title: Tandem vicarious nucleophilic substitution of hydrogen/intramolecular Diels-Alder reaction of 1,2,4-triazines into functionalized cycloalkenopyridines.
abstract: Synthesis of 2,3- and 3,4-cyclopentenopyridines, 5,6,7,8-tetrahydroquinolines and 5,6,7,8-tetrahydroisoquinolines from 1,2,4-triazine derivatives is reported. Introduction of an alpha-functionalized methyl substituent (e.g. arylsulphonyl, sulphonamide, sulphonic acid ester) into position 3- or 6- of triazines by vicarious nucleophilic substitution of hydrogen and subsequent alkylation with alkyl iodides bearing an acetylenic function in terminal position afforded valuable intermediates for intramolecular Diels-Alder reaction with inverse electron demand. When heated at higher temperature, these triazine derivatives gave the Diels-Alder cycloadducts, which, after spontaneous extrusion of nitrogen moiety, led to a variety of functionalized cycloalkenopyridine derivatives.
authors.affiliation: Institute of Chemistry, University of Podlasie, Siedlce, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Branowska
authors.forename: Stanisław
authors.initials: S
authors.lastname: Ostrowski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Rykowski
mesh_terms: D000478:Alkylation; D006859:Hydrogen / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D014227:Triazines / Q000737:chemistry*
chemical_list: D011725:Pyridines; D014227:Triazines; C093444:1,2,4-triazine; D006859:Hydrogen