On the Fluorescence Reaction of Pharmaceutically Important o‐Aminobenzamides and o‐Aminobenzenesulfonamides with Phthalaldehyde and Analogues

Abstract

SummaryIn order to develop a specific TLC-fluorescence detection, drugs such a s Quinethazone (la), Fenquizone (lb), Diazoxide (7), Bendroflumethiazide (lla), Hydrochlorothiazide (llb) and their derivatives were hydrolysed to provide o-arninobenzamide 2 and o-aminobenzenesulfonamides 8,12, and 13. The reaction of these 1,5-N-bisnucleophiles with phthalaldehyde (3a) and analogues 3b-e resulted in weak up to intensive fluorescent products 5,9,14, 15. Applying this method to Diazoxide capsules, 5 ng of Diazoxide (7) could be detected by pre-and postchromatographic derivatisation with 3-benzoylpyridine-2-carbaldehyde (3e) on TLC plates. The reaction of o-aminobenzenesulfonamide 8 with 3,4-dimethoxyphthalaldehyde (3b) in CD30D/DCl provided a monodeuterated compound lob. N,N-Acetals 17,18, and 19 were obtained from the reaction of furan-3.4-dicarbaldehyde (16) with o-aminobenzenesulfonamides 8,12, and 13 in MeOW20 "C.