400-59-9Relevant articles and documents
Efficient method for selective introduction of substituents as C(5) of isoleucine and other α-amino acids
Reddy, Leleti Rajender,Reddy, B. V. Subba,Corey
, p. 2819 - 2821 (2006)
A useful process for the position-selective remote bromination of N-trifluoroacetyl-α-amino esters is illustrated for the isoleucine case. The 5-bromoisoleucine derivative shown above can be used for the synthesis of many modified amino acids, as described herein.
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
Activation energies of aminolysis of aliphatic esters in aprotic media
Tuulmets, Ants,Talvik, Agu-Tonis
, p. 111 - 119 (2007/10/03)
Activation enthalpies and entropies for the third-order aminolysis reaction of n-butyl formate, n-butyl-trichloroacetate and sec-butyl trifluoroacetate were determined in solvents of various polarity and π-basicity. The importance of the steric requirements of the reagents together with high activation entropy values support the assumption of cyclic transition states for the reaction. Electrophilicity of the ester and the solvent properties predetermine the reaction mechanism in the range between the pathway through a zwitterionic intermediate for the formate and the nearly concerted reaction for the trichloroacetate. The negative activation energy of an aminolysis reaction should not necessarily be attributed to a good leaving group, but can be determined by the electrophilicity of the ester and the solvent effects.