Visible-Light-Promoted aza-Henry Reaction Using Mesoporous Cu₂O

Key words

mesoporous copper(I) oxide - photocatalytic aza-Henry reaction - visible light - oxygen

Significance

Mesoporous copper(I) oxide spheres with different pore sizes (5 nm for SP-Cu₂O and 15 nm for LP-Cu₂O) were prepared and applied to the visible-light-promoted aza-Henry reaction. The reaction of N-aryl tetrahydroisoquinolines 1 with nitroalkanes 2 was carried out in the presence of LP-Cu₂O and molecular oxygen under the irradiation of blue LEDs to afford the corresponding coupling products 3 in 83–90% yield. The reaction without catalyst gave 3a in only 5% yield under otherwise similar conditions.

 

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Comment

The catalysts were characterized by SEM, TEM, XRD, and N₂ adsorption–desorption analyses. For the formation of 3a, LP-Cu₂O was recovered by centrifugation and reused four times without significant loss of catalytic activity. SEM observation of LP-Cu₂O after the fifth run showed no change of its morphology. The preparation of mesoporous Cu₂O spheres with small pore size was previously reported by Shang, Zhang and Guo (J. Mater. Chem. 2012, 22, 856).

 

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