保险粉高效制备砜新方法

【Org. Process Res. Dev. 2018, 22, 888–897】

2020年，华东师范大学姜雪峰教授课题组，开发了一种利用保险粉（连二亚硫酸钠），高效制备芳基烷基砜的方法。利用芳基卤代物，连二亚硫酸钠和磷酸酯在Pd(dppf)Cl₂(0.2 mol%)催化下一步合成芳基烷基砜。而用二氧化硫脲代替保险粉，无需过渡金属催化可以直接制备烷基烷基砜【Green Chem., 2020,22, 322-326】。

该方法利用稳定易得的磷酸酯提供烷基，利用连二亚硫酸钠作为二氧化硫源，易于操作，砜左右基团的自由变化让该方法实现了“模块组装”，获得了曾经许多难以获得的挑战性砜结构。

反应操作

II. General procedure for the alkyl alkyl sulfones synthesis

Under a N₂atmosphere, alkyl bromide 1 (0.5 mmol), thiourea dioxide (162.2 mg, 1.5 mmol), PO(OR₂)₃(1.5 mmol), KI (166.0 mg, 1.0 mmol), TBAI (92.3 mg, 0.25 mmol), Cs₂CO₃(325.8 mg, 1.0 mmol) and DMSO (2 mL) were added to a Schlenk tube. The reaction was stirred at 80 ^oC for 15 h, and water (25 mL) was added. The solution was extracted with ethyl acetate and organic layers were combined, dried over Na2SO4. After evaporation of solvent, the residue was purified by column chromatography to give the corresponding products 2.

III. General procedure for the aryl alkyl sulfones synthesis

Under a N₂atmosphere, alkyl iodide 1 (0.5 mmol), Na₂S₂O₄(261.2 mg, 1.5 mmol), PO(OR₂)₃(1.5 mmol), PdCl₂dppf (0.7 mg, 0.001 mmol), TBAB (241.8 mg, 0.75 mmol) and DMSO (5 mL) were added to a Schlenk tube. The reaction was stirred at 120 ^oC for 15 h, and water (25 mL) was added. The solution was extracted with ethyl acetate and organic layers were combined, dried over Na₂SO₄. After evaporation of solvent, the residue was purified by column chromatography to give the corresponding products 3.

参考文献

General sulfone construction via sulfur dioxide surrogate con

Green Chem., 2020,22, 322-326。