EfficientN-acylation of sulfonamides using cesium salt of Wells–Dawson heteropolyacid as catalyst: Synthesis of newN-acyl sulfonamides and cyclic imides

Abstract

Preparation of N-acyl sulfonamides (2a-j), (3a-m), (5a-f) and cyclic imides (3n-r)Under nitrogen atmosphere, a mixture of sulfonamide (1 mmol), acylating agent (2 mmol) and Cs 5 HP 2 W 18 O 62 catalyst (5 mmol %) in water (2 mL), was stirred at room temperature to obtain (2a-j), (3a-m), (5a-f) and under reflux for (3n-r). Reaction was monitored by TLC. After completion of the reaction, the catalyst was removed by filtration. The filtrate was washed by water (10 mL) and extracted with EtOAc (3x15 mL). The combined organic layers were dried over anhydrous Na 2 SO 4 , then the solvent was evaporated in vacuum, and the crude compound was purified by flash chromatography (Merck silica gel 60 H, CH 2 Cl 2 /MeOH, 9:1) to afford the corresponding products.. NMR data of N-acyl sulfonamide derivatives (2a-j) N-(N-butylsulfamoyl)acetamide (2a)

An efficient green synthesis of new benzothiazoles containing sulfonamide or cyclic imide moieties

“…It should be noted that the intermediate carboxylic acid ( 2′a ) was already obtained in our recent work in the presence of 5 mmol% Cs 5 HP 2 W 18 O 62 as catalyst and water as solvent. Also, we found that the second step does take place only in the presence of this catalyst, hence its high efficiency.…”

“…From the point of synthetic simplicity, one‐pot reaction could provide a far more efficient and straightforward access to the target molecules. In the connection with our recent work, we envisioned that carboxylic acid (2′) produced in situ from sulfonamide (a) and cyclic anhydride may react with 2‐amino benzothiazole to form new product (b) containing both scaffolds: sulfonamide and benzothiazole (Scheme ). Initially, a one‐pot, one‐step protocol at room temperature was examined, using the same already optimized conditions in previous report (5 mmol% Cs 5 HP 2 W 18 O 62 as catalyst and water as solvent) for the preparation of ( 2a ) from sulfonamide ( 1a ), succinic anhydride and 2‐amino benzothiazole as the model reaction (Scheme ).…”

“…This latter catalyst has been reported in our recent work for the synthesis of substituted N ‐acylsulfonamides and cyclic imides containing sulfonyl group. It not only afforded the products in good to excellent yields, but also addresses challenges associated with catalysts such as ease of handling, recovery, safety and pollution.…”

“…Prompted by the aforementioned biological and pharmaceutical activities of benzothiazole derivatives, and as a part of an ongoing program aiming at the synthesis of new heterocyclic compounds . We describe herein an efficient procedure for the synthesis of a novel series of new benzothiazole derivatives, using ultrasound irradiation in the presence of Cesium salt of Wells‐Dawson heteropolyacid (Cs 5 HP 2 W 18 O 62 ) as catalyst.…”

“…All the chemicals were commercially available and used as received. Cesium salt of Wells‐Dawson heteropolyacid (Cs 5 HP 2 W 18 O 62 ) was prepared according to the literature, and characterized in our previous work by spectroscopic methods (IR, 31 PNMR). All the reactions were monitored by thin‐layer chromatography (TLC) carried out on 0.25 mm E. Merck silica gel plates (60F‐254) using UV light (254 nm) as the visualizing agent and ninhydrine solution and heat as developing agents.…”