Related Experiment Video
Updated: Aug 15, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Substituted 6,7-dihydroimidazo[1,2-a]purin-9(4H)-ones
Abstract:
The synthesis of a series of substituted 6,7-dihydroimidazo[1,2-a]purin-9(4H)-ones is described. Several members of the series exhibit enhanced antiallergic and bronchodilator activity and reduced side effects as compared to theophylline. Structure-activity relationships and metabolic considerations are discussed for the series. Analogues substituted with a 4-(4-chlorobenzyl) moiety, such as 33 and 40, shown an optimal balance of antiallergic and bronchodilator activity and are of particular interest. Compound 33 is significantly more potent than theophylline against both metacholine- and antigen-induced bronchospasms, does not affect spontaneous motor activity, and shows minimal cardiovascular effects in the rat.
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Basicity of Heterocyclic Aromatic Amines
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Diazonium Group Substitution: –OH and –H
Nomenclature of Aromatic Compounds with Multiple Substituents
For disubstituted benzene derivatives, with two groups attached to the benzene ring, three constitutional isomers are possible. For example, consider dimethyl benzene, often called xylene, where the second methyl group can be substituted at the second, third, or fourth carbon. The relative position of the substituents is represented by prefixes ortho, meta, or...

