The catalytic activity of actinide-based catalysts is presented herein for the hydroboration and deoxygenation of isocyanates with pinacolborane (HBpin). A modified class of ligand systems possessing a five-membered ring core constructing the N-heterocyclic iminato moiety is introduced. All actinide complexes showed very good catalytic activities under mild conditions, with low catalyst loadings achieving almost quantitative yields. A wide number of isocyanates were studied including aliphatic isocyanates, aromatic isocyanates, and diisocyanates yielding to the corresponding borylated N-methyl amines and the borylated formamides, which are easily hydrolyzed toward the free amines and formamides. These organoactinide catalysts exhibited a great functional group tolerance toward methoxy, amido, and halides. The reaction selectivity was thoroughly investigated and exhibited a very good selectivity toward the isocyanate functionality having double or triple unsaturated C-C bonds. Kinetic studies were performed in order to establish the rate order dependency on the concentrations of the organoactinide complex, HBpin, and isocyanate. A proposed mechanism is presented based on experiments affording a more comprehensive understanding of the experimental activity trends and reinforced by the stoichiometric reaction studies, thermodynamic measurements, deuterium-labeling experiments, and theoretical DFT calculations.

Against All Odds, Uranium and Thorium Iminato Complexes Enable the Cleavage of C═O Bonds in Isocyanates

Ritacco I.;Caporaso L.
;
2023-01-01

Abstract

The catalytic activity of actinide-based catalysts is presented herein for the hydroboration and deoxygenation of isocyanates with pinacolborane (HBpin). A modified class of ligand systems possessing a five-membered ring core constructing the N-heterocyclic iminato moiety is introduced. All actinide complexes showed very good catalytic activities under mild conditions, with low catalyst loadings achieving almost quantitative yields. A wide number of isocyanates were studied including aliphatic isocyanates, aromatic isocyanates, and diisocyanates yielding to the corresponding borylated N-methyl amines and the borylated formamides, which are easily hydrolyzed toward the free amines and formamides. These organoactinide catalysts exhibited a great functional group tolerance toward methoxy, amido, and halides. The reaction selectivity was thoroughly investigated and exhibited a very good selectivity toward the isocyanate functionality having double or triple unsaturated C-C bonds. Kinetic studies were performed in order to establish the rate order dependency on the concentrations of the organoactinide complex, HBpin, and isocyanate. A proposed mechanism is presented based on experiments affording a more comprehensive understanding of the experimental activity trends and reinforced by the stoichiometric reaction studies, thermodynamic measurements, deuterium-labeling experiments, and theoretical DFT calculations.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4846071
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