Direct 1,1-Bisphosphonation of Isocyanides: Atom- and Step-Economical Access to Bisphosphinoylaminomethanes

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.

Silver-catalyzed P-centered anion nucleophilic addition to isocyanide: access to 2-phosphinoyl indoles/indol-3-ols

A silver-catalyzed chemoselective cascade nucleophilic addition of a P-centered anion to isocyanides and cyclization reaction was developed for the efficient and practical synthesis of a wide range of 2-phosphinoyl indole and indol-3-ol derivatives. Unlike the well-documented synthesis of phosphorus-functionalized heterocycles via a P-centered radical, an anionic reactivity profile of phosphine oxides is most likely involved in this domino transformation.

One-Pot Synthesis of α-Amino Bisphosphonates from Nitriles via Tf2O/HC(OR)3-Mediated Interrupted Ritter-Type Reaction

A versatile synthesis of α-amino bisphosphonates has been achieved through one-pot interrupted Ritter-type reaction under mild conditions. The reactive Ritter intermediate nitrilium is in situ generated by treatment of nitrile with readily accessible Tf₂O/HC(OR¹)₃, which is trapped by phosphite ester to deliver the desired product. This protocol is efficient, scalable, and well compatible with a broad scope of substrates. In addition, plentiful characteristic J_P-C couplings including unusual five-bond long-range ⁵J_P-C and ³J_P-C across quaternary carbon and hetero (N) atoms were observed in ¹³C NMR spectra.