Enantioselection in peptide bond formation.
Selectivity in abiotic condensations of amino acids remains controversial and stereochemically little explored. We find that competitive activated couplings of N-acyl derivatives of glycine, alanine, valine, proline and phenylalanine with binary, ternary and quaternary mixtures of amides and esters of the same group of amino acids show little selectivity among the reactants, except with respect to configuration, where a consistent and significant preference for heterochiral outcomes, mostly > 80%, is observed. One possible explanation of this selectivity predicts a predisposition to homochiral coupling under conditions that would require the two carboxyl functions to be co-facial in the activated complex.
Hill
Roger R
RR
Department of Chemistry, Open University, Milton Keynes, UK MK7 6AA. r.r.hill@open.ac.uk
Birch
David
D
Jeffs
Graham E
GE
North
Michael
M
D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D010455:Peptides / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000596:Amino Acids; D010455:Peptides