Hai-Wei Xu

Highly selective domino multicyclizations for forming polycyclic fused acridines and azaheterocyclic skeletons.

Highly selective four-component domino multicyclizations for the synthesis of new fused acridines and azaheterocyclic skeletons have been established by mixing common reactants in isobutyric acid under microwave irradiation. The reactions proceeded at fast rates and were conducted to completion within 20-30 min. Up to seven new chemical bonds, four rings, and four stereocenters were assembled in a convenient one-pot operation. The resulting hexacyclic and pentacyclic fused acridines and their stereochemistry have been fully characterized and determined by X-ray structural analysis.

Novel Double [3 + 2 + 1] Heteroannulation for Forming Unprecedented Dipyrazolo-Fused 2,6-Naphthyridines

A novel four-component strategy for the efficient synthesis of unprecedented dipyrazolo-fused 2,6-naphthyridines through a double [3 + 2+1] heteroannulation has been described. The bond-forming efficiency, accessibility, and generality of this synthesis make it highly valuable to assemble tetra-heterocyclic scaffolds.

A novel three-component [5 + 1] heterocyclization leading to 2-azafluorenone synthesis and its polyfunctionalizations

An efficient methodology for the synthesis of new and highly functionalized 2-azafluorenones via a three-component domino reaction involving C1-aryl acylation, C3-thiolation, and C4-cyanation has been developed. This domino reaction enables successful assembly of three new sigma bonds including a C-S bond and a C-N bond in a one-pot operation. Features of this strategy include the mild condition, convenient one-pot operation, and short reaction periods (15-30 min).

Base-Promoted Transannulation of Heterocyclic Enamines and 2,3-Epoxypropan-1-ones: Regio- and Stereoselective Synthesis of Fused Pyridines and Pyrroles

Base-promoted transannulation of heterocyclic enamines and 2,3-epoxypropan-1-ones has been successfully achieved, providing a new access to structurally diverse fused pyridines and pyrroles with excellent regio- and stereoselectivity. Treatment with N-aryl 4-aminofuran-2(5H)-ones and 2,3-epoxypropan-1-ones under microwave heating resulted in functional furo[3,2-b]pyridines in good yields. The N-aryl 4-aminopyrrol-2(5H)-ones bearing an electron-withdrawing group engaged in the reaction afforded pyrrolo[3,2-b]pyridines, whereas their counterparts with an electron-neutral or an electron-donating group underwent a different reaction pathway to form pyrrolo[3,2-b]pyrroles through C-C bond cleavage.

A novel domino strategy for forming poly-substituted quaternary imidazoles through a Cs2CO3-promoted aryl migration process

A new domino strategy for the synthesis of highly functionalized quaternary imidazole derivatives via [3 + 2] heterocyclization, involving aryl migration and ring-opening of oxirane, has been developed. This domino reaction enables the successful assembly of three new sigma bonds including two C-N bonds in a simple operation. Features of this strategy include the mild conditions, convenient operation, and short reaction periods (15-20 min).