120493-42-7 2-(4-Chlorophenyl)-1,1-dimethylethyl 2-amino-3-methylbutanoate Gea 857 Gea-857 L-Valine, 2-(4-chlorophenyl)-1,1-dimethylethyl ester Valine, 2-(4-chlorophenyl)-1,1-dimethylethyl ester