19179-12-5Relevant articles and documents
Chiral recognition of diketopiperazine cyclo(Pro-Gly) and propranolol using (-)-Epigallocatechin-3-O-gallate
Ishizu, Takashi,Tsutsumi, Hiroyuki,Yokoyama, Emi,Tanabe, Haruka,Yokoyama, Aoi
, p. 142 - 149 (2016)
In the 1H-NMR spectrum of a solution containing an equimolecular amount of cyclo(L-Pro-Gly), cyclo(D-Pro-Gly) and (-)-epigallocatechin-3-O-gallate (EGCg) in a D2O, a difference in the chemical shift of 1H-NMR signal for H7a, H7β8a of the Pro residue was observed. Judging from the crystal structures of the 2: 2 complexes of EGCg and cyclo(L-Pro-Gly), cyclo(D-Pro-Gly), the difference in the chemical shift resulted mainly from a magnetic anisotropic shielding effect by the ring current from the B ring of EGCg. Therefore, it was considered that chirality of cyclo(Pro-Gly) was recognized by EGCg in the D2O solution. Furthermore, in the 1H-NMR spectrum of a solution containing an equimolecular amount of racemic propranolol ((R)- and (S)-propranolols) and EGCg in D2O, the 1H-NMR signal for H2 of the naphthalene group was observed as two doublets, suggesting that the racemic propranolol formed diastereomers of complexes with EGCg; as a result, chirality of propranolol was recognized by EGCg in the D2O solution.
Bis(2-sulfanylethyl)amido peptides enable native chemical ligation at proline and minimize deletion side-product formation
Raibaut, Laurent,Seeberger, Phillip,Melnyk, Oleg
supporting information, p. 5516 - 5519 (2013/11/19)
Native chemical ligation of C-terminal peptidyl prolyl alkylthioesters with N-terminal cysteinyl peptides usually exhibits poor kinetic rates compared to other C-terminal amino acid residues. It is shown here that the reaction is accompanied by the formation of a deletion side product which is minimized by using a bis(2-sulfanylethyl)amido (SEA) thioester surrogate at a mildly acidic pH.
Direct acyl substitution of carboxylic acids: A chemoselective o- to N-acyl migration in the traceless staudinger ligation
Kosal, Andrew D.,Wilson, Erin E.,Ashfeld, Brandon L.
supporting information, p. 14444 - 14453,10 (2020/09/16)
A chlorophosphite-modified, Staudinger-like acylation of azides involving a highly chemoselective, direct nucleophilic acyl substitution of carboxylic acids is described. The reaction provides the corresponding amides with analytical purity in 32-97 % yield after a simple aqueous workup without the need for a pre-activation step. The use of chlorophosphites as dual carboxylic acid-azide activating agents enables the formation of acyl C-N bonds in the presence of a wide range of nucleophilic and electrophilic functional groups, including amines, alcohols, amides, aldehydes, and ketones. The coupling of carboxylic acids and azides for the formation of alkyl amides, sulfonyl amides, lactams, and dipeptides is described. Copyright