L-色氨酸

4-氧杂-4,5,6,7-四氢苯并[B]呋喃-3-羧酸

4,5,6,7-四氢吲哚

1,5,6,7-四氢-4H-吲哚-4-酮

4-氧代-4,5,6,7-四氢苯并呋喃-3-羧酸乙酯