Novel efficient synthesis of 1-ethoxyvinyl esters using ruthenium catalysts and their use in acylation of amines and alcohols: synthesis of hydrophilic 3′-N-acylated oxaunomycin derivatives

A novel and efficient synthesis of 1-ethoxyvinyl esters 3a–i from carboxylic acids 4a–i and ethoxyacetylene 5 by using a catalytic amount of ruthenium complex [{RuCl2(p-cymene)}2]6f has been developed. These reagents reacted smoothly with amines and alcohols to give the corresponding N- and O-acylated compounds in excellent yields. This acylation method has been applied to the synthesis of hydrophilic 3′-N-acylated oxaunomycin derivatives 13a, b.