Cyclization of C-phosphorylated (PIII) arylformamidines to 3H-1,3-benzazaphospholes

A synthesis of 3H-1,3-benzazaphospholes starting from C-phosphorylated P(III) arylformamidines has been developed. Electron-donating substituents were found to enhance markedly the rate of the cyclization, with substituents at the meta position having the greatest effect. A plausible mechanism of the cyclization was proposed based on DFT calculations.

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