| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject compound useful as an intermediate for pharmaceuticals, etc., on an industrial scale at a low cost in high efficiency by reacting a simple aldehyde with a Danishefsky-type diene in the presence of a specific catalyst. SOLUTION: The objective compound of formula II (preferably an optically active 2-methyl-2,3-dihydro-4H-pyran-4-one, etc.) is produced by subjecting (A) an aldehyde of formula R<1> CHO [R<1> is a (substituted) 1-15C alkyl, a (substituted) 2-15C alkenyl, a (substituted) 2-15C alkynyl or a (substituted) 6-14C aryl] (preferably acetaldehyde) and (B) a butane derivative of formula I (R<2> to R<4> are each a (substituted) 1-15C alkyl or a (substituted) 6-14C aryl; R<5> is a (substituted) 1-15C alkyl or a (substituted) 6-14C aryl] (preferably 4-methoxy-2- trimethylsiloxybutadiene) to asymmetric hetero Diels-Alder reaction in the presence of a chiral Lewis acid and treating the reaction product with a protonic acid. |
