Xiaoqing Xin

Regioselective Synthesis of 3-Arylamino- and 5-Arylaminoisoxazoles from Enaminones

A highly regioselective synthesis of 3-arylamino- and 5-arylaminoisoxazoles from enaminones based on reaction condition selection is reported. 3-Arylaminoisoxazoles were produced by treating enaminones with aqueous hydroxylamine in DMF at 100 °C, whereas 5-arylaminoisoxazoles were synthesized by subjecting enaminones to aqueous hydroxylamine in the presence of KOH and TBAB in water under reflux. A mechanism for the regioselective synthesis of 3-arylamino- and 5-arylaminoisoxazoles is proposed.

Copper-catalyzed three-component reaction: solvent-controlled regioselective synthesis of 4-amino- and 6-amino-2-iminopyridines.

Regioselective synthesis of multisubstituted 4-amino- and 6-amino-2-iminopyridines has been developed via the copper-catalyzed three-component reaction based on the reaction conditions selection. The reaction of sulfonyl azides, alkynes, and 2-[(amino)methylene]malononitriles catalyzed by copper(I) iodide in tetrahydrofuran at room temperature afforded substituted 4-amino-2-iminopyridines, whereas, in N,N-dimethylformamide at 50 °C under N2, it generated substituted 6-amino-2-iminopyridines as predominant products.

PPA-Mediated C–C Bond Formation: A Synthetic Route to Substituted Indeno[2,1-c]quinolin-6(7H)-ones

A facile and efficient synthesis of substituted indeno[2,1-c]quinolin-6(7H)-ones from a variety of α-acyl N-arylcinnamamides mediated by polyphosphoric acid (PPA) is described, and a mechanism involving the formation of a dicationic superelectrophile and subsequent double intramolecular nucleophilic cyclization reactions is proposed.

Homogeneous and Stereoselective Copper(II)-Catalyzed Monohydration of Methylenemalononitriles to 2-Cyanoacrylamides

A facile and efficient route for the homogeneous and highly stereoselective monohydration of substituted methylenemalononitriles to (E)-2-cyanoacrylamides catalyzed by copper(II) acetate monohydrate in acetic acid containing 2% water is described, and a mechanism is proposed. The protocol has proved to be suitable for the monohydration of dicyanobenzenes and 2-substituted malononitriles.

One-pot synthesis of substituted 2,5-dihydrofurans from β-oxo amides and cinnamaldehydes

A facile and efficient one-pot synthesis of substituted 2,5-dihydrofurans from cinnamaldehydes and β-oxo amides is described, and a mechanism involving the intramolecular oxidative cyclization of penta-2,4- dienamides, i.e. Knoevenagel condensation products, forming a new C–O bond in the presence of phenyliodine diacetate (PIDA) is proposed.

BF3·Et2O-mediated intramolecular cyclization of unsaturated amides: convenient synthesis of dihydroquinolin-2-one-BF2 complexes

A facile and efficient synthesis of substituted dihydropyridone–BF2 complexes is developed via intramolecular cyclization of α-acyl acrylamides and α-acyl cinnamamides mediated by BF3·Et2O.

Synthesis of multi-substituted 4-aminopyridines via ring-opening and recyclization reactions of 2-iminopyridines

A novel synthesis of multi-substituted 4-aminopyridines from 2-iminopyridines by a two-step procedure is described. During this transformation, 4-amino-2-iminopyridines undergo a regioselective ring-opening reaction in the presence of KOH in t-butanol to afford 5-oxo-pent-3-enimidamides, which are then converted into 4-aminopyridines in toluene under reflux following a 6π-azaelectrocyclization and N-to-N 1,3-sulfonyl group migration mechanism.