The invention relates to a process for the conjugation of a molecule containing a thiol or amino group to a polymer, which comprises reacting said molecule with a compound of the general formula: €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ X-[Q-W-(CH=CH) n -CH=CH 2 ] m €ƒ€ƒ€ƒ€ƒ€ƒ(V) in which X represents a polymer； Q represents a linking group； W represents a keto group or an ester group -O-CO-； n represents 0 or an integer of from 1 to 4； and m represent an integer of from 1 to 8. The invention also relates to a compound of the general formula €ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ X-[NH-CO-Ar-W-(CH=CH) n -CH=CH 2 ] m €ƒ€ƒ€ƒ€ƒ€ƒ(Va) in which X, W, n and m have the meanings given above； and Ar represents an unsubstituted or substituted aryl group.
