Indoline is an aromatic heterocyclic organic compound with the chemical formula C8H9N. The compound is based on the indole structure, but the 2-3 bond is saturated. Indoles and their derivatives continue to inspire the development of synthetic organic chemistry even years after their discovery. The specific scaffold is a privileged structure and is ubiquitous in pharmaceuticals and biologically active compounds. Fused indolines as indole derivatives are of particular interest as they are often found in natural products and bioactives such as strychnine and tryptanthrins (alkaloids), mitosanes and mitosenes (antitumor activity) and isatisine (antiviral activity).
Tetrahydroisoquinoline is an organic compound with the chemical formula C9H11N. It is classified as a secondary amine, obtained from isoquinoline by hydrogenation. The tetrahydroisoquinoline moiety forms the backbone of several natural, synthetic and semi-synthetic drugs approved for the treatment of cancer, pain, gout and various neurodegenerative diseases.