Al/P Frustrated Lewis pair catalyzed metathesis of carbon-heteroatom double bonds between aldehydes and isocyanates

Imines are fundamental building blocks in organic synthesis, and the development of efficient methods for their preparation remains an important challenge. Metathesis between the carbon–oxygen double bond (C=O) of carbonyl compounds and the carbon–nitrogen double bond (C=N) of isocyanates offers a promising route to imines. Herein, we report an Al/P FLP-catalyzed C=O/C=N metathesis that enables the synthesis of imines from aldehydes and isocyanates. Mechanistic investigations revealed that the unique catalytic activity of an Al/P FLP bearing two PCy2 groups arises from the presence of a non-coordinating PCy2 group, which facilitates catalyst regeneration from a resting state through reversible dissociation of the aldehyde adduct.