that accesses N-heterobicyclic enones. Stoichiometric studies on a series of model rhodacyclopentanone complexes outline key structural features and provide a rationale for the efficacy of urea directing groups. A comprehensive evaluation of cycloaddition scope and a 'second generation' cationic Rh(I)-system, which provides enhanced yields and reaction rates for challenging substrates, are presented. (C) 2015 The Authors. Published by Elsevier Ltd.
Directing Group Enhanced Carbonylative Ring Expansions of Amino-Substituted Cyclopropanes: Rhodium-Catalyzed Multicomponent Synthesis of N-Heterobicyclic Enones
摘要:
Aminocyclopropanes equipped with suitable N-directing groups undergo efficient and regioselective Rh-catalyzed carbonylative C-C bond activation. Trapping of the resultant metallacycles with tethered alkynes provides an atom-economic entry to diverse N-heterobicyclic enones. These studies provide a blueprint for myriad N-heterocyclic methodologies.
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‐Directing‐Group Strategy Unlocks Enantioselective (3+1+2) Carbonylative Cycloadditions of Aminocyclopropanes
作者:Olga O. Sokolova、John F. Bower
DOI:10.1002/anie.202205007
日期:2022.8.8
An endo-directing group strategy enables enantioselective (3+1+2) cycloadditions that are triggered by carbonylative C−C bond activation of cyclopropanes. These processes are rare examples of cycloadditions where C−C bond oxidative addition is enantiodetermining.