| 摘要 |
PROBLEM TO BE SOLVED: To economically obtain a dihydropyran derivative in high productivity and yield by reacting aldehydes with a diene compound in the presence of a Lewis acid catalyst and a specific cocatalyst. SOLUTION: An aldehyde of the formula, R<1> -CHO (R<1> is H, 1-12C alkyl, 6-12C aryl or the like which may be substituted with an alkyl) is reacted with a diene compound of formula I (R<2> and R<3> are each H, a 1-6C alkyl or alkenyl) in the presence of a Lewis acid catalyst and a cocatalyst without any solvent or in a solvent at -30 to 100 deg.C to provide the objective 5,6-dihydro-2H-pyran derivative of formula II. A compound (excluding a nitro compound) having weaker coordination force to Lewis acid than the aldehyde and having action dissolving the Lewis acid into a solvent by coordinating to Lewis acid is used as the cocatalyst and, e.g. one or two or more kinds of compounds selected from aliphatic or aromatic esters, chloroacetic esters, ethers, ketones and carbonates are used in an amount of 0.1-10 mol based on 1 mol Lewis acid. |
