Polynuclear lanthanide–diketonato clusters for the catalytic hydroboration of carboxamides and esters

Abstract

Catalytic reduction of carboxamides into their corresponding amines is an attractive but extremely challenging transformation, which often meets with limited success; the valuable amine products drive ongoing research in this area. Here we show the direct deoxygenation of carboxamides using earth-abundant lanthanum catalysts in the presence of HBpin, presenting good to excellent yields with broad substrate scope and functional group/heteroatom tolerance. Moreover, this method is also effective in catalysing the hydroboration of esters. Finally, selective cleavage of the amide group bonds (C–N versus C–O) could be achieved based on the nature of the nitrogen substituents. Amide reduction via hydroboration is challenging, and catalysts often exhibit limited substrate scope. Here the authors report synthesis of a lanthanum cluster as a catalyst for the hydroboration of esters and amides, capable of reducing a wide range of primary, secondary and tertiary amides to amines.