Biaolin Yin

A novel entry to functionalized benzofurans and indoles via palladium(0)-catalyzed arylative dearomatization of furans.

A novel entry to functionalized benzofurans and indoles from furans in moderate to good yields has been developed. This protocol involves palladium(0)-catalyzed dearomatizing intramolecular arylation of the furan ring, formation of a π-allylic palladium complex, furan ring opening, and a β-hydride elimination sequence.

Facile synthesis of 3a,6a-dihydro-furo[2,3-b]furans and polysubstituted furans involving dearomatization of furan ring via electrocyclic ring-closure.

A facile and atom-economic method for the synthesis of 3a,6a-dihydro-furo[2,3-b]furan derivatives and polysubstituted furans starting from furylcarbionls has been developed. This protocol involved a domino Claisen rearrangement/dearomatizing electrocyclic ring-closure/aromatizing electrocyclic ring-opening sequence.

Practical access to spiroacetal enol ethers via nucleophilic dearomatization of 2-furylmethylenepalladium halides generated by Pd-catalyzed coupling of furfural tosylhydrazones with aryl halides

Pd-catalyzed cross-coupling of furfural tosylhydrazones with aryl halides produces 2-furylmethylenepalladium halides, which can undergo intramolecular nucleophilic dearomatization to provide spiroacetal enol ethers. This is the first report on the formation of 2-furylmethylenepalladium halides from stable furfural hydrazones instead of from 2-furylmethyl halides, which are not readily accessible or are unstable.

Cu(II)-Promoted Transformations of α-Thienylcarbinols into Spirothienooxindoles: Regioselective Halogenation of Dienyl Sulfethers Containing Electron-Rich Aryl Rings

Under the promotion of Cu(II) salts, the α-thienylcarbinols with an N-phenyl carbonyl group at the other α-position are converted into three different ranges of spirothienooxindoles involving dearomatizing Friedel-Crafts reaction. In addition, the unprecedented regioselective CuX(2)-mediated C-H functionalization/halogenation of dienyl sulfether containing electron-rich aryl rings is presented.

Synthesis of Spiro-lactams and Polysubstituted Pyrroles via Ceric Ammonium Nitrate-Mediated Oxidative Cyclization of N-Furan-2-ylmethyl-β-Enaminones

Spiro-lactams and polysubstituted pyrroles were synthesized by reactions of furfurylamines with ynones followed by oxidation. Specifically, the protocol involved in situ generation of N-furan-2-ylmethyl-β-enaminones and their subsequent oxidation by ceric ammonium nitrate (6 equiv for spiro-lactam formation, 3 equiv for pyrrole formation). This useful dearomatizing oxidation, which likely proceeds via a free-radical pathway, can be expected to extend the synthetic applications of furan and pyrrole derivatives.

Base-Mediated Decomposition of Amide-Substituted Furfuryl Tosylhydrazones: Synthesis and Cytotoxic Activities of Enynyl-Ketoamides

Base-mediated decomposition of amide-substituted furfuryl tosylhydrazones afforded practical access to novel multifunctionalized enynyl-ketoamides. In addition, furfuryl tosylhydrazones with stable furan rings underwent an interesting tosyl-group migration to form sulfones, which have potential synthetic applications. Some of the obtained enynyl-ketoamides demonstrated good cytotoxicities against human tumor cell lines.

2,5-Oxyarylation of Furans: Synthesis of Spiroacetals via Palladium-Catalyzed Aerobic Oxidative Coupling of Boronic Acids with α-Hydroxyalkylfurans.

A protocol for the 2,5-oxyarylation of furan rings via Pd-catalyzed aerobic oxidative coupling of boronic acids with α-hydroxyalkylfurans is reported. This protocol provides rapid, green access to diverse biologically interesting and synthetically useful unsaturated spiroacetals from sustainable furan derivatives.

Highly Facialselective Synthesis of Pyranose 1,3-Oxazines and Their Ring Opening with Nucleophiles: A Novel Entry to 2-C-Branched Glycosides

A TMSOTf-promoted cycloaddition of N-benzoyl-N,O-acetals with various glycals and 3-deoxy glycals affords pyranose 1,3-oxazines with high facial selectivity. In addition, a highly diastereoselective ring opening of the resulting pyranose 1,3-oxazines is reported. With diverse nucleophiles, these reactions take place upon heating at 80 °C. This novel ring-opening reaction affords structurally diversified 2-C-branched glycosides with three newly formed contiguous stereocenters.

Selective Pd-catalyzed α- and β-arylations of the furan rings of (ortho-bromophenyl)furan-2-yl-methanones: C(CO)–C bond cleavage with a furan ring as a leaving group and synthesis of furan-derived fluorenones

Selective palladium diacetate-catalyzed α- and β-arylations of the furan rings of (ortho-bromophenyl)furan-2-yl-methanones 1 under two different conditions are reported. In the presence of potassium tert-butoxide as a strong base and triphenylphosphine as a ligand, methanones 1 undergo α-arylation accompanied by C(CO)–C bond cleavage. In contrast, in the presence of potassium carbonate as the base and tricyclohexylphosphonium tetrafluoroborate as the ligand, methanones 1 undergo intramolecular β-arylation to afford furan-derived fluorenones in high yields from a wide variety of substrates. In addition, a one-pot protocol for the successive direct intramolecular β-arylation and intermolecular α-arylation of the furan rings of 1 has been achieved.

Synthesis of N,O-Spiroacetals and α-Arylfurans via Pd-Catalyzed Aerobic Oxidative 2,5-Aminoarylation and α-Arylation of N-[3-(2-Furanyl)propyl]-p-Toluenesulfonamides with Boronic Acids.

Unsaturated N, O-spiroacetals and α-arylfurans were synthesized via palladium-catalyzed aerobic oxidative coupling reactions between N-[3-(2-furanyl)propyl]- p-toluenesulfonamides and boronic acids, with KF and KOAc as the respective additives. These reactions involve an unprecedented dearomatizing 2,5-aminoarylation and a direct α-arylation of furan rings, respectively, with O2 as the terminal oxidant.