Controlled reduction of isocyanates to formamides using monomeric magnesium

Abstract

This work describes a transition metal-free methodology involving an efficient and controlled reduction of isocyanates to only formamide derivatives using pinacolborane (HBpin) as the hydrogenating agent and a bis(phosphino)carbazole ligand...

Lanthanide Mimicking by Magnesium for Oxazolidinone Synthesis

“…We recently published a report on a compound called bis(phosphino)carbazolide-magnesium methyl, which we used as a catalyst for the hydroboration of alkenes, alkynes, terpenes, and the controlled reduction of isocyanates to formamides using HBpin. [25,27] However, when we tried to use this compound for the cyclization of propargyl alcohol and isocyanate, we didn't obtain the expected oxazolidinone derivatives. Therefore, we decided to make slight modifications to the ligand.…”

“…In this regard, Pucheault and coworkers developed a tandem dehydrogennation/dehydrocoupling strategy for the construction of alkynylboranes using a magnesium catalyst. Building upon our recent achievements in employing alkaline earth metal compounds for hydrofunctionalization reactions, [23][24][25][26][27][28] we are intrigued by the possibility of using a magnesium compound for intermolecular reactions between isocyanates and propargylic alcohols, and thus providing an efficient pathway for synthesizing oxazolidinone derivatives. A further impetus comes from the works of Hill and coworkers showcasing tandem reactions of alkynes and heterocumulenes to form imidazolidine-2,4-diones using alkaline earth metal amides.…”

Magnesium halide-catalyzed hydroboration of isocyanates and ketones

“…of HBpin giving exclusively N -boryl formamides. 38 To our surprise, except for the above sole magnesium example to obtain complete hydroboration products, there is no other report on Mg-catalyzed deoxygenated hydroboration of isocyanates furnishing N -boryl methyl amine products.…”

Magnesium(ii) complexes supported by indole- and pyrrole-containing Schiff-base ligands: syntheses, structures, and applications as precatalysts in the hydroboration of nitriles and alkynes

“…Earth-abundant main group-metal complexes offer nontoxic, inexpensive and sustainable alternatives to precious transitionmetal catalysts in various synthetic transformations, especially in the hydroboration of carbon-heteroatom and carbon-carbon multiple bonds. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] These hydroboration reactions represent a series of atom-economic processes for the preparation of boroncontaining compounds. In these compounds, the boroncontaining groups could serve as functional handles for synthesizing new C-C bonds or for transforming boron-containing groups into halogen, alcohol, amine and amide functionalities.…”