title: Sequential amination/annulation/aromatization reaction of carbonyl compounds and propargylamine: a new one-pot approach to functionalized pyridines.
abstract: A general one-pot synthesis of pyridines 4a-t from the reaction of dialkyl acyclic/cyclic ketones 1a-i, methyl, aryl/heteroaryl ketones 1m-r, and aldehydes bearing alpha-hydrogens 1s,t with propargylamine 2 is described. Gold and copper salts are efficient catalysts for the reaction of ketones with 2. The formation of the pyridines 4 is suggested to proceed through the sequential amination of carbonyl compounds followed by regioselective 6-endo-dig cyclization of the N-propargylenamine (N-propargyldienamine) intermediate 3(5) and aromatization reaction. Whereas the preparation of linear polycyclic pyridine 4i can be carried out by reacting cholestan-3-one 1i with 2, the angular polycyclic pyridine 4j has been obtained starting from cholest-5-en-3-one 1j. Selectivity of the reaction of polycyclic dicarbonyls 1k,l with 2 has also been investigated.
authors.affiliation: Istituto di Chimica Organica Alessandro Marchesini, Facoltà di Farmacia, Università degli Studi di Milano, Via Venezian, 21, 20133 Milano, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Abbiati
authors.forename: Antonio
authors.initials: A
authors.lastname: Arcadi
authors.forename: Gabriele
authors.initials: G
authors.lastname: Bianchi
authors.forename: Sabrina
authors.initials: S
authors.lastname: Di Giuseppe
authors.forename: Fabio
authors.initials: F
authors.lastname: Marinelli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Rossi