Synthesis of Trifluoromethyl-Containing Polysubstituted Aromatic Compounds by Diels-Alder Reaction of Ethyl 3-Benzamido-2-oxo-6-(trifluoromethyl)-2H-pyran-5-carboxylate
Eur. J. Org. Chem. 2015, 11, 2482-2491
Diels–Alder reactions of ethyl 3-benzamido-2-oxo-6-(trifluoromethyl)-2H-pyran-5-carboxylate (1a) with electronically different dienophiles, including cyclic enol ethers, cycloalkenes, α,β-unsaturated ketones, and terminal acetylenes, are useful for the efficient and selective three-step preparation of trifluoromethyl-containing aromatic compounds such as 3-aminobenzoic acid derivatives. We presume that the presence of the trifluoromethyl group is the main factor in determining the regioselectivity of the initial cycloaddition.