Dihydropyridine-Based Multicomponent Reactions. Efficient Entry into New Tetrahydroquinoline Systems through Lewis Acid-Catalyzed Formal [4 + 2] Cycloadditions
作者:Rodolfo Lavilla、M. Carmen Bernabeu、Inés Carranco、José Luis Díaz
DOI:10.1021/ol027545d
日期:2003.3.1
tetrahydroquinolines in a stereoselective manner through a Lewis acid-catalyzed formal [4 + 2] cycloaddition. InCl(3) and Sc(OTf)(3) are the catalysts of choice for this process. The in situ generation of a reactive 1,4-dihydropyridine through the regioselective nucleophilic addition of cyanide to pyridiniumsalts allows a one-pot four-component transformation.
Berberine chloride (1) upon treatment with NaOAc-Ac2O yields naphthalene derivatives 4 and 5 In like fashion, 8 gives naphthalene 10; isoquinoline methiodide leads to β-naphthyl acetate; and 12 provides 14. The reaction has been extended to the 3-carbonyl pyridinium series where 3-acetylpyridine methiodide and 3-pyridinecarboxaldehyde methiodide furnish lactones 16 and 17, respectively. All these transformations
Substituent effect on the reverse Menschutkin reaction of 1-methylpyridinium cations with iodide anion can be described in terms of the LArSR equation with ϱ=3.60 which provides evidence against very late transition state of the nitrogen-to-iodine transmethylation.
Excellent correlation between substituent constants and pyridinium N-methyl chemical shifts
作者:Sha Huang、Jesse C.S. Wong、Adam K.C. Leung、Yee Man Chan、Lili Wong、Myrien R. Fernendez、Amanda K. Miller、Weiming Wu
DOI:10.1016/j.tetlet.2009.06.081
日期:2009.9
Substituents on the pyridinium ring of N-methylpyridinium derivatives, especially those on the 2- or 4-position, have a large effect on the 1H and 13C NMR chemical shifts of the N-methyl group. Reasonable correlations between the chemical shift changes and the resonance substituentconstants are observed. The dual substituent parameter approach provides an excellent correlation when a combination of
Pyridinium salts—versatile reagents for the regioselective synthesis of functionalized thiazocino[2,3-b]indoles by tandem dinucleophilic reactions of thiooxindoles
作者:Mostafa Kiamehr、Firouz Matloubi Moghaddam、Pavel V. Gormay、Volodymyr Semeniuchenko、Alexander Villinger、Peter Langer、Viktor O. Iaroshenko
DOI:10.1016/j.tet.2012.09.059
日期:2012.11
The reaction of thiooxindoles with various 2- and 3-substituted pyridinium salts afforded a variety of functionalized thiazocinoindoles. The products have been prepared in good to excellent yields by regioselective dinucleophilic C/S-cyclocondensation of thiooxindoles with pyridinium salts.