Process for the preparation of ethyl 3S-[[4-[[4-(aminoiminomethyl)phenyl]amino]-1,4-dioxobutyl]amino]-4-penty noate

A process for preparing ethyl 3S-amino-4-pentynoate, monohydrochloride having the following formula ##STR13## which comprises:

• (a) treating (trimethylsilyl)acetylene sequentially with n-butyllithium and 4-formylmorpholine in the presence of an aprotic solvent followed by acid hydrolysis to give 3-(trimethylsilyl)-2-propynal;
• (b) treating 3-(trimethylsilyl)-2-propynal, the product of step a, with lithium bis(trimethylsilyl)amide in the presence of an aprotic solvent to give N,3-bis(trimethylsilyl)-2-propyn-1-imine in situ, treating N,3-bis(trimethylsilyl)-2-propyn-1-imine with lithium t-butyl acetate followed by hydrolytic cleavage to give (.+-.)1,1-dimethylethyl 3-amino-5-(trimethylsilyl)-4-pentynoate;
• (c) treating (.+-.)1,1-dimethylethyl 3-amino-5-(trimethylsilyl)-4-pentynoate, the product of step b, with p-toluenesulfonic acid in the presence of aprotic solvents to give (.+-.)1,1-dimethylethyl 3-amino-5-(trimethylsilyl)-4-pentynoate, mono p-toluenesulfonic acid salt, treating the resulting salt with ethanol in the presence of p-toluenesulfonic acid, followed by neutralization to give (.+-.)ethyl 3-amino-5-(trimethylsilyl)-4-pentynoate;
• and
• (d) treating (.+-.)ethyl 3-amino-5-(trimethylsilyl)-4-pentynoate, the product of step c, with a catalytic amount of base in the presence of alkanol solvent followed by a catalytic amount of acid to give the desilylated (.+-.)ethyl 3-amino-4-pentynoate in situ, treating (.+-.)ethyl 3-amino-4-pentynoate with (R)-(-)-mandelic acid in the presence of aprotic solvents to give ethyl 3S-amino-4-pentynoate compounded with .alpha.R-hydroxybenzeneacetic acid;
• and
• (e) treating ethyl 3S-amino-4-pentynoate compounded with .alpha.R-hydroxybenzeneacetic acid, the product of step d, with gaseous hydrochloric acid in the presence of an aprotic solvent to give ethyl 3S-amino-4-pentynoate, monohydrochloride;
• with the understanding that when a pharmaceutically acceptable acid addition salt other than hydrochloride is desired the ethyl 3S-amino-4-pentynoate compounded with .alpha.R-hydroxybenzene acetic acid, the product of step d, is treated with the appropriate acid corresponding to the desired salt.