Peiqiu Liao

Cu2O acting as a robust catalyst in CuAAC reactions: water is the required medium

Cu2O as the catalyst in water was found to be quite robust for the azide-alkyne cycloaddition (AAC) reaction, which was verified by a wide variety of applicable azides and alkynes. Water was proved to play an essential role because of a significant rate acceleration compared with reactions using organic solvents and conducted under neat conditions. The high catalytic performance of Cu2O/H2O system was further argued by decreasing the catalyst loading to ppm levels.

Silver-Catalyzed Cross-Coupling of Propargylic Alcohols with Isocyanides: An Atom-Economical Synthesis of 2,3-Allenamides

Cross-coupling reactions between propargylic alcohols and isocyanides, by means of silver catalysis, have been described. This new reaction is both atom and step efficient and is applicable to a broad scope of substrates, allowing the synthesis of a range of synthetically valuable 2,3-allenamides in moderate to excellent yields.

Intramolecular hydrogen bonding-assisted cyclocondensation of α-diazoketones with various amines: a strategy for highly efficient Wolff 1,2,3-triazole synthesis

A catalytic and highly efficient Wolffs cyclocondensation of α-diazoketones with aromatic and aliphatic amines has been realized for the first time by utilizing the strategy of an intramolecular hydrogen bonding-activating carbonyl group. This approach successfully solved the challenging problem of poor condensation efficiency in Wolff 1,2,3-triazole synthesis, and constitutes a powerful method for the synthesis of highly functionalized 1,2,3-triazoles.

Cu(II)-catalyzed cyclization of α-diazo-β-oxoamides with amines leading to pyrrol-3(2H)-ones

A novel Cu(II)-catalyzed cyclization of α-diazo-β-oxoamides with amines has been developed, constituting a straightforward method to construct pyrrol-3(2H)-one rings. The intramolecular hydrogen bonding effect in α-diazo-β-oxoamides plays an essential role in this reaction. A plausible reaction mechanism involving divergent generation and subsequent [2 + 3] cyclization of ketene and α-diazoimine intermediates was proposed.

Lewis and Brønsted Acid Cocatalyzed Reductive Deoxyallenylation of Propargylic Alcohols with 2‐Nitrobenzenesulfonylhydrazide

Reductive deoxyallenylation of sterically hindered tertiary propargylic alcohols was realized on reaction with 2-nitrobenzenesulfonylhydrazide (NBSH) by the combined use of Lewis and Brønsted acid catalysts. This method features a broad substrate scope, mild reaction conditions, and good functional-group tolerance, and affords various mono-, di-, and trisubstituted allenes in good-to-excellent yields. The synthetic utility of this method was demonstrated by the synthesis of 2H-chromenes and 1,2-dihydroquinolines.

Catalytic intramolecular aromatic C–H alkenylation of arenes with non-activated ketones: synthesis of 4-alkylene quinolin-2-ones

The catalytic intramolecular aromatic C-H alkenylation of arenes with non-activated ketone carbonyls has been realized for the first time, leading to the synthesis of antiviral 4-alkylene quinolin-2-ones, where the quaternary carbon adjacent to the ketone carbonyl plays an essential role in this catalytic reaction.

Solvent-controlled, regio-switchable formation of 3-/5-arylaminopyrazole isomer in cyclocondensation of β-aminoenones with hydrazides: intermolecular hydrogen bonding plays a role

An unprecedented solvent-controlled, regio-switchable Knorr-type reaction for the synthesis of pyrazoles has been realized in the cyclocondensation of β-aminoenones with hydrazides. Single regioisomer of 3- or 5-arylaminopyrazole can be obtained simply by changing the reaction solvent. Using hydrazine hydrate, only 3-arylaminopyrazoles were produced.

Vilsmeier cyclization of α-acetyl-α-aroyl ketene-N,S-acetals: direct and efficient synthesis of halogenated pyridin-2(1H)-ones

An efficient synthetic route to 3-aroyl-5-formyl-4-halo pyridin-2(1H)-ones has been developed via Vilsmeier cyclization of 2-(ethylthio(arylamino)methylene)-1-alkylbutane-1,3-dione. The synthetic protocol has demonstrated the first example of Vilsmeier cyclization of α-acetyl-α-aroylketene-N,S-acetals, providing a novel route to 4-bromo/chloro pyridin-2(1H)-ones.