(2S)-2-amino-4-chloropent-4-enoic acid (2S)-2-amino-4-chloro-pent-4-enoic acid 55528-30-8 (S)-2-amino-4-chloro-4-pentenoic acid CHEBI:15885 L-2-amino-4-chloropent-4-enoic acid 2-Amino-4-chloro-4-pentenoic acid C04075