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).
Thiadiazoles are a subfamily of azoles. Structurally, they are five-membered heterocyclic compounds containing two nitrogen atoms and one sulfur atom, and two double bonds, forming an aromatic ring. Depending on the relative positions of the heteroatoms, there are four possible structures; these forms do not interconvert and are therefore structural isomers rather than tautomers. These compounds themselves are rarely synthesized and have no particular utility, however, compounds that use them as structural motifs are fairly common in pharmacology.