(S)-4-{4-[(2,4-Diamino-pteridin-6-ylmethyl)-methyl-amino]-benzoylamino}-4-methylcarbamoyl-butyric acid

tert-butyl N1-methyl-N2-(4-methylbenzoyl)-L-glutaminate

N5-benzyloxy-N1-methyl-N2-(4-methylbenzoyl)-L-glutamamide

(S)-4-(4-Methylamino-benzoylamino)-4-methylcarbamoyl-butyric acid tert-butyl ester

(S)-4-Methylcarbamoyl-4-{4-[methyl-(2,2,2-trifluoro-acetyl)-amino]-benzoylamino}-butyric acid tert-butyl ester