反应详情

Boc-β-alanine (25 g, 132 mmol), Meldrum's acid (20.9 g, 145 mmol) and 4-dimethylaminopyridine (DMAP, 24.2 g, 198 mmol) were dissolved in 700 mL of dry dichloromethane (DCM) at 0° C. under nitrogen atmosphere. To this solution 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30.4 g, 158 mmol) was added. The resulting solution was allowed to reach room temperature and stirred overnight. The reaction mixture was washed (0.5 L×4) with 5% KHSO4 aqueous solution. The organic layer was dried over anh. Na2SO4, filtered and evaporated under vacuum, affording crude [3-(2,2-dimethyl-4,6-dioxo-[1,3]dioxan-5-yl)-3-oxo-propyl]-carbamic acid tert-butyl ester that was dissolved in 600 mL of ethylacetate and refluxed for 4 hours. The solvent was reduced to 150 mL under vacuum and the resulting solution was allowed to crystallize at 4° C. overnight. The solid was filtered and washed with cold ethyl acetate affording 18.4 g (65% yield) of the title compound.

1. customto reach room temperature
2. washThe reaction mixture was washed (0.5 L×4) with 5% KHSO4 aqueous solution
3. dry with materialThe organic layer was dried over anh. Na2SO4
4. filtrationfiltered
5. customevaporated under vacuum