Methyl (s)-2-amino-3-(4'-cyano-[1,1'-biphenyl]-4-yl)propanoate → (S)-3-[(S)-2-(4'-cyano-biphenyl-4-yl)-1-methoxycarbonyl-ethylcarbamoyl]-7-hydroxy-6-nitro-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester

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Reaction Steps

(S)-7-hydroxy-6-nitro-3,4-dihydro-1H-isoquinoline-2,3-dicarboxylic acid 2-tert-butyl ester 3-methyl ester (5.1 mmol) was hydrolyzed and coupled with (S)-2-amino-3-(4′-cyano-biphenyl-4-yl)-propionic acid methyl ester (5.85 mmol) according to general procedures B and A to provide (S)-3-[(S)-2-(4′-cyano-biphenyl-4-yl)-1-methoxycarbonyl-ethylcarbamoyl]-7-hydroxy-6-nitro-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester (2.4 g). (S)-3-[(S)-2-(4′-cyano-biphenyl-4-yl)-1-methoxycarbonyl-ethylcarbamoyl]-7-hydroxy-6-nitro-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester (1.1 g) was dissolved in MeOH, Pd/C was added and the mixture stirred under balloon pressure of hydrogen for 1 h. Mixture was filtered through celite, washed with MeOH and EtOAc and concentrated to provide (S)-6-amino-3-[(S)-2-(4′-cyano-biphenyl-4-yl)-1-methoxycarbonyl-ethylcarbamoyl]-7-hydroxy-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester (1.06 g) which was used without further purification.

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