Diels-Alder Reaction of 2-(Cyclic Amino)-Substituted 3-Furancarbonitriles with Maleimides to Phthalimides

An efficient Diels-Alder reaction is described in the furan series, leading to phthalimides in high yields. Thermal treatment of 2-(4-morpholinyl, 1-piperidinyl, and 1-pyrrolidinyl)-3-furancarbonitriles with maleimide derivatives, e.g. maleimide, N-methylmaleimide, N-benzylmaleimide, N-phenylmaleimide and N-(4-nitrophenyl)maleimide, in boiling acetic acid caused a [4 + 2] cycloaddition reaction to give the corresponding phthalimide derivatives.