N,N-Dialkyl-N'-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XII.* Synthesis and Reactivity of the Pyrazolo[3,4-e][1,2,4]thiadiazine Ring System

Rebecca Norman, Michael Perkins, Andris Liepa, Craig Francis

    Research output: Contribution to journalArticlepeer-review

    4 Citations (Scopus)

    Abstract

    N,N-Dialkyl-N′-chlorosulfonyl chloroformamidines 1 reacted regioselectively with 1-substituted 5-aminopyrazoles 2 via a 1,3-CCN dinucleophilic substitution to afford pyrazolo[3,4-e][1,2,4]thiadiazines 3 as the sole isolated products. Compounds 3, representatives of a very rare ring system, were shown to possess three nucleophilic sites at N2, N4, and N6. Methylation occurred at all three sites. Alkylation with benzylic halides occurred preferentially at N2, but some also occurred at N4, and at C7a. Alkylation with ethyl bromoacetate occurred at both N4 and N6, but the latter derivatives underwent a pyrazole ring expansion to afford pyrimido[4,5-e][1,2,4]thiadiazine derivatives. Compounds 3 were unreactive towards various acylating agents.

    Original languageEnglish
    Pages (from-to)1455-1466
    Number of pages12
    JournalAustralian Journal of Chemistry
    Volume68
    Issue number9
    DOIs
    Publication statusPublished - 2015

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