Synthesis of Bioactive Heterocycles: Aza-Claisen Rearrangement of 4-N-(4"-Aryloxybut-2"-ynyl),N- methylamino[1]benzothiopyran-2-ones

Abstract

The hitherto unreported 4-(aryloxymethylene-1-methyl-1,2,3-trihydropyrido[3,2-c]benzothiopyran-5-ones are synthesized in 60-90% yield by the thermal aza-Claisen rearrangement of 4-N-(4"-aryloxybut-2"-ynyl),N-methylamino[1]benzothiopyran-2-ones in refluxing 1,2-dichlorobenzene. 4-N-(4"-Aryloxybut-2"-ynyl),N-methylamino[1]benzothiopyran-2-ones were prepared in 80-90% yields by the reaction of 4-chloro[1]benzothiopyan-2-one and appropriate 1-aryloxy-N-methylaminobut-2-ynes in refluxing ethanol. 4-Chloro[1]benzothiopyran-2-ones was in turn synthesised from 4-hydroxythiocoumarin by reaction with phosphorous oxychloride at 140 °C.

aza-Claisen rearrangement - sigmatropic rearrangement - heterocycles - pyrido[3,2-c][1]benzothiopyran-5-ones - 4-chlorothiocoumarin - 4-hydroxythiocoumarin

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