Diethyl Malonate → 7-Benzyl-4-hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b]pyridine-5-carboxylic acid ethyl ester

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Reaction Conditions

Reaction Steps

Diethyl malonate (2.14 mL, 0.014 mol) was added slowly to a suspension of sodium hydride (60% dispersion in mineral oil, 0.66 g, 0.017 mol) in 50 mL anhydrous DMF stirred at 0° C. under argon. The solution was stirred for 15 minutes. Solid 1-benzyl-1H-thieno[2,3-d][1,3]oxazine-2,4-dione (58) (3.58 g, 0.014 mol) was added, and the solution was heated at 110° C. for 2 hours. The solvent was then removed under vacuum, and the residue was dissolved in water and washed with ethyl acetate. The aqueous layer was acidified with dil. HCl to precipitate the product, which was collected by vacuum filtration to give 3.09 g (68%) of 7-benzyl-4-hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b]pyrdine-5-carboxylic acid ethyl ester. MP 146° C. 1H-NMR (DMSO-d6) δ 1.30 (t, J=7.2 Hz, 3H), 4.32 (q, J=7.2 Hz, 2H), 5.25 (s, 2H), 7.24-7.36 (m, 7H), 13.21 (b, 1H) ppm; EIMS m/z 330 (M+1).

Provenance & Evidence