title: Microwave assisted synthesis and unusual coupling of some novel pyrido[3,2-f][1,4]thiazepines.
abstract: 3-Amino-3-thioxopropanamide (1) reacted with ethyl acetoacetate to form 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide (2), which reacted with α-haloketones 3 to produce 2,3-disubstituted-8-hydroxy-6-methyl-2H,5H-pyrido[3,2-f]-[1,4]thiazepin-5-ones 4a-c. Benzoylation of 4c led to the formation of the dibenzoate derivative 9. Compounds 4a-c could be prepared stepwise through the formation of S-alkylated derivatives 10a-c. Compounds 2, 4a-c, 9 and 10a-c were prepared using microwave as a source of heat, and gave better yields in shorter times than those achieved by traditional methods. Coupling of 4a-c with arenediazonium chlorides proceeded unusually to give the 6-hydroxy-4-methyl-2-(arylazo)thieno[2,3-b]pyridin-3(2H)-one ring contraction products 14. Structures of the newly synthesized compounds were proven by spectral and chemical methods.
authors.affiliation: Department of Chemistry, Faculty of Science, Cairo University, Egypt.
authors.forename: Rasha M
authors.initials: RM
authors.lastname: Faty
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Youssef
authors.forename: Ayman M S
authors.initials: AM
authors.lastname: Youssef
mesh_terms: D008872:Microwaves; D013841:Thiazepines / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D013841:Thiazepines