| abstract |
The present invention provides a process comprising substitution of an acceptor molecule comprising a group -XC(O)- wherein X is O, S or NR 8 , where R 8 is C 1-6 alkyl, C 6-12 aryl or hydrogen, with a nucleophile, wherein the acceptor molecule is cyclised such that the said nucleophilic substitution at -XC(O)- occurs without racemisation. This process has particular application for the production of a peptide by extension from the activated carboxy-terminus of an acyl amino acid residue without epimerisation. |