Unveiling the Phosphine-Mediated N-Transfer from Azide to Isocyanide en Route to Carbodiimides and 4-Imino-1,3,2-diazaphosphetidines

• Published in: Organic letters 2024-12
• Main Authors: Pastor, Aurelia, Lopez-Leonardo, Carmen, Cutillas-Font, Guillermo, Martinez-Cuezva, Alberto, Marin-Luna, Marta, Garcia-Lopez, Jose-Antonio, Saura-Llamas, Isabel, Alajarin, Mateo
• Format: Article
• Language: English
• ISSN: 1523-7052; 1523-7052
• DOI: 10.1021/acs.orglett.4c03902

Intramolecular reactions between isocyano and iminophosphorane functions yield species containing an embedded 1,3,2-diazaphosphetidine ring, as result of the [2 + 2] cycloaddition of the primary reactive product, the cyclic carbodiimide, with a second unit of reactant. DFT studies reveal a first rate-determining step entailing a [2 + 1] cycloaddition involving the isocyanide carbon atom and the P═N double bond, with the further intervention of a dipolar precursor of the intermediate carbodiimide. The 1,3,2-diazaphosphetidine ring of the final products is shown to be hydrolytically and thermally labile.Intramolecular reactions between isocyano and iminophosphorane functions yield species containing an embedded 1,3,2-diazaphosphetidine ring, as result of the [2 + 2] cycloaddition of the primary reactive product, the cyclic carbodiimide, with a second unit of reactant. DFT studies reveal a first rate-determining step entailing a [2 + 1] cycloaddition involving the isocyanide carbon atom and the P═N double bond, with the further intervention of a dipolar precursor of the intermediate carbodiimide. The 1,3,2-diazaphosphetidine ring of the final products is shown to be hydrolytically and thermally labile.