Regioselective Synthesis of 1,3,5-Trisubstituted Pyrazoles
作者:Vidya G. Desai、Pooja C. Satardekar、Sampada Polo、Kashinath Dhumaskar
DOI:10.1080/00397911.2010.531492
日期:2012.3.15
Abstract A new and a simple approach toward synthesis of 1,3,5-trisubstitutedpyrazoles from chalcone arylhydrazones via oxidative cyclization has been achieved. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone was successfully used as an oxidizing agent to give excellent yields of pyrazoles. GRAPHICAL ABSTRACT
Synthesis of 1<i>H</i>-indazoles by an electrochemical radical C<sub>sp<sup>2</sup></sub>–H/N–H cyclization of arylhydrazones
作者:Hao Wan、Dongting Li、Huadan Xia、Liwen Yang、Hesham Alhumade、Hong Yi、Aiwen Lei
DOI:10.1039/d1cc04656j
日期:——
bond-forming reactions to N-heterocyclic frameworks has been a long-standing interest in organic synthesis. In this work, we develop an electrochemical radical Csp2–H/N–H cyclization of arylhydrazones to 1H-indazoles. The electrochemical anodic oxidation approach was adopted to synthesize a variety of 1H-indazole derivatives in moderate to good yields. HFIP was not only employed as a solvent or the proton donor
H<sub>2</sub>SO<sub>4</sub>O<sub>2</sub> AS AN EFFICIENT CATALYST FOR THE PREPARATION OF PHENYLHYDRAZONES AND 2,4-DINITROPHENYLHYDRAZONES UNDER SOLVENT-FREE CONDITIONS
作者:Ali Reza Kiasat、Foad Kazemi、Kazem Nourbakhsh
DOI:10.1080/10426500490422227
日期:2004.3.1
HSO mixed with silica gel (1:1) by weight produces a white powder which is an effective catalyst for the conversion of carbonyl compounds to their corresponding phenylhydrazones and 2,4-dintrophenylhydrazones under solvent-free conditions.
Catalytic Asymmetric 6π-Electrocyclization: Accessing Highly Substituted Optically Active 2-Pyrazolines via Diastereoselective Alkylations
作者:Benjamin List、Steffen Müller
DOI:10.1055/s-0029-1218792
日期:2010.7
The chiral phosphoric acid catalyzed asymmetric electrocyclization of α,β-unsaturated hydrazones has been studied. This reaction is one of the first catalyticasymmetric 6π-electrocyclizations reported, and enables the synthesis of 2-pyrazolines in high yields and enantiomeric ratios. The obtained products are not only interesting because of their pharmaceutical properties, but can be manipulated in
Catalytic enantioselective synthesis of 2-pyrazolines via one-pot condensation/6π-electrocyclization: 3,5-bis(pentafluorosulfanyl)-phenylthioureas as powerful hydrogen bond donors
作者:Moises A. Romero Reyes、Subhradeep Dutta、Minami Odagi、Chang Min、Daniel Seidel
DOI:10.1039/d4sc04760e
日期:——
A new conjugate-base-stabilized carboxylic acid (CBSCA) containing a 3,5-bis(pentafluorosulfanyl)phenylthiourea functionality catalyses challenging one-pot condensations/6π-electrocyclizations of hydrazines and α,β-unsaturated ketones under mild conditions. Structurally diverse N-aryl 2-pyrazolines are obtained in good yields and enantioselectivities. The superior performance of 3,5-bis(SF5)phenylthioureas