DBU-promoted cascade phosphorylation/cyclization for the synthesis of phosphorylated 3-aminoindoles

A novel strategy of cascade phosphorylation cyclization of 2-isocyanobenzonitrile with phosphine oxide via a DBU-promoted process has been developed. A series of phosphorylated 3-aminoindoles were constructed by forming C-C, C-P and N-P bonds and an amino group in one pot. A plausible reaction mechanism has been proposed based on step-by-step control experiments and ³¹P NMR analysis.