Synthesis of Furans via Rhodium(III)-Catalyzed Cyclization of Acrylic Acids with α-Diazocarbonyl Compounds

Abstract

An efficient protocol for the synthesis of furans through Rh­(III)-catalyzed vinyl C–H activation from acrylic acids and α-diazocarbonyl compounds has been developed. The reaction features broad functional group tolerance and affords a series of furans in moderate to good yields. Moreover, no additives such as copper or silver salts are required. Some control experiments are performed to give insight into the mechanism of this cascade transformation and the decarbonylation process is involved in the formation of the furan product.

Ruthenium-Catalyzed Chemo-Selective Carbene Insertion into C–H Bond of Styrene over Cyclopropanation: C–C Bond Formation

“…We have proposed here the plausible reaction mechanism (Figure ) based on the known literature reports and computational studies for the formation of the product ( 3 ). Initially, the active catalyst Cp*Ru­(III)­Cl 2 ( I ) would coordinate with the CC bond of olefin to generate intermediate ( II ), which is transformed to intermediate ( III ) via TS-I and subsequent elimination of HCl molecule.…”

DFT Study on Mechanism of Ni–Al Bimetallic-Catalyzed C–H Cyclization to Construct Tricyclic Imidazoles: Roles of NHC Ligand and AlMe3

“…Tricyclic imidazoles and their 7-membered ring derivatives, as one of the most important classes of structural motifs, − are widely present in numerous biologically active material molecules. Owing to their significance, the synthesis of tricyclic imidazoles and their 7-membered ring derivatives − has attracted widespread attention, and extensive effort has been devoted to the development of new methodologies. − Among a large number of strategies, direct construction of a 7-membered ring via C7–H cyclization of benzimidazoles with alkenes would provide a more straightforward, atom- and step-economic access to tricyclic imidazoles from more easily accessible substrates. However, over the past few decades, transition metal-catalyzed C–H cyclization − for medium-ring synthesis has been a challenging goal.…”

Electrocatalytic [3 + 2] Annulation for the Synthesis of Polysubstituted Furans

“…Among them, classical Paal–Knorr and Feist–Bénary reactions via 1,4-dicarbonyl cyclocondensation represent the most well-known approaches under strong acid or basic conditions. Cyclization of allenyl/alkynyl alcohol or ketone derivatives was proven to be a powerful method for the synthesis of densely functionalized furans. , A plethora of transition-metal-mediated carbenoid annulation strategies have also been elaborately designed to access polysubstituted furans . Regardless of the great progresses that have been made, these methodologies require the prefunctionalization of corresponding substrates, which would substantially reduce the total synthesis efficiency; thus, pursuing a step-economic route remains an ongoing and urgent task in organic synthesis.…”