caa a22 4500 378943944 CHVBK 20180305123659.0 cr unu---uuuuu 161128e20040101xx s 000 0 eng 10.1351/pac200476111953 doi (NATIONALLICENCE)gruyter-10.1351/pac200476111953 Pyridylketenes. Structure reactivity effects in nucleophilic and radical addition [Elektronische Daten] [A. D. Allen, A. V. Fedorov, K. Najafian, T. T. Tidwell, S. Vukovic] 2-, 3-, and 4-Pyridylketenes have been generated in CH3CN by photochemical Wolff rearrangements and identified by their ketenyl absorption in the infrared at 2127, 2125, and 2128 cm-1, respectively. Reaction of these pyridylketenes with n-BuNH2 results in the formation of intermediate amide enols from the 3- and 4-pyridylketenes, which are then converted to the corresponding pyridylacetamides. However , 2-pyridylketene forms a long-lived 1,2-dihydropyridine intermediate stabilized by an intramolecular hydrogen bond, and this is converted to the 2-pyridylacetamide with a rate constant 107 less than those for the conversion of the amide enols from the 3- and 4-pyridylketenes to amides. Hydration of the pyridylketenes results in the formation of an acid enol intermediate in the case of the 3-isomer, while the 2- and 4-isomers form longer-lived dihydropyridines. The pyridylketenes react with the stable free radical tetramethylpiperidinyloxyl (TEMPO,TO) forming 1,2-diaddition products ArCH(OT)CO2T. © 2013 Walter de Gruyter GmbH, Berlin/Boston Allen A. D. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut Fedorov A. V. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut Najafian K. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut Tidwell T. T. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut Vukovic S. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut Pure and Applied Chemistry De Gruyter 76/11(2004-01-01), 1953-1966 0033-4545 76:11<1953 2004 76 pac https://doi.org/10.1351/pac200476111953 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1351/pac200476111953 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Allen A. D. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut NATIONALLICENCE 700 1- Fedorov A. V. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut NATIONALLICENCE 700 1- Najafian K. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut NATIONALLICENCE 700 1- Tidwell T. T. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut NATIONALLICENCE 700 1- Vukovic S. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada aut NATIONALLICENCE 773 0- Pure and Applied Chemistry De Gruyter 76/11(2004-01-01), 1953-1966 0033-4545 76:11<1953 2004 76 pac CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter