Synthesis of imidapril hydrochloride

N-benzyloxycarbonyl-L-asparagine underwent cyclization, esterification, methylation, De-Cbz reaction to afford the key intermediate (4S)-1-methyl-2-oxo-imidazolin-4-carboxylic acid tert-butyl, followed by acylation with N-[(S)-1-ethyoxyoxo-3-phenylpropyl]-L-alanine and removal of tertbutyl group using hydrochloride gas to generate imidapril hydrochloride. The total yield is about 26%(based on N-Carbobenzyloxy-L-asparagine).