Diisopropylethylamine → (S)-4-(3-tert-butoxycarbonylmethyl-ureido)-5-(3'-chloro-biphenyl-4-yl)-2-methyl-pentanoic acid ethyl ester

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Reaction Steps

(S)-5-(3′-Chloro-biphenyl-4-yl)-4-isocyanato-2-methyl-pentanoic acid ethyl ester is prepared from (S)-4-amino-5-(3′-chloro-biphenyl-4-yl)-2-methyl-pentanoic acid ethyl ester hydrochloride (Intermediate 31) and triphosgene analogous to the procedure described for Example 6-1. Next, to a solution of tert-butyl 2-aminoacetate (140 mg, 1.065 mmol) in DMF (5 mL) is added DIEA (344 mg, 2.66 mmol). The solution is stirred at room temperature for 5 minutes then (S)-5-(3′-chloro-biphenyl-4-yl)-4-isocyanato-2-methyl-pentanoic acid ethyl ester (330 mg, 0.887 mmol) is added. The mixture is stirred at room temperature for 2 hours then the solvent is removed under reduced pressure to give (S)-4-(3-tert-butoxycarbonylmethyl-ureido)-5-(3′-chloro-biphenyl-4-yl)-2-methyl-pentanoic acid ethyl ester which is used directly in the following reaction.

Provenance & Evidence