Transition metal-catalyzed domino reactions have been used as powerful tools for the preparation of polysubstituted furans in a one-pot manner. In this paper, an efficient synthetic method was developed for the construction of tri-or tetrasubstituted furans from electron-deficient alkynes and 2-yn-1-ols by a silver-catalyzed domino reaction. It is especially noteworthy that a 2,3,5-trisubstituted 4-ynylfuran was formally obtained in an extremely direct manner without tedious stepwise synthesis. In addition, regio-isomeric furans were observed when substituted aryl alkynyl ketones were employed. This methodology represents a highly efficient synthetic route to electron-deficient furans for which catalytic approaches are scarce. The reaction proceeds efficiently under mild conditions with commercially available catalysts and materials.
Highly functionalized multisubstituted 1,4-dihydropyridines 5 have been concisely synthesized in moderate to good yields via L-proline-catalyzed one-pot multicomponent reactions (MCRs) of alkynoates or alkynones 1, amines 2, beta-dicarbonyl compounds 3 and aldehydes 4 under mild conditions. The MCR process involves hydroamination/Knoevenagel condensation/Michael-type addition/intramolecular cyclization processes and leads to the formation of 1,4-dihydropyridines 5. The molecular structure of 5ckaa was confirmed by single-crystal X-ray diffraction. This method is energy saving and environmentally friendly, providing easy access to diverse multisubstituted polyfunctional 1,4-dihydropyridines.
Polysubstituted Furans. -A wide range of tri-or tetra-substituted furans is obtained by tandem base-catalyzed etherification-Ag-catalyzed cyclization reaction of alkynes with propargylic alcohols. Interestingly, the cyclization of phenylethynylcarboxylate (IV) proceeds with excellent regioselectivity, while a mixture of regioisomers is formed from arylethynyl aryl ketones (VI). -(CAO, H.; JIANG*, H.; MAI, R.; ZHU, S.; QI, C.; Adv.
L-Proline-Catalyzed Synthesis of Highly Functionalized Multisubstituted 1,4-Dihydropyridines. -Under optimized conditions, alkynones, primary amines, β-dicarbonyl compounds and aldehydes are converted via multicomponent domino reactions in one pot into the dihydropyridines. The inexpensive non-toxic solvent and catalyst, and reactions at room temperature are notable advantages of the method. -(JIANG*, H.; MAI, R.; CAO, H.; ZHU, Q.; LIU, X.; Org.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.