title: An enantioselective ketene-imine cycloaddition method for synthesis of substituted ring-fused 2-pyridinones.
abstract: Previously, a method for the stereoselective synthesis of beta-lactams, starting from 2H-Delta(2)-thiazolines and Meldrum's acid derivatives, has been reported from our laboratory. We now report a new method for the synthesis of optically active, highly substituted ring-fused 2-pyridinones. This was discovered when 2-alkyl-Delta(2)-thiazolines and Meldrum's acid derivatives were treated with HCl(g) in benzene at 5 --> 78 degrees C. Further refinement of the synthetic protocol revealed that use of 1,2-dichloroethane as solvent at 0 --> 64 degrees C led to the desired 2-pyridinones in good yields and with excellent enantioselectivity. Use of these conditions allowed preparation of 2-pyridinones from several different Delta(2)-thiazolines and Meldrum's acid derivatives and may be a general route to 2-pyridinones.
authors.affiliation: Organic Chemistry, Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Emtenäs
authors.forename: L
authors.initials: L
authors.lastname: Alderin
authors.forename: F
authors.initials: F
authors.lastname: Almqvist
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis; D007769:Lactams / Q000138:chemical synthesis; D011084:Polycyclic Aromatic Hydrocarbons / Q000138:chemical synthesis; D011728:Pyridones / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D000900:Anti-Bacterial Agents; D007769:Lactams; D011084:Polycyclic Aromatic Hydrocarbons; D011728:Pyridones; C017679:2-hydroxypyridine