Synthesis of new -1,3,4-thiadiazoles substituted with oxazepine and benzoxazepine moieties

Abstract

2-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.