Synthesis of 1,3-Diaminoisoquinoline Derivatives via N-Oxide Intermediates from o-Cyanobenzyl Cyanides.

1,3-Diaminoisoquinolines represent distinctive scaffolds that merge the isoquinoline core, prevalent in natural products and pharmaceuticals, with a 2,6-diaminopyridine-type hydrogen-bonding motif. Despite their attractive structural features, access to these frameworks remains limited by existing synthetic methods. Herein, we introduce a facile synthetic method for the preparation of 1,3-diaminoisoquinolines via cyclization of o-cyanobenzyl cyanides with hydroxylamine, followed by a one-pot reduction using B2pin2. This approach exhibits broad substrate tolerance and enables rapid, efficient access to diverse 1,3-diaminoisoquinoline derivatives.