Magnesium catalyzed hydroamination of carbodiimides and hydroboration of cyanamides

A β-diketiminate magnesium hydride complex, Mg-1 [{LMgH}₂; L = ^DepNacnac = (DepNCMe)₂CH; Dep = 2,6-Et₂-C₆H₃], catalyzes the hydroamination of carbodiimides with primary aryl amines and the hydroboration of cyanamides with HBpin. The reactions proceed efficiently under mild conditions, affording a range of guanidines, <i>N</i>-borylformamidines, and <i>N</i>,<i>N</i>-bis-boryldiamines in high yields. Detailed stoichiometric experiments and the successful isolation of active catalysts/key intermediates, <i>i.e.</i>, magnesium anilide [{LMg-NH-C₆H₄-4-Me}₂] (Mg-2), magnesium amidinate [{LMg-NCH-N(Et₂)}₂] (Mg-3), and magnesium guanidinate [LMg(NⁱPr)(N-<i>p</i>-tolyl)C-NH-ⁱPr] (Int-A2) complexes, provided insights into the reaction mechanisms, enabling the elucidation of plausible catalytic cycles. These results highlight the potential of Earth-abundant magnesium-based catalysts for synthesizing valuable nitrogen-containing compounds.