1,1-diethoxybut-2-ene as a precursor of (2-hydroxyethyl)-substituted alkoxy dienes: convenient intermediates for a new synthesis of 2-substituted and 2, 6-disubstituted tetrahydro-4H-pyran-4-ones

3-ethoxyhexa-3,5-dien-1-ol is prepared from a reaction between an electrophile, ethylene oxide and an alpha-metalated alkoxy diene which involves an epoxide ring opening. Synthesis of 2- and 2,6-disubstituted tetrahydro-4H-pyran-4-ones involves these alpha-substituted alkoxy dienes as intermediates. Propylene oxide yields a mixture of cis and trans compounds. 1H NMR and gas chromatography analyses are employed to calculate the cis-trans ratio.