Synthesis And Study Of 2-Acylimino-3-aryl-1, 3-thiazoline Derivatives

It is well known that the typical organic synthesis has been carried out in organic solvents. However, most of organic solvents are flammable, volatile and toxic. Recently years, with the increasing concern on the environmental of human being lived, the use of water as a medium in organic reaction has received considerable attention due to its several advantages, for example, it is cheaper, nonflammable, nontoxic and easily available on the earth, and had incommutable advantages relative to organic solvents.Combination of microwave irradiation and solvent-free strategy in organic reaction has attracted many interests in chemical industry. Indeed, most of solvent-free organic reactions occurred in solid state, the tightly and regularly arranged structures of solids made the reactions proceed more efficiently and selectively than solution ones. Furthermore, organic reactions promoted by microwave under solvent-free condition have advantages of avoiding the use of organic solvents, is clean, effective and economical, in which the safety is largely increased, workup procedure is considerably simplified and the cost is greatly reduced.In summary, the aqueous media route and the microwave irradiation solvent-free design were all based on the green-chemistry and avoided the pollution of environment.Part I: Green synthesis of 2-acylimino-3-aryl-4-methyl/phenyl-1,3-thiazoline derivatives.Series I: 12 New 2-benzoylimino-3-aryl-4-methyl/phenyl-1,3-thiazoline derivatives 2a～2I were synthesized by condensation reaction of N-aryl-N'-benzoyl thioureas withα-bromoacetone andα-bromoacetophenone under refluxing.Series II: The one-pot two-step synthesis for 22 new 2-(5-aryl-2-furoylimino)-3-aryl -4-methyl/phenyl-1,3-thiazoline derivatives IV～V by treatment of N-aryl-N'(5-aryl-2-furoyl) thiourea withα-bromoacetone andα-bromoacetophenone under aqueous media. The intermediate thiourea obtained from reactions of 5-aryl-2-furoyl chloride with ammonium thiocyanate and arylamines in the presence of benzyltriethylammonium chloride (TEBA) as catalyst in H₂O at room temperature and without isolation. Compared to classical reaction in organic solvents, this method consistently has the advantage of short reaction times, simple work-up procedure and environmentally friendly.Series III: 20 New 2-(2-benzofuroylimino)-3-aryl-4-methyl/phenyl-1,3-thiazoline derivatives 4a～4t were synthesized by condensation reaction of N-aryl-N'-(2-benzofuroyl) thiourea withα-bromoacetone andα-bromoacetophenone on alumina using microwave irradiation. The structure of the compounds and the reaction mechanism were supported by X-ray crystal structure analysis. We studied different affects of varies conditions (such as, ratios, irradiation power and time) on the reactions.Part II: Green synthesis of N-aryl-2-benzofuran amides and N, N -diaryl-2-nitro-1,4-phenylenedioxydiacetamides.The reactions of 2-benzofurancarbonyl chloride with equivalent of various arylamines under the condition of solventless and microwave irradiation expeditiously gained seriesâ…¢₁-â…¢₁₃. The reactions of N,N'-diaryl-2-nitro-1,4-phenylenedioxydiacetyl chloride with 2 eq. of various arylamines by grinding under solventless and room-temperature conditions expeditiously afforded series IV₁～IV₁₂. These synthetic strategies compared with traditional solution protocol have the advantages of no organic solvent pollution, elevated reaction rate, high yield and simple work-up procedure.The structures of all compounds were confirmed by elemental analysis, IR, ¹H NMR and ¹³C NMR.