Halogenated Pyridine Derivatives from Cycloaddition / Cycloreversion of Oxazinone and Haloalkyne Precursors
Elizabeth A Davis1, Megan S Hammett1, Jonathan R Scheerer1
1Department of Chemistry, William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187, United States.
Abstract:
This study explores the merged cycloaddition/cycloreversion of 1,4-oxazinone substrates with haloalkyne 2π reaction components. Haloalkynes proved generally competent in the Diels-Alder operation and exerted a small influence on the regioselection of the reaction sequence as compared to the reaction sequence with the derived terminal alkyne precursors. Following tandem cycloreversion and elimination of CO2, the haloalkynes showed a modest preference for formation of 4-halo pyridine products over 3-halo isomeric variants.
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