Synthesis and Rhodium(II)-Mediated Cascade Cyclopropanation/Rearrangement/Isomerization of Diazo 2,3,5-Trisubstituted Furans: The Construction of Penta-substituted Aromatic Compounds

Abstract

Ag(I)-catalyzed synthesis of diazo-trisubstituted furans starting from diazo-cumulated allenyl ketones has been investigated. The Rh 2 (OAc) 4 -catalyzed reaction of the diazo 2,3,5-trisubstituted furans provided penta-substituted aromatics via cascade intermolecular cyclopropanation/rearrangement/isomerization. The cyclopropanation on the furan ring/rearrangement of cyclopropane moiety has been reported. A reasonable mechanism is proposed.

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

“…Since synthetic applications of analogues for compounds 4 have been explored, we focused on studying those of compounds 3 , containing a diazo group. We looked forward to reactions such as Wolff rearrangement, C–H insertion, and cyclopropanation based on metal carbene from a diazo group.…”

“…Few methods for their preparation and synthetic application have been disclosed. For instance, the synthesis of naphthalene [1,2- b ] furans via C–H insertion of furan containing a diazo group (Scheme c) and the construction of penta-substituted aromatic compounds via cyclopropanation/rearrangement/isomerization of diazo 2,3,5-trisubstituted furans have been developed (Scheme d) . Overall, investigation of their synthesis and application is lacking, and it has become a considerable challenge.…”

“…For instance, the synthesis of naphthalene [1,2-b] furans via C−H insertion of furan containing a diazo group (Scheme 1c) 6 and the construction of penta-substituted aromatic compounds via cyclopropanation/rearrangement/isomerization of diazo 2,3,5-trisubstituted furans have been developed (Scheme 1d). 7 Overall, investigation of their synthesis and application is lacking, and it has become a considerable challenge. Our protocol on the exploration is to use available enynones and diazo carbonyl compounds as materials (Scheme 1e).…”

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

“…1,2-Dihydropyridine and furan scaffolds are widely present in bioactive molecules and natural products and have also been widely applied as a synthetic block. − Therefore, 1,2-dihydropyridine bearing a furyl group at 2-position (i.e., 2-furyl-1,2-dihydropyridine), which is a novel linked bis-heterocyclics, is an important structural skeleton based on potential among biological activities and synthetic applications. Many exciting achievements on the individual construction of 1,2-dihydropyridine and furan , framework have been made; however, these methodologies involved are usually non-atom-economic routes.…”

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

“…Nitromethylfurans are important organic synthetic intermediates, owing to two motifs of a furan ring and a nitro group. The former has been widely applied in the synthesis of natural products, complex molecules, and pharmaceuticals . For the latter, many conversions of a nitro group into another N -containing group, such as amino, oxime, cyano, etc., have been achieved .…”