7,8-dihydro-5H-cyclohepta[b]pyridine-5,9(6H)-dione

7,8-dihydro-5H-cyclohepta[b]pyridine-5,9(6H)-dione is an organic intermediate, which can be prepared from dimethyl 2,3-pyridine dicarboxylate and dimethyl glutarate by two-step reaction.

To a solution of dimethyl 2,3-pyridinedicarboxylate (750 g, 3.84 mol) and dimethyl glutarate (935 g, 5.84 mol) in toluene (5.25 L) was added potassium tert-butanolate (1.0 M in THF, 9.6 L, 9.6 mol), maintaining an internal temperature of <30°C. The reaction mixture was heated to 55- 60C and kept for 1 hr. The reaction mixture was concentrated under vacuum to <7 L and then cooled to 0-5C. To the concentrated reaction mixture, n-heptane (11.3 L) was added, followed by ice water (10.9 L), maintaining an internal temperature of <5°C. The pH of the reaction mixture was then adjusted to 6.0-6.5 with glacial acetic acid (435 ml) at 0-5C. The resulting slurry was filtered and the cake was washed successively with water (2.3 L) and n-heptane (3.7 L) and then dried under vacuum at 50-55°C to afford dimethyl 5,9-dihydroxy-7H-cyclohepta[b]pyridine-6,8-dicarboxylate. White solid, yield 822 g, 73%.