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N,N-Dialkyl-N’-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XIV. Synthesis and Reactivity of the New Benzo[4,5]imidazo[1,2-b][1,2,6]thiadiazine ring system.
N,N-Dialkyl-N’-chlorosulfonyl chloroformamidines 1 underwent regioselective reactions with the 1,3 NCC bis nucleophilic 1H benzimidazole-2-acetonitriles 4 and related compounds to produce benzo[4,5]imidazo[1,2 b][1,2,6]thiadiazine dioxides 6, 9, 12 and 14; representatives of a new ring system. Reaction of dichlorides 1 with trifluoroacetyl derivative 16 afforded benzo[4,5]imidazo[1,2 c]pyrimidines 19 and 20. An N-acyl and some N-alkyl derivatives of benzimidazo-thiadiazines 6 were prepared to demonstrate the potential of this new ring system as a novel scaffold for synthetic and medicinal chemistry applications. Treatment of the 4-cyano-5 methyl-benzimidazo-thiadiazine 26c with LiAlH4 resulted in an unexpected and remarkable conversion of the nitrile to give the 4,5 dimethyl-benzimidazo-thiadiazine 29.
CH17255 Accepted 15 August 2017
© CSIRO 2017