1: TEA / tetrahydrofuran / 0.5 h / 20 °C 2: tetrahydrofuran; dimethylformamide / 16 h / 20 °C View Scheme

TEA; phosphorochloridic acid diphenyl ester 1.) THF, 55 deg C, 2 h, 2.) THF, DMF, 20 deg C, 2 h; Yield given. Multistep reaction;