Thieno[3,2-b]benzofuran and benzothiophene derivatives useful as optical
申请人:Sandoz Ltd.
公开号:US04526976A1
公开(公告)日:1985-07-02
Compounds of formula I ##STR1## in which X is O or S; Y is O, S or NR.sub.3 where R.sub.3 is hydrogen or C.sub.1-4 alkyl (preferably methyl or ethyl) and rings A and B may be further substituted by non-chromophoric substituents.