[CH3:1][O:2][C:3](=[C:6]([CH3:8])[CH3:7])[CH2:4][CH3:5].[CH2:9]([O:11]C(C(C)C)=CC)[CH3:10].[CH:18](C=C)=O.C1(C=CC(O)=CC=1)O>>[CH3:1][O:2][C:3]1([CH2:4][CH3:5])[C:6]([CH3:18])([CH3:8])[CH2:7][CH:10]=[CH:9][O:11]154 g of a mixture of 3-methoxy-4-methyl-3-pentene (I, with R = CH3) and 3-methoxy-4-methyl-2-pentene (II, with R = CH3), which according to the nuclear resonance spectrum comprises about 95% of I and about 5% of II, 32 g of acrolein and 1 g of hydroquinone are heated at 165° C. for 20 hours. Distillation of the reaction mixture gives 58 g of the desired 2-methoxy-2-ethyl-3,3-dimethyl-2,3-dihydro-4H-pyran of boiling point 64° - 67° C./13 mm Hg. This corresponds to a yield of 72% of theory.
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