33294-54-1Relevant articles and documents
Induced axial chirality in the biphenyl core of the proatropoisomeric, Cα-tetrasubstituted α-amino acid residue Bip in peptides
Mazaleyrat, Jean-Paul,Wright, Karen,Gaucher, Anne,Toulemonde, Nathalie,Dutot, Laurence,Wakselman, Michel,Broxterman, Quirinus B.,Kaptein, Bernard,Oancea, Simona,Peggion, Cristina,Crisma, Marco,Formaggio, Fernando,Toniolo, Claudio
, p. 6921 - 6929 (2005)
An induced axial chirality in the biphenyl core of the 2′,1′:1,2;1″,2″:3,4-dibenzcyclohepta-1, 3-diene-6-amino-6-carboxylic acid (Bip) residue, a conformationally labile, atropoisomeric, Cα-tetrasubstituted α-amino acid, was observed by CD and 1H NMR spectroscopic techniques in the linear dipeptides Boc-Bip-Xaa*-OMe where Boc = tert-butoxycarbonyl, OMe = methoxy, and Xaa* = D- and/or L-Ala, -Val, -Leu, -Phe, -(αMe)Val and -(αMe)Leu. Chiral induction was significantly lower in the isomeric dipeptides Boc-Xaa*-Bip-OMe, with the Xaa* residue located at the N-terminus of Bip, as well as in the cyclic dipeptide cyclo-[Bip-L-Ala]. The results obtained in solution were confirmed by X-ray diffraction analysis of a crystalline sample of Boc-(R)-Bip-D-Ala-OMe.
Synthesis of 6- and 7-membered cyclic enaminones: Scope and mechanism
Niphakis, Micah J.,Turunen, Brandon J.,Georg, Gunda I.
supporting information; experimental part, p. 6793 - 6805 (2010/12/20)
Six- and seven-membered cyclic enaminones can be prepared using common, environmentally benign reagents. Amino acids are used as synthetic precursors allowing diversification and the incorporation of chirality. The key reaction in this multistep process involves deprotection of Boc-amino ynones and subsequent treatment with methanolic K2CO3 to induce cyclization. A β-amino elimination side reaction was identified in a few labile substrates that led to either loss of stereochemical purity or degradation. This process can be mitigated in specific cases using mild deprotection conditions. NMR and deuterium-labeling experiments provided valuable insight into the workings and limitations of this reaction. Although disguised as a 6-endo-dig cyclization, the reagents employed in the transformation play a direct role in bond-making and bond-breaking, thus changing the mode of addition to a 6-endo-trig cyclization. This method can be used to construct an array of monocyclic and bicyclic scaffolds, many of which are found in well-known natural products (e.g., indolizidine, quinolizidine, and Stemona alkaloids).
Aziridinyl peptides as inhibitors of cysteine proteases: Effect of a free carboxylic acid function on inhibition
Schirmeister,Peric
, p. 1281 - 1291 (2007/10/03)
Peptides containing aziridine-2,3-dicarboxylate (Azi) as electrophilic building block are evaluated as inhibitors of the cysteine proteases papain, cathepsin B, cathepsin L and clostripain. The influence of a free carboxylic acid as functional group at di
