[C:1]([CH:4]1[CH2:8][CH:7]([CH3:9])[O:6][C:5]1=[O:10])(=O)[CH3:2].[OH-].[Na+].[CH:13]1(C=O)[CH2:18][CH2:17]C[CH2:15][CH2:14]1>C(OC(OCC)CC)C>[CH:2]1([CH:1]=[C:4]2[CH2:8][CH:7]([CH3:9])[O:6][C:5]2=[O:10])[CH2:17][CH2:18][CH2:13][CH2:14][CH2:15]1Example I was repeated using propionaldehyde diethyl acetal as the azeotroping solvent for the reaction to produce the α-alkylidene lactone. For this experiment 100 ml propionaldehyde diethyl acetal was charged to the reactor with 14.9 g (0.10 mole) 3-acetyl-5-methyldihydro-2(3H)-furanone. The mixture was stirred and 4 g (0.10 mole) powdered sodium hydroxide added. The mixture was allowed to stir for 10 minutes and then heated to reflux for 51/2 hours after which time 14.0 g (0.125 mole) cyclohexanecarboxaldehyde was added over a one-hour period. The mixture was heated under reflux for an additional twelve hours, cooled and worked up to recover 19 g crude 3-cyclohexylmethylene-5-methyldihydro-2(3H)-furanone (59% yield). The structure of the product was confirmed by proton and carbon nuclear magnetic resonance spectroscopy.
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