HCID 20445881, compound → HCID 16793507, compound

Participants

Reaction Steps

Hydrolyze ethyl 2-oxo-3-p-cyanophenylpropionate, prepared in Example 72, by stirring in 5% sodium hydroxide at room temperature overnight, washing the reaction mixture with ether, acidifying the aqueous layer to pH 2 with conc. HCl, extracting the product into a mixture of ether and ethyl acetate, and removing the solvent to obtain 2-oxo-3-p-cyanophenylpropionic acid. Reductively couple the acid with the ethyl ester of L-homophenylalanine in the presence of sodium cyanoborohydride in the manner described in Example 13 and purify as described in that Example to obtain the mixture of diastereoisomers of N-(1(S)-ethoxycarbonyl-3-phenylpropyl)-D,L-p-cyanophenylalanine. Condense this with benzyl L-prolinate hydrochloride in dimethylformamide by the use of the diphenylphosphoryl azide reagent in the manner described in Example 13 to obtain the mixture of diastereoisomers of N-(1-(S)-carbethoxy-3-phenylpropyl)-D,L-p-cyanophenylalanyl-L-proline benzyl ester. Hydrogenate this intermediate in ethanol containing hydrogen chloride over palladium on carbon catalyst as described in Example 72 and work up as outlined there to obtain the desired product as a mixture of diastereoisomers.

Provenance & Evidence