3389-53-5Relevant articles and documents
A CO2-Catalyzed Transamidation Reaction
Yang, Yang,Liu, Jian,Kamounah, Fadhil S.,Ciancaleoni, Gianluca,Lee, Ji-Woong
, p. 16867 - 16881 (2021/11/18)
Transamidation reactions are often mediated by reactive substrates in the presence of overstoichiometric activating reagents and/or transition metal catalysts. Here we report the use of CO2as a traceless catalyst: in the presence of catalytic amounts of CO2, transamidation reactions were accelerated with primary, secondary, and tertiary amide donors. Various amine nucleophiles including amino acid derivatives were tolerated, showcasing the utility of transamidation in peptide modification and polymer degradation (e.g., Nylon-6,6). In particular,N,O-dimethylhydroxyl amides (Weinreb amides) displayed a distinct reactivity in the CO2-catalyzed transamidation versus a N2atmosphere. Comparative Hammett studies and kinetic analysis were conducted to elucidate the catalytic activation mechanism of molecular CO2, which was supported by DFT calculations. We attributed the positive effect of CO2in the transamidation reaction to the stabilization of tetrahedral intermediates by covalent binding to the electrophilic CO2
Synthesis of Novel Heterocycles by Amide Activation and Umpolung Cyclization
Maulide, Nuno,Riomet, Margaux,Roller, Alexander,Zhang, Haoqi
supporting information, (2020/03/24)
Herein, we report a metal-free synthesis of cyclic amidines, oxazines, and an oxazinone under mild conditions by electrophilic amide activation. This strategy features an unusual Umpolung cyclization mode and enables the smooth union of α-aryl amides and diverse alkylazides, effectively rerouting our previously reported α-amination transform.
Synthesis of secondary and tertiary amides without coupling agents from amines and potassium acyltrifluoroborates (KATs)
Bode, Jeffrey W.,Ryan, Sarah J.,Schuhmacher, Anne,Shiro, Tomoya
, p. 7609 - 7614 (2020/08/14)
Although highly effective for most amide syntheses, the activation of carboxylic acids requires the use of problematic coupling reagents and is often poorly suited for challenging cases such as N-methyl amino acids. As an alternative to both secondary and tertiary amides, we report their convenient synthesis by the rapid oxidation of trifluoroborate iminiums (TIMs). TIMs are easily prepared by acid-promoted condensation of potassium acyltrifluoroborates (KATs) and amines and are cleanly and rapidly oxidized to amides with hydrogen peroxide. The overall transformation can be conducted either as a one-pot procedure or via isolation of the TIM. The unique nature of the neutral, zwitterionic TIMs makes possible the preparation of tertiary amides via an iminium species that would not be accessible from other carbonyl derivatives and can be conducted in the presence of unprotected functional groups including acids, alcohols and thioethers. In preliminary studies, this approach was applied to the late-stage modifications of long peptides and the iterative synthesis of short, N-methylated peptides without the need for coupling agents.
