Hoffmann-La Roche Inc.

Miyako Kamata

Nobuo Shimma

Tatsuo Ohtsuka

Kazuteru Yokose

Masahiro Aoki

The invention is concerned with tricyclic compounds of the formula ##STR1## wherein R.sup.1 is a hydrogen atom or a carboxy-protecting radical; R.sup.2 is a hydrogen atom or a lower alkyl radical which may be substituted with a halogen atom; R.sup.3 and R.sup.4 independently are a hydrogen atom or a lower alkyl radical which may be substituted with a hydroxy radical or a substituted or unsubstituted amino radical; X is a halogen atom; and R.sup.5 and R.sup.6 are independently a hydrogen atom or a lower alkyl radical which may be substituted with a hydroxy radical, a lower alkoxy radical or a substituted or unsubstituted amino radical; or R.sup.5 and R.sup.6, taken together with the adjacent nitrogen atom, may form a 5 to 7 membered heterocyclic ring which may be substituted with one or more substituents at the carbon atom(s), and the heterocyclic ring may further contain --NR.sup.7 --, --O--, --S--, --SO--, --SO.sub.2 -- or --NR.sup.7 --CO--, and also R.sup.7 is a hydrogen atom, a lower alkenyl radical, a lower alkyl or aralkyl radical which may be substituted, or a radical represented by the formula

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Chigasaki, Japan

Miyako Kamata