Diethyl Oxalate → 4-(4-Chromanone-3-yl)-2,4-dioxobutyric acid

Participants

Reaction Steps

Solid 3-acetyl-4-chromanone (0.570 g, 3 mmoles, described in Example 5) is added in portions at room temperature to a suspension of 57% sodium hydride (0.379 g, 9 mmoles) in dry tetrahydrofuran (10 ml). The mixture is heated within 15 min to 60° C and diethyl oxalate (0.438 g, 3 mmoles) in tetrahydrofuran (10 ml) is added. After heating at reflux temperature under an atmosphere of nitrogen for 17 hr., the solvent is removed under reduced pressure, the residue is dissolved in ice-water and extracted with ether. The aqueous phase is acidified with 6N hydrochloric acid and extracted with chloroform. The organic phase is dried, evaporated, and the residue crystallized from methanol-chloroform to give 4-(4-chromanone-3-yl)-2,4-dioxobutyric acid (Vl; R1, R2, R3, Rl4 and R5 = H, and X = O), νmaxnujol 1705, 1615 and 1560 cm-1.

Provenance & Evidence