Potassium Hydroxide → 4,5-dimethyl-3,6-dihydro-2H-pyran-2,2-dicarboxylic acid
Reaction equation
[CH3:1][C:2]1[CH2:3][C:4]([C:14]([O:16]CC)=[O:15])([C:9]([O:11]CC)=[O:10])[O:5][CH2:6][C:7]=1[CH3:8].[OH-].[K+]>O1CCCC1>[CH3:1][C:2]1[CH2:3][C:4]([C:14]([OH:16])=[O:15])([C:9]([OH:11])=[O:10])[O:5][CH2:6][C:7]=1[CH3:8]Participants
4
Procedure
Part B. A solution of the ester compound prepared in Part A above (9.63 g, 37.6 mmol) in tetrahydrofuran (150 mL) was treated with an aqueous solution of potassium hydroxide (150 mL, 10N, 1.5 mol), and stirred vigorously at ambient temperature for 48 hours. The solid salt was collected by filtration, and neutralized by dissolving into 1N aqueous hydrochloric acid (200 mL). This was extracted with ethyl acetate (2×200 mL), and the extracts were combined, dried over anhydrous sodium sulfate, filtered and evaporated to afford the product, 3,6-dihydro-4,5-dimethyl-2H-pyran-2,2-dicarboxylic acid, as a waxy solid (7.46 g, 37.3 mmol, 99%). 1H NMR (CDCl3): δ 4.16 (2H, br s); 2.57 (2H, br s); 1.68 (3H, br s); 1.51 (3H, br s). Mass spectrum (NH3 -CI/DDIP): no M+H+ observed.