Thiazolidine chemistry revisited: a fast, efficient and stable click-type reaction at physiological pH.

We describe the fast reaction kinetics between 1,2-aminothiols and aldehydes. Under physiological conditions such a click-type reaction afforded a thiazolidine product that remains stable and did not require any catalyst. This type of bioorthogonal reaction offers enormous potential for the coupling of biomolecules in an efficient and biocompatible manner.