3044-70-0Relevant academic research and scientific papers
Reaction of pyrylium salts with nucleophiles. Part 25. Formation of pyridine-1-oxides, 2-isoxazolines and 1-pyrazoline-1-oxides
Uncuta, Cornelia,Caproiu, Miron Teodor,Campeanu, Valentin,Petride, Aurica,Danila, Mariana G.,Plaveti, Marieta,Balaban, Alexandru T.
, p. 9747 - 9764 (2007/10/03)
The reaction of tri- and tetrasubstituted pyrylium salts with hydroxylamine affords acyclic keto-ketoximes (to be described in a separate paper) which cyclize yielding pyridine-1-oxides and/or 2-isoxazolines. Both these classes of compounds, with many possible applications, can thus be obtained simply and in good yield. The regioselectivity of 2-isoxazoline formation from unsymetrically substituted pyrylium salts is discussed. An unprecedented minor product formed from 2,6-di-t-butyl-4-methylpyrylium perchlorate and two molecules of hydroxylamine is the corresponding 1- pyrazoline-1-oxide. Mechanistic rationalization of all products are provided.
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
