A mixture of ethyl 5-methoxy-4-hydroxy-2-oxo-2′,3′,5′,6′-tetrahydro-spiro[naphthalene-1,4′-pyran]-3-carboxylate (44 mg, 132 μmol), tert-butyl 2-aminoacetate hydrochloride (33 mg, 199 μmol) in 2 mL dioxane was treated with N-ethyl-N-isopropylpropan-2-amine (51 mg, 397 μmol). The mixture was warmed to 86° C. and stirred for 14 hours, M+1=418. The mixture was then cooled to room temperature and concentrated in vacuo. The crude product was purified by column chromatography eluting with 10-30% EtOAc/hexane to give 35 mg of the title compound as a yellow oil. MS (m/z) 418 (M+H)+.
