Yoshitomi Pharmaceutical Industries, Ltd.

Kiyoteru Ikegami

Kazuhiro Goto

Kazumi Saeki

Tomohiko Munakata

A heterocyclic compound of the formula: ##STR1## or a pharmaceutically acceptable acid addition salt thereof, wherein R.sup.1 is hydrogen, C.sub.1-4 alkyl, C.sub.1-4 alkoxycarbonyl, formyl, nitroso, acyl, phenacyl, aralkyl, .alpha.-(benzyloxycarbonyl)benzyl or .alpha.-carboxybenzyl; each of R.sup.2 and R.sup.3 is hydrogen, C.sub.1-4 alkyl or aryl; and all of R.sup.4, R.sup.5 and R.sup.6 are hydrogens, or both R.sup.1 and R.sup.6, and R.sup.4 and R.sup.5 together form single bonds; in which definitions the term 'acyl', 'phenacyl', 'aralkyl' or 'aryl' means that it may be substituted by at least one substituent at any position(s) on the aromatic nucleus, each substituent being independently selected from C.sub.1-4 alkyl, C.sub.1-4 alkoxy, halogen, hydroxyl, phenyl, nitro, trifluoromethyl, methylthio, methanesulfonyl and methylenedioxy. Such compounds are useful as drugs for treating immune diseases.

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Yoshio, Japan

Kiyoteru Ikegami