Potassium dihydrogen phosphate: an inexpensive reagent for the solvent-free, one-pot synthesis of [alpha]-aminophosphonates

An efficient procedure is described for the synthesis of α-aminophosphonates in the presence of catalytic amount of potassium dihydrogen phosphate (5 mol%) under solvent-free condition at room temperature. Triethyl phosphite reacts with imines (generated in situ from an aldehyde and an amine) to give corresponding coupled products in excellent yields. The present methodology presents several advantages, such as elevated yield, short reaction time, and easy work-up.