反应详情

To a solution of 2-chloro-5-[(methylthio)methyl]pyridine (A) (7.60 g, 40 mmol) in chloroform (100 mL) cooled in ice-water bath was added a solution of 70-75% m-chloroperbenzoic acid (mCPBA, 10.51 g, ca 44 mmol) in chloroform (110 mL) over a period of 1.5 h under stirring. The stirring was continued for another 1 h at 0° C. Methanol (12 mL) was added to the mixture, which was then bubbled with ammonia gas to precipitate the benzoic acid and the extra mCPBA if any. TLC showed there was small amount of unreacted starting material in the reaction mixture. Most of the ammonium salt was removed by filtration. The filtrate was concentrated before it was loaded onto a Et3N-treated silica gel plug, which was eluted with 10% MeOH in CH2Cl2 to give 7.6 g of 2-chloro-5-[(methylsulfinyl)methyl]pyridine (B) in 92% yield as a colorless oil that turned into a white solid upon drying in vacuo (m.p. 72-74° C.). LC-MS (ELSD): mass calcd for C7H8ClNOS [M+H]+ 190.67. Found: 190.21.

1. customwas then bubbled with ammonia gas
2. customto precipitate the benzoic acid
3. customMost of the ammonium salt was removed by filtration
4. concentrationThe filtrate was concentrated before it
5. additiontreated silica gel plug, which
6. washwas eluted with 10% MeOH in CH2Cl2