摘要:
Recently discovered 4-trifluoromethyl-1,3-oxazin-6-ones react with electron-poor dienophiles as 2-aza-1,3-dienes in Diels-Alder cycloadditions to give new 2-trifluoromethyl pyridines (3a-d, 4a-c). Regioselectivity is excellent in the case of unsymmetrical dienophiles. These new pyridines permit further useful transformations.