Gold-Catalyzed Hydrosilyloxylation Driving Tandem Aldol and Mannich Reactions

The chemoselective formation of an enolate from alkyne in the presence of a carbonyl and imine group was realized, which constructed a variety of structural motifs under exceedingly mild reaction conditions in a tandem process. Reaction driving tandem hydrosilyloxylation/aldol reactions was achieved through the formation of enol silyl ethers catalytically generated in situ from readily available alkynes. These reactions were expanded to obtain β-amino enol silyl ethers in good yields <i>via</i> the tandem hydrosilyloxylation/isomerization/Mannich reaction

Indium Tri(isopropoxide)-Catalyzed Selective Meerwein–Ponndorf–Verley Reduction of Aliphatic and Aromatic Aldehydes

Indium tri­(isopropoxide)-catalyzed Meerwein–Ponndorf–Verley reduction of aliphatic and aromatic aldehydes in 2-propanol gave selectively the corresponding primary alcohols in good to excellent yields at room temperature. A wide range of functional groups including alkene, ether, ketone, ester, nitrile, and nitro were tolerated under the optimum reaction conditions. Chemoselective reductions were also achieved not only between aromatic aldehyde, aromatic ketone, and epoxide but also between aliphatic aldehyde and alkene

Synthesis of Indenes via Brønsted Acid Catalyzed Cyclization of Diaryl- and Alkyl Aryl-1,3-dienes

Substituted indenes can be synthesized via the Brønsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes. In this approach, treatment of symmetric or unsymmetric diaryl- and alkyl aryl-1,3-dienes with a catalytic amount of trifluoromethanesulfonic acid gives a variety of indene derivatives in good to excellent yields under mild conditions

Diastereoselective <i>N</i>‑Sulfonylaminoalkenylation of Azulenes from Terminal Alkynes and Azides via<i> N</i>-Sulfonyl-1,2,3-triazoles

The development of rhodium-catalyzed diastereoselective <i>N</i>-sulfonylaminoalkenylation of azulenes using <i>N</i>-sulfonyltriazoles is described. This procedure can be successfully applied to rhodium-catalyzed diastereoselective <i>N</i>-sulfonylaminoalkenylation of azulenes starting from terminal alkynes and <i>N</i>-sulfonylazides via a three-component semi-one-pot process

Synthesis of Phosphaisocoumarins through Rhodium-Catalyzed Cyclization Using Alkynes and Arylphosphonic Acid Monoesters

A rhodium-catalyzed cyclization using alkynes and arylphosphonic acid monoesters for the synthesis of phosphaisocoumarins is reported. A number of arylphosphonic acid monoesters were selectively cyclized in high yields with functional group tolerance. In addition, unsymmetrical alkynes are applied in high regioselectivity

Synthesis of Azulen-1-yl Ketones via Oxidative Cleavage of C–C Multiple Bonds in <i>N</i>‑Sulfonyl Enamides and 1‑Alkynes under Air and Natural Sunlight

A synthetic method to prepare azulen-1-yl ketones was developed via oxidative cleavage of the C–C double bond in the reaction of easily obtainable <i>N</i>-sulfonyl enamides with Cs₂CO₃ under air and natural sunlight and in the absence of a photosensitizer. Oxidative cleavage of C–C triple bonds was also demonstrated for the synthesis of azulen-1-yl ketones via a tandem Cu-catalyzed [3 + 2] cycloaddition, Rh-catalyzed arylation, photooxygenation, and ring-opening reaction in one pot under air and natural sunlight

Synthesis of Imidazopyridines via Copper-Catalyzed, Formal Aza-[3 + 2] Cycloaddition Reaction of Pyridine Derivatives with α‑Diazo Oxime Ethers

The Cu-catalyzed, formal aza-[3 + 2] cycloaddition reaction of pyridine derivatives with α-diazo oxime ethers in trifluoroethanol was used to synthesize imidazopyridines via the release of molecular nitrogen and elimination of alcohol. These methods enabled modular synthesis of a wide range of <i>N</i>-heterobicyclic compounds such as imidazo­pyridazines, imidazo­pyrimidines, and imidazo­pyrazines with an α-imino Cu-carbenoid generated from the α-diazo oxime ethers and copper

Synthesis of Imidazopyridines via Copper-Catalyzed, Formal Aza-[3 + 2] Cycloaddition Reaction of Pyridine Derivatives with α‑Diazo Oxime Ethers

The Cu-catalyzed, formal aza-[3 + 2] cycloaddition reaction of pyridine derivatives with α-diazo oxime ethers in trifluoroethanol was used to synthesize imidazopyridines via the release of molecular nitrogen and elimination of alcohol. These methods enabled modular synthesis of a wide range of <i>N</i>-heterobicyclic compounds such as imidazo­pyridazines, imidazo­pyrimidines, and imidazo­pyrazines with an α-imino Cu-carbenoid generated from the α-diazo oxime ethers and copper

Synthesis of Diaryl Ketones through Oxidative Cleavage of the C–C Double Bonds in <i>N</i>‑Sulfonyl Enamides

An oxidative cleavage of a C–C double bond is developed from the photochemical [2+2]-cycloaddition of diaryl <i>N</i>-tosyl enamides, aryl heteroaryl <i>N</i>-tosyl enamides, and <i>N</i>-tosyl cyclic enamides with singlet molecular oxygen, followed by a ring-opening reaction mediated by Cs₂CO₃ under air and sunlight without the use of photosesitizer, producing symmetrical and unsymmetrical diaryl, heterodiaryl, and cyclic ketones in good to excellent yields. Moreover, the oxidative cleavage of C–C triple bonds from 1-alkynes is demonstrated for the synthesis of symmetrical and unsymmetrical ketones from the Cu-catalyzed [3+2]-cycloaddition, Rh-catalyzed alkoxyarylation, photooxygenation, and ring-opening reaction in one-pot. Because the synthesis of the symmetrical and unsymmetrical diaryl and/or heterodiaryl ketones bearing an electron-donating group is not easy, the present method is notable