p-Toluenesulfonic acid → (S,S,S)-7-[2-[(1-ethoxycarbonyl-3-phenylpropyl)amino]-1-oxopropyl]-1,4-dithia-7-azaspiro[4.4]nonane-8-carboxylic acid, diphenylmethyl ester

Participants

Reaction Steps

To a cold (0°) solution of N-[1(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine (720 mg., 2.57 mmole) and (S)-1,4-dithia-7-azaspiro[4.4]nonane-8-carboxylic acid, diphenylmethyl ester, p-toluenesulfonate (1.06 g., 1.1 eq.) in 8 ml. of dry dimethylformamide under argon is added dropwise a solution of 0.61 ml. (1.1 eq.) of diphenylphosphoryl azide in 1 ml. of dimethylformamide. The reaction mixture is worked up according to the procedure of Example 95(f) to yield (S,S,S)-7-[2-[(1-ethoxycarbonyl-3-phenylpropyl)amino]-1-oxopropyl]-1,4-dithia-7-azaspiro[4.4]nonane-8-carboxylic acid, diphenylmethyl ester.

Provenance & Evidence