反应详情

5.0 g (19.0 mmol) piperidine-1,4-dicarboxylic acid monobenzyl ester were dissolved in 200 ml DCM and 4.16 ml SOCl2. After heating 2 h to reflux the volatile components were removed under reduced pressure. The residue was dissolved in 200 ml DCM and 3.29 g (22.8 mmol) 2,2-dimethyl-[1,3]dioxane-4,6-dione as well as 4.6 ml (57 mmol) pyridine were added. The reaction mixture was stirred at room temperature over night, washed twice with 1 N aqueous HCl and brine, dried over Na2SO4 and concentrated under reduced pressure to be subsequently submitted to column chromatography on silica gel with n-hexane/ethyl acetate to yield a product, which was dissolved in 50 ml DMSO/water (95:5) and heated to 70° C. for 3 h. The solvent was removed under reduced pressure and the residue was dissolved in ethyl acetate, washed twice with 0.1 N aqueous HCl, saturated aqueous Na2CO3 and brine, dried over Na2SO4 and evaporated under reduced pressure. The residue was purified by chromatography on silica gel using n-hexane/ethyl acetate as eluents to yield ketone (21).

1. temperatureAfter heating 2 h
2. temperatureto reflux the volatile components
3. customwere removed under reduced pressure
4. dissolutionThe residue was dissolved in 200 ml DCM
5. washwashed twice with 1 N aqueous HCl and brine
6. dry with materialdried over Na2SO4
7. concentrationconcentrated under reduced pressure
8. customto yield a product, which
9. temperatureheated to 70° C. for 3 h
10. customThe solvent was removed under reduced pressure
11. dissolutionthe residue was dissolved in ethyl acetate
12. washwashed twice with 0.1 N aqueous HCl, saturated aqueous Na2CO3 and brine
13. dry with materialdried over Na2SO4
14. customevaporated under reduced pressure
15. customThe residue was purified by chromatography on silica gel