Hydrochloric Acid → Methyl 6-Fluoro-3,4-dihydro-4-(methoxycarbonyl)-2H-benzopyran-4-butanoate

Beteiligte Stoffe

Reaktionsschritte

To a suspension of 8.81 g (0.183 mol) 50% NaH in 300 ml of DMF was added, dropwise, a solution of 27.5 g (0.131 mol) of methyl 6-fluoro-2,3-dihydro-4H-benzopyran-4-carboxylate in 100 ml of DMF. After stirring at room temperature for 1 hour, a solution of 33 g (0.183 mol) of methyl 4-bromobutyrate in 25 ml of DMF was added. The resultant homogeneous solution was stirred at room temperature for 16 hours and then poured onto ice/H2O and acidified to pH 3.0 with concentrated HCl. The aqueous was extracted twice with CH2Cl2 and the combined extracts were dried (NaSO4) and filtered. The filtrate was evaporated in vacuo to an oil (44 g) which was purified by column chromatography on 2 Kg of silica gel, eluting with CH2Cl2 /Et2O. Yield 12 g (30%), an oil; NMR (CDCl3) (delta) 1.5-2 6(m, 8H, CH2), 3.62 (s, 3H, CH3), 3.66 (s, 3H, CH3), 4.21 (t, 2H, J=6 Hz, CH2), 6.7-7.4 (m, 3H, arom).

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