Synthesis of E / Z N ‐(1‐Chlorovinyl)formamide Using Vilsmeier–Haack Reaction

Synthesis of a variety of novel Z/E N-(1-chlorovinyl)formamides through Vilsmeier-Haack reaction starting from 2-phenoxyethanamides with POCl3/DMF has been accomplished. The reactions introduced chlorine atom to the C-alpha-position and phenoxy substitutions to the C-beta-position of N-vinylformamides, and the Z/E isomers of N-(1-chlorovinyl)formamide were isolated and characterized. In most cases, Z/E N-(1-chlorovinyl)formamides were both obtained; however, for the steric hindrance reason, the reaction starting from cyclohexylamine afforded sole Z isomer of N-(1-chloro-2-(2,4-dichlorophenoxy)vinyl)-N-cyclohexylformamide as the highly regioselective product.