A Convenient Synthesis of Dithieno[2,3-b] [2,3-h]Quinolines and Pyrimido [4',5':4,5]Thieno [2,3-b]Thieno[2,3-h]Quinolines

摘要

6,7-Dihydrobenz[b]thiophen-4(5H)one (1) was condensed with 4- chlorobenzaldehyde to yield the benzylidene derivative 2 which underwent Michael addition reacting with cyanothioacetamide in methanolic sodium methoxide solution to give the thienoquinoline 3. Compound 3 was reacted with #alpha#- halo compounds to obtain the substituted thio intermediates 4a-f, which upon treatment with sodium ethoxide produce the dithienoquionline derivatives 5a-f. Thienopyrimidothienoquinoline e.g. 9 was obtained from the reaction of o- aminocarboxamide derivative 5d with triethyl orthoformate.