title: Highly regio- and stereoselective Diels-Alder cycloadditions via two-step and multicomponent reactions promoted by infrared irradiation under solvent-free conditions.
abstract: Infrared irradiation promoted the Diels-Alder cycloadditions of exo-2-oxazolidinone dienes 1-3 with the Knoevenagel adducts 4-6, as dienophiles, leading to the synthesis of new 3,5-diphenyltetrahydrobenzo[d]oxazol-2-one derivatives (7, 9, 11 and 13-17), under solvent-free conditions. These cycloadditions were performed with good regio- and stereoselectivity, favoring the para-endo cycloadducts. We also evaluated the one-pot three-component reaction of active methylene compounds 20, benzaldehydes 21 and exo-2-oxazolidinone diene 2 under the same reaction conditions. A cascade Knoevenagel condensation/Diels-Alder cycloaddition reaction was observed, resulting in the final adducts 13-16 in similar yields. These procedures are environmentally benign, because no solvent and no catalyst were employed in these processes. The regioselectivity of these reactions was rationalized by Frontier Molecular Orbital (FMO) calculations.
authors.affiliation: Department of Organic Chemistry, National School of Biological Sciences, National Polytechnic Institute, Prol. Carpio y Plan de Ayala, S/N, 11340 Mexico, D. F., Mexico.
authors.forename: Maria Ines
authors.initials: MI
authors.lastname: Flores-Conde
authors.affiliation: Department of Organic Chemistry, National School of Biological Sciences, National Polytechnic Institute, Prol. Carpio y Plan de Ayala, S/N, 11340 Mexico, D. F., Mexico.
authors.forename: Leonor
authors.initials: L
authors.lastname: Reyes
authors.affiliation: Institute of Chemical-Biology Research, University of Michoacan of San Nicolás de Hidalgo, Edif. B-1, Ciudad Universitaria, Francisco J. Mujica S/N, 58066 Morelia, Mich, Mexico.
authors.forename: Rafael
authors.initials: R
authors.lastname: Herrera
authors.affiliation: Department of Chemical Sciences, Graduate School of Cuautitlán-National University of Mexico, Campo 1, Avenida 1ro. de Mayo S/N, Cuautitlán Izcalli, Estado de México 54740, Mexico.
authors.forename: Hulme
authors.initials: H
authors.lastname: Rios
authors.affiliation: Department of Chemistry, University of Guanajuato, Noria Alta, S/N, Guanajuato Gto. 36050, Mexico.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Vazquez
authors.affiliation: Department of Chemical Sciences, Graduate School of Cuautitlán-National University of Mexico, Campo 1, Avenida 1ro. de Mayo S/N, Cuautitlán Izcalli, Estado de México 54740, Mexico.
authors.forename: Rene
authors.initials: R
authors.lastname: Miranda
authors.affiliation: Department of Organic Chemistry, National School of Biological Sciences, National Polytechnic Institute, Prol. Carpio y Plan de Ayala, S/N, 11340 Mexico, D. F., Mexico.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Tamariz
authors.affiliation: Department of Organic Chemistry, National School of Biological Sciences, National Polytechnic Institute, Prol. Carpio y Plan de Ayala, S/N, 11340 Mexico, D. F., Mexico.
authors.forename: Francisco
authors.initials: F
authors.lastname: Delgado
mesh_terms: D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction / Q000379:methods*; D007259:Infrared Rays; D008968:Molecular Conformation; D011090:Polyenes / Q000737:chemistry; D011522:Protons; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D011090:Polyenes; D011522:Protons; D012997:Solvents