An un-forgotten classic: the nitro-Mannich reaction between nitrones and silyl nitronates catalysed by B(C 6 F 5 ) 3 .

Herein we report the B(C 6 F 5 ) 3 -catalysed nitro-Mannich reaction between nitrones and silyl nitronates, affording silyl-protected α-nitro hydroxylamines with yields up to 99% and diastereoselectivities up to 99 : 1. Crucially, the obtained products can be converted into 1,2-diamines under simple reductive conditions. This work provides a new orthogonal method to the existing routes for the instalment of a nitro moiety under Lewis acid catalysed conditions, and expands the state-of-the-art substrate scope with respect to the silyl nitronates.