PRODUCTION OF TETRAHYDROFURYL CARBAMATE DERIVATIVE

PROBLEM TO BE SOLVED: To simply obtain, through an industrially profitable process, the above compound having HIV protease inhibitory activity by using a compound of 4-aminobenzene sulfonic acid having an amino group without protection. SOLUTION: This tetrahydrofurylcarbamate derivative of formula II is obtained by carrying out the reaction of tetrahydrofurylcarbamate of formula I [the conformation of (R) marked C is R conformation and the conformation of (S) marked C is S conformation] with a reactive functional derivative or its salt of 4-aminobenzene sulfonic acid. The tetrahydrofurylcarbamate derivative of formula I is obtained by carrying out the reaction of a sulfonate derivative of formula III (A is methyl, phenyl, 4-methoxyphenyl, 4-methylphenyl or 2- nitrophenyl) with isobutylamine or the reaction of an epoxy derivative of formula IV with isobutylamine.