Regioselective synthesis of polysubstituted 3,3′-bi-1H-pyrazole derivatives via 1,3-dipolar cycloaddition reactions
作者:Ahmad M. Farag、Nabila A. Kheder、Milos Budesinsky
DOI:10.1016/s0040-4020(97)00583-8
日期:1997.7
add regioselectively to α-(benzothiazol-2-yl)cinnamonitriles 3 and α-(1-methylbenzimidazol-2-yl)cinnamonitriles 7 to yield exclusively the cycloadducts 5,5′-dicyano-4,4′,5,5′-tetrahydro[3,3′-bi-1H-pyrazoles] 4 and 8, respectively. Compounds 4 and 8 undergo aromatization via thermal elimination of hydrogen cyanide under basic conditions to afford the corresponding 3,3′-bi-1H-pyrazole derivatives 6 and
Synthesis of 3,3′-bi-1,2,4-Triazolo[4,5-a]- benzimidazole, 5,5′-bi-1,3,4-Thiadiazole, and Thiazolo[3,2-a]benzimidazole Derivatives
作者:Kamal M. Dawood、Mohamed A. Raslan、Ahmad M. Farag
DOI:10.1081/scc-120026349
日期:2003.12.1
Abstract A series of novel 3,3′-bi-1,2,4-triazolo[4,5-a]benzimidazole and thiazolo[3,2-a]-benzimidazole derivatives were synthesized via the reaction of bis-hydrazonoyl chlorides with 2-methylthiobenzimidazole and with benzimidazol-2-thiol, respectively. A direct synthesis of 5,5′-bi-1,3,4-thiadiazole and 4,5-bis-phenylhydrazono-2,3,4,5-tetrahydrothiazole derivatives is also described.
A Simple Method for the Synthesis of 2,3-Bis(arylazo)quinoxalines
作者:John K. Gallos、Ekaterini E. Corobili
DOI:10.1055/s-1989-27382
日期:——
The first synthesis of the novel 2,3-bis(arylazo)quinoxalines in high overall yields proceeds via reaction of 1,2-phenylenediamines with N,N′-diarylethanedihydrazonoyl dichlorides in the presence of triethylamine and oxidation of the resultant 2,3-bis(arylhydrazono)-1,2,3,4-tetrahydroquinoxalines.