102036-11-3Relevant articles and documents
Photochemistry of dipeptides in aqueous solution
Hill, Roger R.,Coyle, John D.,Birch, David,Dawe, Edwin,Jeffs, Graham E.,Randall, David,Stec, Iwan,Stevenson, Tessa M.
, p. 1805 - 1817 (1991)
The photochemical lability of peptides is poorly understood, largely because of the lack of product data. In the present study, product analyses have been carried out following the photolyses in aqueous solution of selected glycyl dipeptides (Gly-Gly, DL-Ala-Gly, L-Val-Gly, L-Pro-Gly, L-Phe-Gly, and Gly-L-Phe), L-prolyl-L-phenylalanine, and L-phenylalanyl-L-proline. Efficient deamination and decarboxylation of aliphatic dipeptides generate thermal precursors of simple amides in a photoinduced electron-transfer process involving the peptide bond. An analogous pathway in the photodegradation of phenylalanyl peptides suffers competition from other types of reaction.
Highly Diastereo- and Enantioselective Michael Addition of Nitroalkanes to 2-Enoyl-Pyridine N-Oxides Catalyzed by Scandium(III)/Copper(II) Complexes
Li, Lijun,Zhang, Sheng,Hu, Yanbin,Li, Yanan,Li, Chong,Zha, Zhenggen,Wang, Zhiyong
supporting information, p. 12885 - 12888 (2015/09/07)
A C2-symmetric Schiff-base ligand, derived from tridentate-Schiff-base, was developed and successfully applied to the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. With this newly catalytic system, an unprecedented diastereoselectivity was obtained in the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. In addition, a switch in enantioselectivity was achieved by using this newly catalytic system and our previous catalyst. After a facile reduction, the optically active adduct was converted to a biologically active dihydro-2H-pyrrol 4a. Furthermore, a connection of two tridentate-Schiff-base subunits proved to be an effective strategy in ligand design. Complex chemistry! A C2-symmetric Schiff-base ligand, derived from tridentate-Schiff-base, was developed and successfully applied to the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides with unprecedented diastereoselectivity (see scheme).
The role of the amino acid-derived side chain in the preorganization of c2-symmetric pseudopeptides: Effect on sn2 macrocyclization reactions
Marti-Centelles, Vicente,Burguete, M.Isabel,Cativiela, Carlos,Luis, Santiago V.
, p. 559 - 570 (2014/04/03)
A family of pseudopeptidic macrocycles containing non-natural amino acids have been synthesized. The macrocyclization reaction has been studied experimentally and computationally, demonstrating the key role of both the amino acid side chain and the catalytic bromide anion. The bromide anion acts as an external template assisting the folding of the open-chain precursor in a proper conformation. Computations revealed that in the presence of the anion, the effect of the side chain on the energy barrier for the macrocyclization is very small. However, the effect on the conformational equilibria of the open-chain precursors is very important. Overall, the stabilization of those conformation(s) in which the two reactive ends of the open-chain intermediate are located at short distances from each other with the correct orientation is the critical parameter defining the success of the macrocyclization. The best yield was found for the compound containing cyclohexylalanine, for which the computationally-predicted most stable conformer in the presence of Br- has a proper preorganization for cyclization. The remarkable agreement obtained between experiments and theory reveals that the computational approach here considered can be of great utility for the prediction of the behavior of other related systems and for the design of appropriate synthetic routes to new macrocyclic compounds.
