An Easy and Convenient Synthesis of 2-Furan-2-ylacetamides by Sequential Palladium-Catalyzed Oxidative Aminocarbonylation of (<i>Z</i>)-2-En-4-yn-1-ols/Conjugate Addition/Aromatization
A simple and convenient synthesis of 2-furan-2-ylacet-amides 4 starting from readily available (Z)-2-en-4-yn-1-ols 1 is reported. The method is based on a PdI 2 -catalyzed oxidative aminocarbonylation of the triple bond of 1 to give the corresponding 2-ynamide intermediates 2, which undergo intramolecular conjugate addition to give 2-(5H-furan-2-ylidene)acetamide derivatives 3. Spontaneous or one-pot
Alkynols undergo palladium-catalyzed aminocarbonylation leading to the direct formation of different heterocyclic derivatives, depending on the position of the OH group with respect to the triple bond. In the cases of 4-yn-1-ols and (Z)-2-en-4-yn-1-ols, the initially formed 2-ynamide intermediates, respectively, undergo cyclization leading to tetrahydrofuran derivatives or 2-furan-2-ylacetamides, respectively. In the case of 2-yn-1-ols, the aminocarbonylation products undergo intermolecular conjugate addition, followed by lactonization, leading to aminofuranones.