1,2-Dichloroethane → Tert-butyl 6,8-dioxo-5-azaspiro[3.5]nonane-5-carboxylate

Participants

Reaction Steps

(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.

Provenance & Evidence