Pyridazines and their Benzo Derivatives

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

“…As a result, the Hünig's base/DMPU system often became the conditions of choice in the synthesis of fused ring systems from dichlorides 1 Predominant formation of pyridazo[3,2-c][1,2,4,6]thiatriazine dioxides 33 resulting from bonding of the ring nitrogen of the aminopyridazine to the amidine carbon atom of 1 and the exocyclic amino group reacting with the sulfamoyl chloride moiety is consistent with the known greater nucleophilicty of ring nitrogen N-2 compared to the exocyclic amino group of 3-aminopyridazines. [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.…”

General approach for regioselective synthesis of fused phosphono substituted-oxadiazines

“…The synthesis of phosphono substituted-oxadiazines, which are practically unknown, should be of great interest, because organophosphorus com- pounds often possess antibiotic, antineoplastic, antibacterial, or antiviral attributes [6]. In connection with a previous communication [7], we report on the reactions of tetraethyl 1,3-dithietane-2,4-diylidenebis(cyanomethylphosphonate) (1), easily obtained (in high yield, ca. 70%) by the method developed by Neidlein and Eichinger [8], with several substituted-␣-carbonylmonohydrazones, yielding mainly fused oxadiazines.…”

“…For instance, many pyridazines are in clinical use [1,2], while many thiadiazines exhibit antiprotozoal, antiviral, bactericidal, and fungicidal properties [3,4], probably by virtue of the presence of the toxopheric (-N‫ס‬C-S) grouping. The oxygen analog, namely oxadiazines, on the other hand, are very few in the published literature [5].…”

Synthesis of enantiomerically pure, partly saturated (RS)-[(1S)-isoborneol-10-sulfinyl]-substituted [1,2,4]triazolo[1,2-a]pyridazine, cinnolines and benzo[f]cinnolines

“…In general, pyridazine derivatives constitute a class of compounds with a wide spectrum of biological activities. 7 In azafagomines, 6 potent inhibitors of various glycosidases, and in cinnolines, 7,8 exhibiting various pharmacological properties, the presence of two neighbouring nitrogen atoms exerts determining effects on structural and electronic properties, and on the bioactivity of such compounds. Scaffold relationship of azafagomines and cinnolines with cycloadducts 3 and 4 renders the DA reaction of sulfinylsubstituted dienes 1 with PTDA a smooth and diastereo-selective route for the preparation of analogues of those bioactive compounds.…”