Insertion of diazocarbonyl-derived metallocarbenes into X-H bonds (X= H, C, Si, N, O, S, P, Se) has
proven to be a very important method for the construction of C-X bonds in organic chemistry. This mini-review
provides a brief historical background, mechanistic aspects and a summary of recent breakthroughs in the area of
enantioselective metal-catalyzed N-H and O-H insertion reactions.