硫醚氧化制备砜
砜类化合物在天然产物及医药中间体中⾮常常见。虽然有很多⽅法合成砜，但最常见的⽅法是直接由硫醚或亚砜氧化得到。实现这⼀转化的常见的氧化剂有：H2O2, mCPBA, OXONE , NaClO, KMnO4，氧⽓等。将硫醚氧化成亚砜的反应速度要⽐将硫醚氧化成砜的反应速度快很多，所以硫醚更容易被氧化到亚砜的阶段，要氧化得到砜通常需要在催化剂存在下氧化才能实现。
⼀、H2O2
slowlyH2O2是氧化制备砜的最常⽤的氧化剂。反应后副产物是⽔，不引⼊其他杂质，产物容易分离。但是要氧化硫醚得到砜，需要加⼊其他催化剂，如Ti, Mo, Fe, V, W, Re, Ru, Sc, Zr和Mn等，另外还有有机催化剂，如Cyanuric chloride (CC)，六氯环三磷腈等。
oet【 J. Org. Chem. 1993, 58, 1672】
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托福考试报名时间
方向英文
a Sulfide (0.5 mmol), 50% H2O2, and WO3/MCM-48 (5.0 wt %, 2-3
nm, 1.0 mol %) in MeOH (2.0 mL). b Condition A: 1.1 equiv of H2O2, 25
°C, 4 h. Condition B: 3.0 equiv of H2O2, 60 °C, 12 h. c Average NMRbusted
yields of two runs bad on an internal standard (anisole), and the numbers in parenthes are isola
ted yields.【 Org. Lett. 2005, 7, 5015–5018】
General Procedure for the Preparation of Sulfones. To the mixture of sulfide (1 mmol) and TAPC (0.1 mmol, 0.035 g) was added 30% H2O2 (2 mmol, 0.2 mL). The mixture was stirred at room temperature for the appropriate period of time until the complete consumption of starting material as obrved by TLC. After the completion of the reaction,H2O(10 mL) was added to the reaction mixtur
e. The residue was then extracted with EtOAc (45 mL), and the combined extracts were dried (MgSO4). The filtrate was evaporated and the corresponding sulfone was obtained as the only product (Table 1). An identical procedure was employed using sulfoxide (1 mmol) 30%H2O2 (1 mmol, 0.1 mL) and TAPC (0.1 mmol, 0.035 g), for the oxidation of sulfoxides to sulfones
【 J. Org. Chem. 2010, 75, 6208–6213】
General procedure for the oxidation of sulfides to sulfoxides
General procedure for the oxidation of sulfides to sulfoxides
In a 25ml round-bottom flask, to a solution of sulfide (1 mmol) in THF (4 ml), 35% H2O2 (1 equivalent) and CC (0.4 mmol) were added successively and the mixture was stirred magnetically for the time indicated in Table 2. The progress of the reaction was monitored
by TLC. After completion of the reaction, solid CA precipitate was filtered and washed with diethyl ether. The filtrate was neutralized by adding (10%) NaHCO3. The product was extracted with diethyl ether (3 × 5 ml) and the combined extracts were dried (Na2SO4). The solvent was removed under reduced pressure to give the corresponding pure sulfoxide. Further purification was achieved by short-column chromatography on silica gel with EtOAc/n-hexane (1:2) as the eluent.研究生报名及考试时间
General procedure for the oxidation of sulfides to sulfones
In a 25ml round-bottom flask, to a solution of sulfide (1 mmol) in THF (6 ml), 35% H2O2 (2.5 equivalents) and CC (1 mmol) were added successively and the mixture was stirred magnetically for the time indicated in Table 2. The progress of the reaction was monitored by TLC. After completion of the reaction, solid CA precipitate was filtered and washed with diethyl ether. The combined filtrates were neutralized by adding (10%) NaHCO3. The product was extracted with diethyl ether (3 × 5 ml) and the combined extracts were dried (Na2SO4). Evaporation of the solvent
under reduced pressure gave the corresponding pure sulfone in most cas. Further purification was achieved by recrystallization from EtOH.
【 Journal of Sulfur Chemistry , 2011, 32, 435-441 】
Typical procedure.UHP (12 mol) was introduced to the solution of the trifluoroacetic anhydride (9 mmol) in acetonitrile (10 cm3) and the resulting solution was mixed at room temperature for 20 min. The substrate 1 (3 mmol for dialkyl-, and 1.5 mmol for alkyl-aryl or diary1 sulfides) was then added w
mantraith stimng. The progress of the reaction was followed by TLC (silica gel; hexane-acetone 3:l). After completion of oxidation water (10 cm3) was added to the reaction mixture. The aqueous pha was extracted with dichloromethane (3x7 cm3), and the combined organic layer was washed with water (2x7 cm3). The combined extracts were then dried over sodium sulfate, filtered an concentrated in vacuo. Flash silica gel chromatography of the residue with dichloromethane-ethyl acetate 10: 1 as eluent gave of pure sulfones 2 (cf. Table 1).
General procedure for the preparation of sulfonesTo the mixture of sulfide (1 mmol) and 30% H2O2 (4 mmol, 0.4 ml) in acetonitrile (5 ml), TiCl4 (1 mmol, 0.11 ml) was added. The mixture was stirred at room temperature for an appropriate period of time (Table 3). A white solid (TiO2) immediately precipitated. After the complete Downloaded by [Florida State University] at 04:14 26 September 2014 162 K. Bahrami et al. consumption of the starting material as obrved by TLC, the reaction mixture was filtered to give TiO2. The filtrate was poured into water (10 ml). The residue was then extracted with EtOAc (4 × 5 ml) and the combined extracts were dried (MgSO4). The filtrate was evaporated and the抵赖
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