SYNTHESIS OF POLYFUSED THIENO(2,3-b)THIOPHENES PART 1: SYNTHESIS OF THIENOPYRIMIDINE DERIVATIVES

Abstract

3,4-Diamino-2,5-dicarbethoxythieno(2.3-b)thiophene 1 reacted with malononitrile or ethyl cyanoacetate to afford bis(thienopyrimidin-4-one) derivatives 2_a.b The reaction of compound 1 with o-aminothiophenol, o-aminophenol or o-phenylenediamine gave benzothiazolyl-, benzoxazolyl-, benzoimidazolylthienothiophene 3_a-c, Chloroacetylation of compound 1 and reacting the resulting compound 4 with malononitrile furnished thienopyrolopyrimidine 6. Fusion of compound 1 with formamide yielded bis(thienopyrimidine) 7 which reacted with POCI₃/PCl₅ to yield the corresponding chloro derivative 8 which was converted into the corresponding hydrazine derivative 9. Treatment of compound 1 with CS₂, NaOH and 1,2 dibromoethane produced the corresponding 1.3 dithiolane 11 which also treated with chloroacetyl chloride or ethyl mercaptoacetate to get the corresponding β-lactame 12 or thiazolidinone 13. On reacting compound 1 with CS₂, NaOH and (CH₃)₂S0₄ produced the corresponding bi(dithiocarbamate methyl ester) 14 which treated with hydrazine hydrate to yield the corresponding bis(thienopyrimidine) derivative 15. This compound reacted with Lawesson's reagent (LR) to give the desired compounds 16 and 17. While its reaction with (CH₃)₂ SO₄ and NaOH furnished the corresponding methyl derivative 18. Fusion of compound 18 with aniline afforded compound 19. Compound 19 was allowed to react with ethyl acetoacetate, acetylacetone, α-oxoketene dithioacetal, ethoxymethylene malononitrile or LR to get the described compounds 2O_a.b-24 respectively.