78019-00-8Relevant academic research and scientific papers
Route to Highly Substituted Pyridines
Hilf, Justin A.,Holzwarth, Michael S.,Rychnovsky, Scott D.
, p. 10376 - 10382 (2016)
Pyridine rings are common structural motifs found in a number of biologically active compounds, including some top-selling pharmaceuticals. We have developed a new approach to access substituted pyridines. The method aims to provide a reliable synthesis of a diverse range of substituted pyridines through a three-step procedure. Readily available enones are first converted into 1,5-dicarbonyls through a two-step Hosomi-Sakurai allylation/oxidative cleavage sequence, which is followed by subsequent cyclization to the corresponding pyridine using hydroxylamine hydrochloride. A variety of substituted pyridines have been synthesized using this method.
4-HO-TEMPO-Catalyzed Redox Annulation of Cyclopropanols with Oxime Acetates toward Pyridine Derivatives
Zhan, Jun-Long,Wu, Meng-Wei,Wei, Dian,Wei, Bang-Yi,Jiang, Yu,Yu, Wei,Han, Bing
, p. 4179 - 4188 (2019/05/01)
A 4-HO-TEMPO-catalyzed redox strategy for the synthesis of pyridines through the annulation of cyclopropanols and oxime acetates has been developed. This protocol features good functional group tolerance and high chemoselectivity and also promises to be efficient for the late-stage functionalization of skeletons of drugs and natural products. Mechanism studies indicate that the reaction involves the in situ generated α,β-unsaturated ketones and imines as the key intermediates, which are derived from cyclopropanols and oxime acetates via a TEMPO/TEMPOH redox cycle, respectively. The pyridine products are formed as a result of annulation of enones with imines followed by TEMPO-catalyzed oxidative aromatization by excess oxime acetates. This method not only realizes the TEMPO-catalyzed redox reaction but also broadens the frontiers for TEMPO in catalysis.
Kinetics and Mechanisms of Nucleophilic Displacements with Heterocycles as Leaving Groups. 2. N-Benzylpyridinium Cations: Rate Variation with Steric Effects in the Leaving Group
Katritzky, Alan R.,El-Mowafy, Azzahra M.,Musumarra, Giuseppe,Sakizadeh, Kumars,Sana-Ullah, Choudhry,et al.
, p. 3823 - 3830 (2007/10/02)
N-Benzyl groups are transferred to piperidine from pyridinium ions by unimolecular SN1 and/or bimolecular SN2 mechanisms.Steric acceleration by α-phenyl groups is reduced by an adjacent β-methyl group but increased by constraining th
