Synthesis of α-Alkoxyacrylonitriles Using Substituted Diethyl Cyanomethylphosphonates

The synthesis of the thiophenoxy, methoxy, and tert-butoxy derivatives of diethyl cyanomethylphosphonates (EtO)₂POCH(Z)CN 3 involved either the phenylsulfenylation of the anion of diethyl cyanomethylphosphonate (4) to afford 3a (Z = SPh), the photolysis of the diazo derivative of 4 in methanol to afford 3b (Z = OMe), or, preferably, the Arbusov reaction of methoxy- or tert-butoxybromoacetonitrile with triethyl phosphite to afford 3b (Z = OMe) or 3c (Z = O-t-Bu), respectively. The latter two phosphonate reagents 3b and 3c serve in the Horner-Emmons modification of the Wittig reaction to provide α-alkoxyacrylonitriles RR′C=C(OR″)CN 1 from carbonyl compounds RR′C=O in excellent yield.