Organosilicon Synthesis of Isocyanates:III.Synthesis of Aliphatic,Carbocyclic,Aromatic,and Alkylaromatic Isocyanatocatboxylic Acid Esters

摘要

A series of aminoacid esters was prepared by treating the aminoacid suspensions in ethanol with thionyl chloride.Best conversion of aminoacid esters to corresponding isocyanates was achieved in the case of aromatic and carbocyclic aminoesters by phosgeneation of their N-silyl derivatives,and in the case of aliphatic and alkylaromatic aminoesters by phosgeneation of O-silyl or N,O-bissilylurethanes on their basis.In the last case additional step of esterification of the by-products isocyanatoalkylcarboxylic acid chlorides is reqired after phosgeneation.Unusual generation of cynnamates and intramolecular N->O-migration of tri-methylsilyl group in the solutions of silylated alkylaromatic beta-aminoacid esters were found.