反应详情

To a solution of 0.55 g (1.65 mmol) of 5-(Methoxymethoxy)-2,2,4-trimethyl-7-pentyl-2H-1-benzopyran-3-propanoic acid in 60 mL of tert-butyl alcohol (MCB Chem. Co.) under argon was added 4.16 g (10 eq.) of pyridinium para-toluenesulfonic acid (Aldrich) and the reaction mixture boiled under reflux for 1 hr. The reaction mixture was cooled with an ice-water bath and then partitioned between 500 mL of EtOAc and 100 mL of water. The phases were separated and the organic phase washed with water (5×100 mL), half-sat. aq. NaCl (1×100 mL), sat. aq. NaCi (1×100 mL), dried (Na2SO4), evaporated under reduced pressure and the residue dried under high vacuum to give discolored solids. The solids were redissolved and subjected to column chromatography on flash-grade silica gel, eluting with 10% MeOH-CHCl3. The fractions containing product were combined and solvent removed under reduced pressure to give, after drying under high vacuum, 143 mg of 5-Hydroxy-2,2,4-trimethyl-7-pentyl-2H-1-benzopyran-3-propanoic acid as a glass/amorphous solid. HR EI MS: Calc M+, 332.1988; Observed, 332.1985.

1. temperatureunder reflux for 1 hr
2. temperatureThe reaction mixture was cooled with an ice-water bath
3. custompartitioned between 500 mL of EtOAc and 100 mL of water
4. customThe phases were separated
5. washthe organic phase washed with water (5×100 mL), half-sat
6. dry with materialaq. NaCl (1×100 mL), sat. aq. NaCi (1×100 mL), dried (Na2SO4)
7. customevaporated under reduced pressure
8. customthe residue dried under high vacuum
9. customto give
10. dissolutionThe solids were redissolved
11. washeluting with 10% MeOH-CHCl3
12. additionThe fractions containing product
13. customsolvent removed under reduced pressure
14. customto give
15. dry with materialafter drying under high vacuum, 143 mg of 5-Hydroxy-2,2,4-trimethyl-7-pentyl-2H-1-benzopyran-3-propanoic acid as a glass/amorphous solid