Heterotricyclic compounds, processes for their production and pharmaceutical compositions containing them.

摘要

A compound of the formula: wherein A1 is a single bond or a C1-C5 alkylene group bonding at the 2-, 2'- or 3-position, A2 is a C1-C3 alkylene group, A3 is a C1-C4 alkylene group, X is -O- or -SOn- and B is a carboxy group, a C2-C5 alkoxycarbonyl group, a cyano group, an amino group of the formula: or a carbamoyl group of the formula: which is useful as an antiviral agent with no side effect.