Synthesis and antiallergy activity of 5-oxo-5H-thiazolo[2,3-b]quinazolinecarboxylic acids

Abstract

A series of substituted 5-oxo-5H-thiazolo[2,3-b]quinazolinecarboxylic acids was prepared and evaluated in the rat PCA test for antiallergic activity. The analogues that exhibited the highest oral activity were the 7-methoxy, 7-methylthio, and 7-isopropyl in the 2-carboxylic acid series and the 2-isopropyl in the 7-carboxylic acid series.

Preparation of Fused Tetracyclic Quinazolinones by Combinations of Aza‐Wittig Methodologies and CuI‐Catalysed Heteroarylation Processes

“…A number of synthetic methods for the preparation of this ring system have been developed. These include reactions between heteroaromatic 2-amino esters and 2-(methylthio)-2-thiazoline, [15] solid-phase methods, [16] condensations of substituted anthranilic acids or esters with methyl 2-chlorothiazole-5-carboxylate, [17] and the electrochemical oxidation of catechols in the presence of 2-mercapto-3H-quinazolin-4-one. [18] Scheme 4.…”

Synthesis of Substituted 4-Oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines and 4-Oxo-3,4-dihydroquinazoline-2-thioles

“…We have recently reported the unusual intramolecular cyclization of 3-(2-aminophenyl)-4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines (obtained using approach 2 (vide supra) by reacting 6 { 1 , 3 } with phenylenediamine, 8 { 6 }) into methyl benzimidazo[1,2 -c ]quinazoline-6(5 H )-thione-3-carboxylates, which are of great interest as potentially biologically active substances. , In particular, the parent ester, methyl benzimidazo[1,2 -c ]quinazoline-6(5 H )-thione-3-carboxylate ( 18 ), was hydrolyzed into benzimidazo[1,2 -c ]quinazoline-6(5 H )-thione-3-carboxylic acid ( 19) . Acid 19 was then employed in the synthesis of a new benzimidazo[1,2 -c ]quinazoline-6(5 H )-thione-3-carboxamide library, 20 , − 2021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172 and S-substituted 6-mercaptobenzimidazo[1,2 -c ]quinazoline-3-carboxamide library, 21 { 1 − 48 }. Library 20 was obtained by parallel synthesis from acid 19 and various primary, 7 , and secondary, 12 , amines by the carbonyldiimidazole method.…”

“…A large number of quinazoline derivatives, which contain the 4-oxo-2-thioxo-1,2,3,4-pyrimidine or 4-oxo-3,4-dihydropyrimidine-2-thiole structural motifs in their heterocyclic rings, possess a wide range of biological activities and provide an incentive for further exploration of this class of compounds as potential drug precursors. − The synthetic methods leading to these quinazoline derivatives are well-established and include the cyclization of N , N ‘ -disubstituted thioureas into 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines ( 1 ). The N , N ‘ -disubstituted thioureas used are generated in situ by reacting alkyl anthranilates with isothiocyanates or by reacting 2-(methylcarboxy)benzeneisothiocyanates with primary amines.…”

Synthesis of novel 2‐amino‐1,3‐thiazole‐5‐carboxylates utilising ultrasonic and thermally mediated aminolysis

“…Calcd for C 8 H 12 N 2 O 3 S: C,44.43;H,5.59;N,12.95;M +• 216.0569. Found: C,44.55;H,5.65;N,12.96;216.0570. Ethyl 2-N-Valinol-1,3-thiazole-5-carboxylate (8).…”