Using the optimized conditions, we started investigating various sulfamidates and carboxylic acid derivatives. The reaction of the diethylamine containing sulfamidate (1b) with benzoic acid afforded desired product 3b in 46% yield. The reaction of sulfamidate 1b with p-toluic acid (2b) also formed product 3c but in low yield (17%). Further, reaction of methoxy substituted sulfamidate 1c with benzoic acid (2a) formed expected product 3c in moderate yield (52%). However, naphthyl sulfamidate (1d) did not react effectively giving 1,3,4-oxadiazole 3e in poor yield. Notably, bromo derivatives of sulfamidate 1e with benzoic acid (2a) did not afford the desired product (3f). Nonetheless, when sulfamidate 1c was reacted with pyridine carboxylic acid 2c, it formed the expected product with inseparable isomer in poor yield. Further, 4-hydroxybenzoic acid (2d) did not react with sulfamidate 1c to form desire product 3h. Next, we also sought to study the reactivity of other carboxylic acids with sulfamidates. So, apart from the products shown in Scheme 3, we also attempted other reactions to study reactivity of sulfamidate with other carboxylic acids (see supporting information, Scheme S1). For example, difluoro arylacetic acid, pyrimidine-2-carboxylic acid, terephthalic acid etc. -did not react well with sulfamidates. This observation intrigued us to study the reactivity of acyclic N-sulfonylimines with carboxylic acids after successful model reaction shown in Scheme 2. As shown in Scheme 4, acyclic N-sulfonylimine substrates were reacted with benzoic acids. Unlike halogenated sulfamidates, the reaction of halogenated acyclic N-sulfonylimine 4b reacted well with benzoic acid (2a) and 4-bromo-2-methyl benzoic acid (2b), giving desired products 5b and 5c in 53% and 37% yields, respectively. Further, the synthesis of 5d and 5e were achieved successfully using trimethoxy substituted N-sulfonylimine (4c), and 4-hydroxy 3-nitro substituted N-sulfonylimine (4e), and they were well tolerated to afford desired products 5d and 5e (70% and 64% yields, respectively). Scheme 4. Substrate scope for acyclic N-sulfonylimine with carboxylic acids used as training data.