Indoline

Chemical Properties

2,3-Dihydroindole [496-15-1], indoline C8H9N, Mr 119.16, bp 229 – 230 ℃(101.3 kPa), is a colorless liquid, which is volatile in steam and soluble in diethyl ether, acetone, and benzene, but only slightly soluble in water. Indoline is obtained by hydrogenation of indole or by catalytic cyclodehydration of 2-(2-aminophenyl)ethanol. A range of pharmaceuticals, as well as fungicides and bactericides, can be produced from indoline.

Uses

As an indole derivative, Indoline can be used in the preparation of various medicinal compounds such as potential α1-adrenoceptor (α1-AR) antagonists.

Uses

Indole is used in perfumery and in preparing tryptophan, one of the 20 amino acids commonly found in animal proteins. It has important application in the industry of plant growth. It is used to prepare indoleacetic acid (auxin) and other plant growth substances which help the development of roots in plant. Indole and its derivatives are widely used in making perfumes, dyes, agrochemicals and medicines.

Uses

Reactant for preparation of:

• Inhibitors of NOD1-Induced Nuclear Factor-κB Activation
• Sphingosine-1-phosphate 4(S1P4) receptor antagonists
• Cytotoxic cell cycle inhibitors
• 2-Aminopyridines
• PET agent for imaging of protein kinase C (PKC)
• Sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors for the management of hyperglycemia in diabetes
• α4β2-Nicotinic acetylcholine receptor-selective partial agonists
• mGlu4 positive allosteric modulators
• Bacterial biofilm inhibitors
• Serotonin 5-HT6 receptor antagonists

Definition

ChEBI: Indoline is a member of indoles.

Application

In organic chemistry, indoline derivatives are widely used as chiral auxiliary groups or chiral ligands, playing a crucial role in asymmetric synthesis. For example, (S)-Indoline-2-methanol is an important starting material for the synthesis of many chiral compounds. Through asymmetric catalytic reactions, such as the asymmetric rearrangement reaction of iridium porphyrin-catalyzed indoles with aryl diazonium esters, chiral 2-indoline tertiary alcohols can be synthesized efficiently.

Synthesis Reference(s)

Journal of the American Chemical Society, 96, p. 7812, 1974 DOI: 10.1021/ja00832a035
Synthetic Communications, 13, p. 489, 1983 DOI: 10.1080/00397918308081827

Synthesis

Indolene is manufactured from (theoretically) 2 Mol. Indole plus 1 Mol. Hydroxycitronellal by condensation under heating. The proportions may vary slightly, and it is common practice to add Diethyl phthalate to the mixture prior to heating, so that the condensation product is somewhat protected against local overheating, and the finished product becomes light of color and fairly pourable at room temperature.