Microwave enhanced synthesis of 4-aminoquinazolines

—An improved method for the synthesis of 2-aminoquinolines utilizing microwave-assisted synthesis is described. The process involves rapid microwave irradiation of secondary amines and aldehydes to form enamines followed by the addition of 2-azidobenzophenones with subsequent irradiation to produce the 2-aminoquinoline derivatives. Purification of the products is accomplished in a streamlined manner using solid-phase extraction techniques to produce the desired products in high yields and purity.

Arkivoc, 2005

A fast, highly efficient and environmentally friendly microwave accelerated solvent-free procedure for the synthesis of a series of differently N-substituted 4-amino-2-methylquinazolines is developed. The transformation proceeded very clean, without any traces of side products. It was shown that aliphatic amines react quantitatively after 5 min irradiation, while the rate of conversion by anilines strongly depends on the place and the type of the substituents in their molecules. The results are explained by the competition of the steric and electronic effects of the amine substituents. The by-product of the reaction, hydrogen chloride, is quantitatively quenched as ammonium salts by the amines, used as nucleophiles, thus preventing its release into the environment.

Green Chemistry, 2011

A solvent-and catalyst-free synthesis of dihydroquinazolines is described. 2,4-Disubstituted-1,2-dihydroquinazolines can be readily obtained from 2-aminobenzophenone and aldehydes under microwave irradiation using urea as an environmentally benign source of ammonia, with a small amount of the corresponding quinazolines as the minor product. The reaction is simple, clean and excellent yields are obtained within minutes.

Letters in Organic Chemistry, 2017

Background: Aminoisoquinolines are an important class of heterocyclic compounds. These compounds present a wide range of pharmacological properties including antimalaric, anticonvulsant and anti-inflammatory. Although several preparation routes may be found in the literature for the preparation of these compounds, many of these methods present difficulties, including laborious isolation methods, drastic conditions and extended reaction times. Methods: The synthesis of N-substituted 1-alkyl and 1-aryl-3-aminoisoquinolines is developed through the reaction of 2-acylphenylacetonitriles with amines under microwave irradiation conditions. The reactions were performed in ethanol as a solvent without the use of catalyst. In parallel, these reactions were performed under identical conditions of temperature using P 2 O 5 /SiO 2 as a catalyst in different amounts. Results: A series of N-substituted 1-alkyl and 1-aryl-3-aminoisoquinolines were synthesized using microwave irradiation with as high selectivity, short reaction times and without the use of catalyst. The use of P 2 O 5 /SiO 2 as catalyst under microwave irradiation conditions was not effective for these reactions. Conclusion: The results show an efficient method for the synthesis of N-substituted 1-alkyl and 1-aryl-3-aminoisoquinolines by the reaction of 2-acylphenylacetonitriles with amines using microwave irradiation. Some important advantages for this method include a strong decrease in reaction time, a good selectivity, and the absence of catalyst, with simplicity in operation and a benefit to the environment.

Australian Journal of Chemistry, 2007

An efficient synthesis of 4-aminoaryl/alkyl-7-chloroquinolines and 2-aminoaryl/alkylbenzothiazoles has been developed by microwave-accelerated regioselective aromatic nucleophilic substitution of 4,7-dichloroquinoline and 2-chlorobenzothiazole with aromatic and aliphatic amines under solvent-free conditions in the absence of any added protic or Lewis acid catalyst. Chemoselective reaction with the amino group in preference to the phenolic hydroxy group was observed. Thus, the treatment of 4,7-dichloroquinoline (1 equiv.) with a mixture of aniline (2 equiv.) and phenol (2 equiv.) afforded exclusive formation of 4-aminophenyl-7-chloroquinoline. When 4,7-dichloroquinoline (1 equiv.) was separately treated with 2-aminophenol (2 equiv.) and 4-aminophenol (2 equiv.), 4-(2′-hydroxyphenyl)-7-chloroquinoline and 4-(4′-hydroxyphenyl)-7-chloroquinoline, respectively, were formed.

A facile microwave assisted one-pot synthetic protocol has been devised for the synthesis of 3,3′-(alkanediyl) bis (1-phenyl-1,2,3,4,7,8hexahydroquinazolin-5(6H)-ones (2a-c), 3,3′-(1,4-phenylene) bis (1-phenyl-1,2,3,4,7,8-hexahydroquinazolin-5(6H)-one (2d),3,3′-(alkanediyl) bis (7,7dimethyl-1-phenyl-1,2,3,4,7,8-hexahydroquinazolin-5(6H)-ones (2e-g) and 3,3′-(1,4-phenylene) bis(7,7-dimethyl-1-phenyl-1,2,3,4,7,8-hexahydroquinazolin-5(6H)-one (2h) by the cyclocondensation of cyclic enaminones 1a, b with diamines and formaldehyde.

Orbital the Electronic Journal of Chemistry, 2011

Novel hexahydroquinazolin-5(6H)-ones 3a-j have been synthesized in good yields by the reaction of enaminones 2a-b with primary amines and formaldehyde under the influence microwaves. Enaminones 2a-b have also been reacted with diamines and formaldehyde under similar conditions resulting in hitherto unreported bishexahydroquinazolin-5(6H)-ones 4a-d and 5a-d. The structures of the molecules have been established with the help of spectral and analytical data.

ChemInform, 2010

Keywords: 3-hydrazinoquinoxalin-2(1H)-one, imines, Gram-positive bacteria.

ChemInform, 2009

Keywords: 3-hydrazinoquinoxalin-2(1H)-one, imines, Gram-positive bacteria.

2017

The synthesis of quinazolinones using a microwave method and their functionalization with the Mitsunobu reaction were investigated. The microwave method was proven to be rapid, simple and efficient in the synthesis of the starting quinazolinone. The results show an increase of obtained yields when compared with the conventional thermal method and the formation of the final derivatives in one step reaction without the activation of the alcohol function. The title quinazolinones were functionalized with a variety of variously substituted phenols using the Mitsunobu reaction to produce the corresponding new ether bridged derivatives in a 57-87% yield.