DIPEA (0.931 mL, 5.35 mmol) was added to a mixture of ethyl 7-trifluoromethyl-4-hydroxy-2-oxo-2′,3′,5′,6′-tetrahydro-spiro[naphthalene-1,4′-pyran]-3-carboxylate (1.32 g, 3.56 mmol) and glycine tert-butyl ester hydrochloride (0.717 g, 4.28 mmol) in dioxane (30 mL). The reaction mixture was stirred at 75° C. for 17 hours. The reaction mixture was cooled to room temperature and concentrated in vacuo to give a yellow solid. The crude solid was suspended in ether and filtered to give the desired compound as a light yellow solid (1.29 g). MS (m/e)=456.2 (M+H)+.
