Yi-Feng Qiu

Palladium-Catalyzed/Norbornene-Mediated ortho-Amination/N-Tosylhydrazone Insertion Reaction: An Approach to the Synthesis of ortho-Aminated Vinylarenes

ortho-Aminated vinylarene derivatives were obtained via a reaction of aryl iodides, N-benzoyloxyamines, and N-tosylhydrazones. This approach involves a palladium-catalyzed, norbornene-mediated ortho-amination/N-tosylhydrazone insertion reaction. In this transformation, one C-N bond and one C-C bond are formed and an amine group is introduced at the ortho position successfully.

Copper-catalyzed three-component cyanotrifluoromethylation/azidotrifluoromethylation and carbocyclization of 1,6-enynes.

A novel three-component strategy for the cyanotrifluoromethylation/azidotrifluoromethylation and carbocyclization of 1,6-enynes is developed. The reaction proceeds smoothly under a moderate temperature by using a copper catalyst, which provides a rapid and concise access to addition-carbocyclization products. Furthermore, the products obtained can be useful building blocks in discoveries of lead compounds and other biologically active CF3-containing heterocycles.

AgSCF3-Mediated Trifluoromethylthiolation/Radical Cascade Cyclization of 1,6-Enynes

A AgSCF3-mediated radical cascade cyclization/trifluoromethylthiolation of 1,6-enynes triggered by a C-C triple bond is developed. This protocol also provides another opportunity to construct a valuable trifluoromethylthio-substituted polycyclic fluorene system through the formations of one C-SCF3 bond and two C-C bonds in a single step.

Brønsted Acid Catalyzed and NIS-Promoted Cyclization of Diynones: Selective Synthesis of 4-Pyrone, 4-Pyridone, and 3-Pyrrolone Derivatives

Brønsted acid catalyzed tandem cyclization was found to be highly effective for the preparation of a series of polysubstituted 4-pyrones from diynones (yield up to 99%). 4-Pyridone and 3-pyrrolone derivatives were also selectively synthesized by employing NIS and/or Brønsted acid. NIS as an electrophilic reagent could promote these reactions efficiently and rapidly under very mild reaction conditions.

Merging photoredox with copper catalysis: decarboxylative difluoroacetylation of α,β-unsaturated carboxylic acids with ICF2CO2Et

A photoredox-/copper-catalyzed decarboxylative difluoroacetylation reaction of α,β-unsaturated carboxylic acids has been developed. This reaction produces a variety of difluoroalkylated alkenes in moderate to excellent yields and exhibits satisfactory stereoselectivity and a broad substrate scope at ambient temperature. Furthermore, this decarboxylative difluoroacetylation protocol provides efficient and environment friendly access to the difluoroalkylated alkenes.

Gold-Catalyzed Tandem [3,3]-Propargyl Ester Rearrangement Leading to (E)-1H-Inden-1-ones

An efficient method for the synthesis of (E)-1H-inden-1-ones using gold-catalyzed tandem [3,3]-propargyl ester rearrangement followed by Michael addition under mild reaction conditions has been developed. The resulting products are important frameworks found in numerous natural products and pharmaceutically active compounds, as well as being valuable intermediates in organic synthesis.

Iodine-Promoted Radical Cyclization in Water: A Selective Reaction of 1,6-Enynes with Sulfonyl Hydrazides.

An iodine-promoted one-pot radical cyclization reaction of 1,6-enynes with sulfonyl hydrazides to provide five-membered and hexatomic ring sulfonylated products under the same conditions is established. This reaction proceeded smoothly in water and gave the corresponding products by using I2/TBHP instead of expensive and toxic catalysts with C-S and C-I bond formed in one step. This method also allowed easy access to significant functional sulfones for potential applications in medicinal and organic chemistry.

TMSCl-Mediated Synthesis of α,β-Unsaturated Amides via C–C Bond Cleavage and C–N Bond Formation of Propargyl Alcohols with Trimethylsilyl Azide

A new method with high efficiency for the synthesis of α,β-unsaturated amides from the easily prepared propargyl alcohols and TMSN3 using TMSCl as an acid promoter is developed. A wide variety of α,β-unsaturated amides were produced in moderate to excellent yields. Mechanistic studies indicate that this transformation involves TMSCl-mediated allenylazide intermediate formation, C-C bond cleavage, and C-N bond formation. Significantly, this reaction shows good functional group compatibility and high regioselectivity, with a relatively short reaction time and inexpensive reagents.

Regioselective access to CF3S-substituted dihydrofurans from homopropargylic alcohols with trifluoromethanesulfenamide

A facile access to 4-((trifluoromethyl)thio)-2,3-dihydrofurans from unprotected homopropargylic alcohols in high regioselectivity is reported. This method is the first example of using a free hydroxy group as a nucleophile to complete a trifluoromethylthiolation/cyclization protocol with an alkyne in moderate to excellent yields.

Palladium-Catalyzed Regioselective Difluoroalkylation and Carbonylation of Alkynes

A novel, four-component synthetic strategy to synthesize a series of β-difluoroalkyl unsaturated esters/amides with high regioslectivity is described. This Pd-catalyzed difluoroalkylation and carbonylation reaction can be carried out with simple starting materials. Through this protocol, two new C-C bonds (including one C-CF2 bond) and one C-O(N) bond are constructed simultaneously in a single step. The synthetic utility of this reaction system has been certified by the applicability to a wide scope of alkynes and nucleophiles. Preliminary mechanistic studies suggest that the difluoroalkyl radical pathway is involved in this reaction.