反应详情

81.0 g (0.40 mole) of 2-bromobenzylthiol were dissolved in 800 ml of tetrahydrofuran, and 516 ml of a solution containing 0.84 mole of butyllithium (as a 1.6 M solution in hexane) were added dropwise thereto over a period of 6 hours at a temperature of −78° C. The mixture was then stirred for 1.5 hours at the same temperature, after which 800 ml of a tetrahydrofuran solution containing 79.5 g (0.40 mole) of 1-t-butoxycarbonyl-4-piperidone was added dropwise thereto over a period of 3 hours. The solution was then stirred for a further 1 hour, and then a saturated aqueous solution of ammonium chloride was added, and the mixture was extracted with ethyl acetate. The organic extract was washed with a saturated aqueous solution of sodium chloride and then dried over anhydrous sodium sulfate. The solvent was then removed by distillation under reduced pressure. 2 liters of 4 N aqueous sulfuric acid were added to the residue, and then the mixture was heated under reflux for 14 hours. At the end of this time, the solution was made basic by the addition of 350 g (8.75 mole) of sodium hydroxide, whilst ice-cooling, and then 102 g (0.47 mole) of di-t-butyl dicarbonate were added thereto. The mixture was then stirred for 1 hour. At the end of this time, the product was extracted with methylene chloride, and the organic extract was washed with a saturated aqueous solution of sodium chloride and then dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the resulting residue was purified by silica gel column chromatography, using a 97:3 by volume mixture of hexane and ethyl acetate as the eluent, to give 56 g of the title compound as white crystals, melting at 131.0-132.5° C. (after crystallisation from hexane/ethyl acetate).

1. additionwere added dropwise
2. additionwas added dropwise
3. waitover a period of 3 hours
4. stirringThe solution was then stirred for a further 1 hour
5. extractionthe mixture was extracted with ethyl acetate
6. extractionThe organic extract
7. washwas washed with a saturated aqueous solution of sodium chloride
8. dry with materialdried over anhydrous sodium sulfate
9. customThe solvent was then removed by distillation under reduced pressure
10. addition2 liters of 4 N aqueous sulfuric acid were added to the residue
11. temperaturethe mixture was heated
12. temperatureunder reflux for 14 hours
13. temperaturecooling
14. stirringThe mixture was then stirred for 1 hour
15. extractionAt the end of this time, the product was extracted with methylene chloride
16. extractionthe organic extract
17. washwas washed with a saturated aqueous solution of sodium chloride
18. dry with materialdried over anhydrous sodium sulfate
19. customThe solvent was removed by distillation under reduced pressure
20. customthe resulting residue was purified by silica gel column chromatography
21. additionby volume mixture of hexane and ethyl acetate as the eluent
22. customto give
23. custom56 g of the title compound as white crystals, melting at 131.0-132.5° C. (after crystallisation from hexane/ethyl acetate)