| abstract |
A compound of the formula (2a) <IMAGE> (2a) in which Ar1 is 2-sulfophenyl, 3-sulfophenyl, 4-sulfophenyl, 2,5-disulfophenyl, 3-sulfo-4-aminophenyl, 4-sulfo-3-aminophenyl, 3-methoxy-5-sulfophenyl, 3-sulfo-4-methylphenyl, 3-sulfo-4-methoxyphenyl, 2,5-disulfo-4-methylphenyl, 2,5-disulfo-4-methoxyphenyl, 2,5-disulfo-4-aminophenyl, 5,7-disulfo-naphth-2-yl, 4,8-disulfo-naphth-2-yl, 3,6,8-trisulfo-napth-2-yl, 4,6,8-trisulfo-naphth-2-yl, 8-sulfonaphth-1-yl, 6-sulfo-naphth-1-yl or 7-sulfo-naphth-1-yl. |