PRODUCTION METHOD OF 8-CYCLOPENTYL-6-ETHYL-3-(SUBSTITUTED)-5,8- DIHYDRO-4H-1,2,3a,7,8-PENTAZA-as-INDACENE, AND INTERMEDIATE USEFUL THEREFOR

摘要

PURPOSE: Provided is a production method of 8-cyclopentyl-6-ethyl-3-(substituted)-5,8- dihydro-4H-1,2,3a,7,8-pentaza-as-indacene by a method easily applicable and having less problems and excellent economical practicability, and an intermediate useful therefor. The compound is useful for the therapy of asthma or the like. CONSTITUTION: The production method of a compound of formula(5) comprises: heating a mixture produced by solventless reaction of gamma-caprolactone with p-methoxybenzylamine; reducing the thus obtained compound of formula(1) followed by acylating the thus reduced compound with ethyloxalyl chloride; oxidizing the thus produced compound of formula(2) followed by cyclizing the oxidized compound; O-methylating the thus obtained compound of formula(3); treating the thus produced 3-methoxy-pyridinone compound with cyclopentylhydrazine; removing a p-methoxybenzyl group from the thus produced pyrazolopyridinone compound; esterifying the thus produced lactam compound; then treating the thus produced imino ester (imidate) compound with a compound of formula(4) (R1 is H or the like).