Synthesis and Tautomeric Structure of 2-arylazo-4H-imidazo[2,1-b][1,3,4]thiadiazines

Abstract

Two series of the title compounds were prepared via reaction of N-aryl 2-oxohydrazonoyl halides with 1-amino-4-phenylimidazoline-2-thione. Their tautomeric structure was elucidated by spectral analysis, and the correlation of their acid dissociation constants with the Hammett equation, to be as the hydrazone form.

Synthesis of a new triheterocycle. Bis-pyrazolo[1,5-a][4',3'-e]pyrimidine

“…Such an absorption pattern is similar to that of typical azo chromophore. 1 Furthermore, the electronic absorption spectra of compound 1 in solvents of different polarities showed little, if any, shift (Table 1). On the basis of the foregoing data, compound 1 was assigned the indicated azo tautomeric structure 1 (Scheme 1) in both solid and solution phases.…”

“…In continuation of our studies dealing with the utility of hydrazonoyl halides for synthesis of various heterocyclic ring systems, [1][2][3][4][5][6][7][8][9][10][11] we wish to report herein a new facile synthesis of bispyrazolo [1,5-a][4',3'-e]pyrimidine ring system and its various functionalized derivatives that have not been reported hitherto. The earlier methods reported for synthesis of such ring system are multisteps.…”

Reactions of hydrazonoyl halides with heterocyclic thiones. Convenient methodology for heteroannulation, synthesis of spiroheterocycles and heterocyclic ring transformation

“…6). 17 This finding indicates that the initially formed thiohydrazonates undergo in situ dehydrative cyclization as soon as they are formed to give 18 as end products. …”

Synthesis of new pentaheterocyclic ring system as antiandrogene, anti HCV and anti H1N1 agents

“…[1][2][3][4][5] Coumarine is an important structural moiety present in a variety of natural and synthetic products that possess significant biological activities, 6 such as, anticoagulants, antifungal, antineoplastic, antibacterial, spasmolytic or cytotoxic activity. [7][8][9] In addition, chitosan, the naturally occurring polysaccharide, can be used as heterogeneous phase transfer catalyst in heterocyclic synthesis, 10 as well as transition metal support for the preparation of heterogeneous catalysts.…”