Silver(I)-Catalyzed Domino Cyclization/Cyclopropanation/Ring-Cleavage/Nucleophilic Substitution Reaction of Enynones with Enamines: Synthesis of 4-(Furan-2-yl)-3,4-dihydro-2H-pyrrol-2-one

Abstract

We report the synthesis of 4-(furan-2-yl)-3,4-dihydro-2H-pyrrol-2-one derivatives. In this approach, two core structures, the furan ring and 3,4-dihydro-2H-pyrrol-2-one, are constructed via silver­(I)-catalyzed cascade cyclization/cyclopropanation/ring-cleavage/nucleophilic substitution reaction of enynones with enamines. A reasonable mechanism has been proposed. This method possesses some advantages such as high chemoselectivity, mild reaction conditions, simple operation, and short reaction time.

Silver(I)-Catalyzed Tandem Reaction of Enynones and 4-Alkenyl Isoxazoles: Synthesis of 2-(Furan-2-yl)-1,2-dihydropyridines

“…On the other hand, the reaction involving metal carbene is attractive due to its high reactivity. , For example, the construction of furan ring starting from enynone as a metal carbene precursor, − the cyclopropanation of alkenes via (2-furyl)­carbene complexes (Scheme a), 8f‑8g and the non-atom-economic construction of 1,4-dihydropyridine ring via the reaction of diazo compounds as a metal carbene precursor with isoxazole have been disclosed (Scheme b) . Recently, our group has reported silver­(I)-catalyzed tandem reaction of enynones with 4-alkynyl isoxazoles (Scheme c) .…”

“…Recently, our group has reported silver­(I)-catalyzed tandem reaction of enynones with 4-alkynyl isoxazoles (Scheme c) . As part of our continuous interest in employing enynone as the precursor of (2-furyl)­carbene, , also inspired by Davies’ construction of 1,4-dihydropyridine frame via the reaction of diazo compounds with isoxazole, a protocol for synthesizing 2-furyl-1,2-dihydropyridine derivatives by treating 4-alkenyl isoxazole with enynone as a (2-furyl)­carbene precursor seems to be direct and efficient (Scheme d). We herein report our original results.…”

A ligand-enabled, copper(ii)-catalyzed, highly selective and efficient synthesis of 2E-alkenylfurans from ynenones

“…Ynenones have been reported for the synthesis of furan derivatives 4 in the presence of transition-metal catalysts such as gold, palladium, silver, rhodium, and copper. [5][6][7][8][9][10] Most of the reported reactions have been proposed to proceed after carbene insertion or dimerization of α-furyl metal carbene intermediates, during which an air-free environment is required (Scheme 1A). Moreover, the in situ-generated α-furyl carbene complexes A from ynenones can be oxidized readily to 2-acyl furan 9b,10c in an air atmosphere, and even an alkyl group can be installed at the end of an alkyne (Scheme 1A).…”

Ketone Derivatives of Propargylamines as Synthetic Equivalents of Conjugated 2,4,1-Enynones in the Synthesis of Acetylenic 2-Pyrazolines and Pyrazoles

“…Conjugated enynones are applied successfully as substrates in the synthesis of various functional derivatives of oxygen-, − nitrogen-, − and sulfur-containing , heterocycles. This can be attributed to the high reactivity of the conjugated π-system and chemical diversity of their reaction centers, as well as the possibility of the presence of enynones in the form of three isomers with different relative positions of multiple bonds (conjugated 2,4,1-, 1,4,3-, and 4,2,1-enynones and 2-methylenebut-3-yn-1-ones). − − …”