Functionalization of peptides and proteins by Mukaiyama aldol reaction.

The scope of the catalyst-free water-based Mukaiyama aldol reaction was explored through its application to the site-selective functionalization of N-terminal aldehydes of peptides and proteins. Various functional groups were introduced under mild and environmentally friendly conditions, with the first demonstration of aldol C-C bond formation in protein labeling studies. The efficiency and speed achieved in protein labeling can be of special interest in chemical biology studies.