Preparation of 4-(Nitromethyl)furan Derivatives and Their Application in the Syntheses of Bis(furan-2-yl)oximes

Abstract

An efficient method for the preparation of tetrasubstituted furans, which contains a nitromethyl group at the 4-position, has been developed. The applications of 4-(nitromethyl)­furans on the synthesis of highly functionalized bis­(furyl)­oxime were explored for the first time.

Controllable Access to Diazo-functionalized 2-Methylene-2,3-dihydrofurans and Diazo-functionalized Furans from Enynones and Diazo Carbonyl Compounds

“…In the AgSbF 6 /DBU system, anions I starting from compounds 2 in the presence of DBU undergo Michael addition to enynones 1 , , providing racemic intermediates II . Intermediates IV are formed via 5- exo -dig cyclization of intermediates III , in which Ag­(I) coordinates with a CC triple bond .…”

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.…”