title: The Flögel-three-component reaction with dicarboxylic acids - an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives.
abstract: An extension of the substrate scope of the Flögel-three-component reaction of lithiated alkoxyallenes, nitriles and carboxylic acids is presented. The use of dicarboxylic acids allowed the preparation of symmetrical bis(β-ketoenamides) from simple starting materials in moderate yields. Cyclocondensations of these enamides to 4-hydroxypyridine derivatives or to functionalized pyrimidines efficiently provided symmetrically and unsymmetrically substituted fairly complex (hetero)aromatic compounds containing up to six conjugated aryl and hetaryl groups. In addition, subsequent functionalizations of the obtained heterocycles by palladium-catalyzed couplings or by oxidations are reported. We also describe the simple synthesis of a structurally interesting macrocyclic bispyrimidine derivative incorporating a 17-membered ring, whose configuration was elucidated by DFT calculations and by subsequent reactions.
authors.affiliation: Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany ; Department of Chemistry, Kamaun University, SSJ Campus Almora, Almora-263601, Uttarkhand, India.
authors.forename: Mrinal K
authors.initials: MK
authors.lastname: Bera
authors.affiliation: Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany.
authors.forename: Moisés
authors.initials: M
authors.lastname: Domínguez
authors.affiliation: Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Hommes
authors.affiliation: Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Reissig
keywords: DFT calculations; alkoxyallenes; condensations; multi-component reactions; olefin metathesis; pyridines; pyrimidines; β-ketoenamides