PURPOSE: To readily produce the subject compound useful as an antibiotic by subjecting a compound which is produced from two kinds of specific compounds to a ring-closing reaction under heating in a solvent.
CONSTITUTION: A compound of formula I [A is four to seven-membered heterocyclic group containing O, S, NR4 (R4 is H, imino-protecting group, etc.,) in the group; R1 is lower alkyl, alkynyl, etc., which may have a substituent; R2 is H, carboxyl-protecting group] is reacted with a compound of formula: R(R8) 3 (R8 is alkoxy, aryloxy, etc.,) in a solvent-free state or in an aprotic solvent at 30 to 150°C for 2-20hrs, and the acid adduct by-produced is evaporated away under vacuum. The left compound of formula II is subjected to a ring-closing reaction in a solvent such as toluene at 100-170°C for 2-30hrs, followed by distilling away the solvent and further subjecting the product to a crystallization process, etc., to provide the objective compound of formula III.
TANAKA TERUO
MORI MAKOTO
KAWAMOTO ISAO
