反应详情

(1-tert-Butoxycarbonylamino-cyclobutyl)-acetic acid (6 g; 26 mmol) (Eur.J.Med.Chem. 34 (1999) 363), EDC (7.5 g; 39 mmol) DMAP (4.8 g; 39 mmol) and Meldrum's acid (3.77 g; 26 mmol) in CH2Cl2 (120 ml) are stirred at room temperature over night and poured on 2N HCl/water (40 ml/400 ml). The aqueous phase is extracted with CH2Cl2 twice, the organic phases are combined and dried over Na2SO4 and evaporated to dryness. The orange-colored residue is taken up in ethyl acetate (200 ml) and refluxed for 2.5 hours, diluted with hexanes (600 ml) and purified via chromatography (SiO2; Hexanes/acetone 92:8) yielding the title compound as yellowish crystals in a modest purity, which is sufficient to perform the next steps.

1. extractionThe aqueous phase is extracted with CH2Cl2 twice
2. dry with materialdried over Na2SO4
3. customevaporated to dryness
4. temperaturerefluxed for 2.5 hours
5. additiondiluted with hexanes (600 ml)
6. custompurified via chromatography (SiO2; Hexanes/acetone 92:8)