(Diazomethyl)dimethylphosphine Oxide - A Diazoalkane Reagent for [3+2] Cycloadditions.

A safe and efficient method for the in-situ preparation of (diazomethyl)dimethylphosphine oxide - a hereto unexplored diazoalkane reagent - is developed. The method is based on the diazotization of the corresponding P(O)Me-substituted amine (readily available in multigram quantities) in non-aqueous media. The protocol provides the target product as ca.