title: A very efficient cerium(IV) ammonium nitrate catalyzed, four-component synthesis of tetrahydropyridines and its application in the concise generation of functionalized homoquinolizine frameworks.
abstract: Molecular diversity: A cerium(IV) ammonium nitrate (CAN) catalyzed, four-component reaction from very simple acyclic starting materials afforded densely substituted tetrahydropyridines, which were transformed into homoquinolizines by using a gamma-alkylation-ring-closing metathesis (RCM) sequence (see scheme).The cerium(IV) ammonium nitrate (CAN) catalyzed, four-component reaction between primary aliphatic amines, beta-ketoesters or beta-ketothioesters, alpha,beta-unsaturated aldehydes, and alcohols provided a very efficient and atom-economical access to substituted 6-alkoxy-2-methyl-1,4,5,6-tetrahydropyridines. These materials were then transformed into homoquinolizine derivatives in excellent yields by using a two-step sequence comprised of regioselective gamma-deprotonation-allylation and ring-closing metathesis reactions. The possibility of displacing the alkoxy group by allylsilane nucleophiles, presumably through a vinylogous acyliminium intermediate species, was also demonstrated.
authors.affiliation: Departmento de Química Orgánica y Farmacéutica Universidad Complutense, Facultad de Farmacia, Plaza de Ramón y Cajal, Spain.
authors.forename: Vellaisamy
authors.initials: V
authors.lastname: Sridharan
authors.forename: Swarupananda
authors.initials: S
authors.lastname: Maiti
authors.forename: J Carlos
authors.initials: JC
authors.lastname: Menéndez
mesh_terms: D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D011807:Quinolizines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D009566:Nitrates; D011725:Pyridines; D011807:Quinolizines; C532772:cerium(IV) ammonium nitrate; D002563:Cerium; C006568:ammonium nitrate