N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. III. Pyrido- and Pyridazo-Fused [1,2,4,6]Thiatriazine Dioxides

Abstract

N,N-Dialkyl-N′-chlorosulfonylchloroformamidines 1 reacted with 2-aminopyridines 2 to give novel pyrido[1,2-b][1,2,4,6]thiatriazine dioxides 3 and pyrido[2,1-c][1,2,4,6]thiatriazine dioxides 4. Reaction of 1 with 3-aminopyridazines 5 afforded pyridazo[3,2-c][1,2,4,6]thiatriazine dioxides 6 and a pyridazo[2,3-b][1,2,4,6]thiatriazine dioxide 7. The compounds 6 and 7 are derivatives of new ring systems.

New heteroatom-rich ring systems from N,N-dialkyl-N’-chlorosulfonyl chloroformamidines

“…An overview of the types of ring systems produced from these unusual + C=N-S + building blocks is presented in Scheme 59. Dichlorides 1 have been shown to react with 1,2-dinucleophilic species to give new fivemembered ring products 26 or with various 1,3-dinucleophilic species to provide a variety of novel or very rare fused [1,2,4,6]thiatriazines, 33,37,42,43 31,65 and [1,2,4]thiadiazines. 67 Similar reactions of dichlorides 1 with 1,4-dinucleophiles afforded new seven-membered ring products.…”

“…Reaction of 1 with an excess of 2-aminopyridines 29 Table 8). 37 Carrying out the reaction with a slight excess of the dichloride 1 in DMF in the presence of Hünig's base resulted in the production of significant amounts of both isomeric products 30 and 31 with a slightly greater proportion of 31. Compounds 30 and 31 are new derivatives of very rare ring systems.…”

“…[38][39][40][41] Our observations are that the chloro-substituted amidine carbon atom of 1 is the more electrophilic site in response to nitrogenous nucleophiles. 37 In addition to the interest inherent in the chemical attributes of the novel fused [1,2,4,6]thiatriazine products described above, testing for possible biological activity seemed appropriate. In the absence of reactive NH moieties (amenable to substitution reactions) in these ring systems, opportunities for structural variations were limited.…”

“…These observations led to the presumption that compound 34b exists as two conformers that interconvert very slowly (on the NMR timescale). 37 Variable temperature 500 MHz 1 H NMR studies of a solution of 34b in DMSO-d 6 were undertaken in an attempt to clarify this presumption. However, the twin resonance phenomenon persisted at higher temperatures (up to 105 ºC) while further heating to 125 ºC and beyond caused chemical change.…”

“…Unequivocal determination of structures was based on X-ray crystallographic analysis of representative compound 33e. 37 The relatively low solubility of compounds 33 allowed selective precipitation directly from the reaction mixture, simply achieved by the addition of ethyl acetate and water to the vigorously stirred reaction mixture. The product often precipitated and settled out at the interface between the organic and aqueous phases.…”