The reactions of (2-chloroethynyl)diphenylphosphine oxide with diethyl 2-aminomalonate and of dimethyl (2-chloroethynyl)phosphonate with 2-amino-N-1,N-3-di(p-tolyl)malonamide or 2-aminomalonamide proceed chemo- and regioselectively to yield the corresponding 2-(phosphorylmethylene)oxazoles, namely diphenyl-[(4-ethoxycarbonyl-5-ethoxyoxazol-2-yl)methyl]phosphine oxide, dimethyl {[5-(p-tolylamino)-4-(p-tolylcarbamoyl)oxazol-2-yl]methyl}phosphonate, and dimethyl [(5-amino-4-carbamoyloxazol-2-yl)methyl]phosphonate, respectively.