Facile One-Pot Transformation of Primary Alcohols into 3-Aryl- and 3-Alkyl-isoxazoles and -pyrazoles
作者:Eiji Kobayashi、Hideo Togo
DOI:10.1055/s-0039-1690102
日期:2019.10
Abstract Various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylisoxazoles in good yields in one pot by successive treatment with PhI(OAc)2 in the presence of TEMPO, NH2OH, and then NCS, followed by reaction with alkynes in the presence of Et3N. Similarly, various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylpyrazoles in good yields in one pot by successive
novel efficient tandem reaction of hydrazones and α-bromo ketones is reported for the preparation of 1,3,5-trisubstituted pyrazoles by visible light catalysis. In this system, the monosubstituted hydrazones show wonderful reaction activity with alkyl radicals, generated from α-bromo ketones. A radical addition followed by intramolecular cyclization affords the important pyrazole skeleton in good to
The AlCl3-promoted reactions of cycloalkanones with hydrazones are described. This approach represents a mild and operationally simple method to access 2,3-diaryl-4,5,6,7-tetrahydro-1H-indazoles and their analogues in good to moderate yields.
cyclization protocol employing cobalt nitrate and 1,2‐dichloroethane to produce substituted 1H‐1,2,4‐triazoles. Notably, 1,2‐dichloroethane serves both the solvent and a hydrogen source for transfer hydrogenation. This methodology works under mild conditions, providing a direct approach for the synthesis of 1H‐1,2,4‐triazoles.
Lewis acid–catalyzed green synthesis and biological studies of pyrrolo[3,4‐<i>c</i>]pyrazoles in aqueous medium
作者:Manpreet Kaur、Baldev Singh、Anania Arjuna
DOI:10.1002/jhet.3740
日期:2020.1
An environmentallybenign approach in aqueous medium by means of Lewisacid catalyst affords a wide spectrum of pyrazoline derivatives in satisfactory yields. [3+2] cycloadditionreactions of substituted azomethine‐N‐imines to maleimide in aqueous medium at relatively high concentrations of Lewisacid catalyst have emerged as an environment friendly alternative to conventional solvents. Promising catalytic