23dihydroindole

23-dihydroindole, commonly referred to as 2,3-dihydroindole or indoline, is a bicyclic nitrogen-containing heterocycle. It consists of a benzene ring fused to a five-membered pyrroline ring, with the 2- and 3-positions of that ring saturated relative to indole. Its molecular formula is C8H9N and its IUPAC name is 2,3-dihydro-1H-indole.

Indoline is a secondary amine within a compact ring system, giving it distinct reactivity compared with indole. The saturation of the five-membered ring reduces aromatic character and alters base strength and nucleophilicity at nitrogen. It is typically handled as a relatively reactive amine suitable for further functionalization.

Preparation and applications often center on its role as a versatile synthetic building block. Indoline is commonly prepared by catalytic hydrogenation of indole using hydrogen in the presence of catalysts such as palladium on charcoal (Pd/C) or related catalysts. Once prepared, it can undergo N-alkylation or N-acylation, reduction, or oxidation to related products. Its rigid bicyclic framework provides a useful scaffold in medicinal chemistry for the development of indoline-containing pharmaceuticals, natural products, and dye precursors.

Safety and handling follow standard precautions for secondary amines and heterocyclic compounds. Typical concerns include irritation and potential sensitization; appropriate protective equipment and ventilation are advised. The compound is used and stored under conditions appropriate for small-molecule organic amines. See also indole and indole derivatives for related structures and transformations.