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.