O-Substituted hydroxyl amine reagents: an overview of recent synthetic advances

Reagents derived from hydroxylamines such as 2,4-dinitrophenylhydroxylamine (DPH), O-(diphenylphosphinyl)hydroxylamine (DPPH), hydroxylamine-O-sulfonic acid (HOSA) and other related reagents in which oxygen is substituted with good leaving groups recently showed remarkable potential as electrophilic aminating agents and as a source of the amino group. They facilitate stereo- and regioselective C–N, N–N, O–N, and S–N bond-formation reactions and intra-molecular cyclizations without the requirement of expensive metal catalysts. In this review we have discussed the important transformations achieved with these reagents.