Synthesis of some thiochromeno[4,3-c]- and [3,4-c]-pyrazoles

Christopher D. Gabbutt, John D. Hepworth, B. Mark Heron, Simon J. Coles, Michael B. Hursthouse

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Reaction of 3-hydroxymethylene- and 3-cyanomethylene-thiochroman-4-ones with various hydrazine derivatives affords 4H-thiochromeno[4,3-c]pyrazoles. The novel isomeric thiochromeno[3,4-c]pyrazoles result when 4-(dimethylaminomethylene)thiochroman-3-ones react with methyl- and phenyl-hydrazines. Acidic hydrolysis of 3-(dimethylhydrazonoethylidene)-2,2,6-trimethylthiochroman-4-one yields the 3-cyanomethylene-thiochroman-4-one. Formation of 6-chloro-3-hydroxymethylenethiochroman-4-one is accompanied by a thiochroman-3-yl(oxothiochromen-3-yl)methane derivative produced through a rearrangement-carbocation interception sequence. A 3-isopropenylthiochromenone, obtained by the acid promoted rearrangement of a 3-hydroxymethylenethiochroman-4-one, undergoes Diels-Alder cycloadditions to provide a new route to thioxanthenones.

Original languageEnglish
Pages (from-to)2930-2938
Number of pages9
JournalJournal of the Chemical Society, Perkin Transactions 1
Issue number17
DOIs
Publication statusPublished - 1 Jan 2000
Externally publishedYes

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