Boron trifluoride etherate → HCID 69517239, compound

Participants

Reaction Steps

Ethyl 7-hydroxy-2-(trifluoromethyl)-2H-chromene-3-carboxylate from Example 1a, Step 1 (2.0 g, 6.94 mmole) was treated with t-butyl trichloroacetaimidate in cyclohexane at room temperature. After addition of a catalytic amount of boron trifluoride etherate (139 uL), the mixture (orange solid precipitated) was stirred at room temperature overnight. Solid sodium bicarbonate (2.33 g, 27.76 mmole) was added into the mixture. The mixture was passed through the silica plug and was washed with 6% ethyl acetate in hexane. The filtrate containing the product was evaporated to give yellow oil (1.34 g, 56%) having >90% purity: LCMS m/z 367.00 (M+Na). 1H NMR (CDCl3/400 MHz) 7.70 (s, 1H), 7.12 (m, 1H), 6.63 (s, 1H), 6.61 (m, 1H), 5.68 (q, 1H, J=7.2 Hz), 4.30 (q, 2H, J=7.2 Hz), 1.33 (t, 3H, J=7.2 Hz). This ester was of suitable purity to use without further purification.

Provenance & Evidence