Synthesis of α, β-unsaturated γ-amino esters with unprecedented high (E)-stereoselectivity and their conformational analysis in peptides
作者:Sachitanand M. Mali、Anupam Bandyopadhyay、Sandip V. Jadhav、Mothukuri Ganesh Kumar、Hosahudya N. Gopi
DOI:10.1039/c1ob05732d
日期:——
Mild, efficient and racemization-free synthesis of N-protected α, β-unsaturated γ-amino esters with unprecedented high E- stereoselectivity is described. This method is found to be compatible with Boc-, Fmoc- and other side chain protecting groups. The crystal conformations of the vinylogous γ-amino esters in monomers and in homo- and mixed dipeptides are studied. Further, the vinylogous homo-dipeptide showed a β-sheet conformation, while mixed α- and α,β-unsaturated γ-hybrid dipeptide adapted an irregular structure in single crystals.
Synthesis of Enantiomerically Pure 3-Substituted Piperazine-2-acetic Acid Esters as Intermediates for Library Production
作者:Shiva Krishna Reddy Guduru、Srinivas Chamakuri、Idris O. Raji、Kevin R. MacKenzie、Conrad Santini、Damian W. Young
DOI:10.1021/acs.joc.8b01708
日期:2018.10.5
substitutions, leaving the four carbon atoms underutilized. Using an efficient six-step synthesis, chiral amino acids were transformed into 3-substituted piperazine-2-acetic acid esters as diastereomeric mixtures whose cis and trans products (dr 0.56 → 2.2:1, respectively) could be chromatographically separated. From five amino acids (both antipodes) was obtained a complete matrix of 20 monoprotected chiral 2