Synthesis of New -1,3,4-Thiadiazoles Substituted with Oxazepine and Benzoxazepine Moieties

Abstract

ABSTRACT2-amino-5-mercapto-1,3,4-thiadiazole 1 was introduced in condensation reaction with terephthaldehyde to yield bis-imine derivative 2. Compound 1 was also converted to the corresponding diazonium salt which was introduced in coupling reactions with alkaline solution of 2-hydroxybenzaldehyde and 4-hydroxybenzaldehyde as coupling reagents to give azo derivatives 4a and 4b containing aldehyde group, respectively. The resulting aldehydes 4a and 4b were then introduced in condensation reactions with 2-amino-5-mercapto-1,3,4-thiadiazole 1 to obtain the imines 5a and 5b respectively. The resulting imines 2, 5a and 5b were treated with both maleic and phthalic anhydrides, respectively, under (2+5) cycloaddition conditions afforded eight new bis-1,3,4-thiadiazoles substituted with 1,3-oxazepine and 1,3-benzoxazepine moieties (3a, 3b) and (6a-d)respectively. The new synthesized thiadiazoles have some biological, pharmaceutical and medicinal applications.

Synthesis and Characterization of New 1, 3, 4-Thiadiazoles Substituted with Imidazolidine Moiety

“…Thiadiazoles and their derivatives exhibit wide range of pharmacological activities such as antimicrobial activity (3) , antidepressant, cardiotonic (4) , antibacterial activity against Klebsiella pneumonia (5) , antitubercular (6,7) ,anticonvulsant (8) , antileshmanial , analgesic (9) ,antiinflammtory (10) , anticancer (11) , phosphodiesterase inhibitors (12) and effect on Tyrosinase enzyme (13) .This diversity of biological activity may be due to the presence of -N=C-S moity (14,15) . There are four isomers of thiadiazole , among these four isomers 1,3,4-thiadiazole is the most thermally stable; which is only isomer doesn´t contain any sulphur-nitrogen bond (16) . 1,3,4-thiadiazole relatively stable in aqueous acid solutions but the nucleus can undergo ring cleavage by aqueous base solutions (17) .…”