Cyclization of 2-(4-chlorobutanamido)benzoic acid to 2-(3-chloropropyl)-4H-benzo[3,1]oxazin-4-one using dehydrative cyclization agents

Functionalized 4H-3,1-benzoxazine-4-ones in 2-position have wide applications in synthesis of important heterocyclic compounds. Thus, development of simple and efficient protocols to prepare them using mild reaction conditions has received much attention.1-4 In this work, efficient methods for the synthesis of 2-(3-chloropropyl)-(4H)-benzoxazin-4-ones under mild reaction conditions are described. The coupling reaction of anthranilic acid derivatives with 4-chlorobutanoyl chloride following with dehydrocyclization of the produced amides 3 with simple reagents such as 2,4,6-trichloro[1,3,5]triazine (cyanuric chloride, TCT), N,N'-dicyclohexylcarbodiimide (DCC) and acetic anhydride (Ac2O) leads to the desired benzoxazin-4-ones 4 (Scheme 1). The notable advantages of these procedures are mild reaction conditions without need to use of any catalysts which produce high yields of the products with simple work-up of the reaction mixture.

کلیدواژه ها:

3 ، 1-Benzoxazin-4-ones ، Antranilic acid ، 4-Chlorobutanoyl chloride ، Cyclization agents