Abstract
The formation of amide bonds represents one of the most fundamental processes in organic synthesis. Transition-metal-catalyzed activation of acyclic twisted amides has emerged as an increasingly powerful platform in synthesis. Herein, we report the transamidation of N-activated twisted amides by selective N–C(O) cleavage mediated by air- and moisture-stable half-sandwich Ni(II)–NHC (NHC = N-heterocyclic carbenes) complexes. We demonstrate that the readily available cyclopentadienyl complex, [CpNi(IPr)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), promotes highly selective transamidation of the N–C(O) bond in twisted N-Boc amides with non-nucleophilic anilines. The reaction provides access to secondary anilides via the non-conventional amide bond-forming pathway. Furthermore, the amidation of activated phenolic and unactivated methyl esters mediated by [CpNi(IPr)Cl] is reported. This study sets the stage for the broad utilization of well-defined, air- and moisture-stable Ni(II)–NHC complexes in catalytic amide bond-forming protocols by unconventional C(acyl)–N and C(acyl)–O bond cleavage reactions.
Highlights
The amide bond represents one of the most fundamental and important functional groups in organic synthesis [1,2,3]
In continuation of our studies on activation of amide bonds and organometallic catalysis, in this Special Issue of Editorial Board members of the Organometallic Section of Molecules, we report transamidation of N-activated amides by selective N–C(O) cleavage mediated by air- and moisture-stable half-sandwich Ni(II)–NHC
We have reported on the transamidation reactions of N-activated amides by selective N–C(O) cleavage mediated by the well-defined, air- and moisture-stable halfsandwich [CpNi(IPr)Cl] complex
Summary
The amide bond represents one of the most fundamental and important functional groups in organic synthesis [1,2,3]. Transamidation reactions of twisted amide N–C(O) bonds have been achieved using well-defined Pd(II)–NHC catalysts as well as by using airsensitive Ni(cod) in combination with NHC ligands [16,17,18,19,20,21]. These reactions provide a variety of novel methods for the synthesis of ubiquitous amide bonds and have been extended to catalytic amidation reactions of activated phenolic and unactivated methyl esters by O–C(O) cleavage [22,23,24,25].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
