| abstract |
A process for the preparation of a compound of formula (1)comprises reacting compounds of formulae (2) and (3)in the presence of an enzyme, wherein A is a thiol-protecting group, B, C and D are each the same or different organic groups of up to 30 C atoms, optionally functionalized at any position, provided that neither a primary amine nor a primary amide is present, and X is a group that can be displaced by NH2. |