Benzopyrones. 7. Synthesis and antiallergic activity of some 2-(5-tetrazolyl)chromones

Abstract

Antiallergic properties in the chromone series appear2"4 to be largely confined to those compounds which contain a carboxyl group at C-2. Replacement of a carboxyl by a 5tetrazolyl group in a biologically active carboxylic acid5"8 has sometimes resulted in retention of activity but rarely in an improvement in potency. This paper reports the synthesis and antiallergic properties of a number of chromones,9 such as Id and its substituted derivatives, which carry a 5-tetrazolyl group at C-2. The variations in structure are shown in Table I.

Synthesis and reactions of halogen-containing chromones

“…55 3-Bromochromone-2-carboxylic acid (25) and its ethyl ester (26) have been synthesised by two procedures. 54 According to one procedure, the condensation product obtained from 2-hydroxyacetophenone and diethyl oxalate and existing in the cyclic chromanone form 27 is made to react with bromine in chloroform in the presence of pyridine at 73 8C.…”

Pyranopyrazoles III synthesis of 1H‐pyrano[2,3‐c]pyrazol‐4‐ones

“…This mixture, as well as the esters 11 and 12, on acid hydrolysis afforded the ''corresponding'' acids 23-25. An ammonolysis [10] of ester 11 afforded the amide (26) in 79% yield. The amide (26) on dehydration with p-toluenesulfonyl chloride in pyridine [10] afforded the nitrile (27) which in turn, on reaction with sodium azide in…”

An Efficient Protocol for Facile Synthesis of New 5-Substituted-1H-Tetrazole Derivatives Using Copper-Doped Silica Cuprous Sulfate (CDSCS) as Heterogeneous Nano-Catalyst

“…Consequently, tetrazoles are widely applied in synthesis of many well-known drugs like losartan, [17][18][19] candesartan, 18,19 zolarsartan 18, 19 and valsartan. 17 In addition, tetrazoles exhibit varied biological activities such as antihypertensive, [17][18][19][20][21] antibacterial, 22,23 antifungal, 24,25 anticonvulsant, 26 anti-inflammatory, 27,28 antitubercular, 29 anticancer, 30 antineoplastic, 31 antiallergic, [32][33][34] and antiviral 35 especially anti-HIV 36 activities. The synthesis of tetrazole and its derivatives has attracted considerable attention since the broad utilities found for tetrazoles.…”