Metal-free allylic oxidation with molecular oxygen catalyzed by g-[C.sub.3][N.sub.4] and N-hydroxyphthalimide

• Published in: Catalysis letters Vol. 144; no. 4; pp. 717 - 722
• Main Authors: Liu, Guiyin, Tang, Ruiren, Wang, Zhen
• Format: Journal Article
• Language: English
• Published: Springer 01.04.2014
• Subjects: Boron nitride; Oxidation-reduction reaction
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-014-1200-1

Polymeric graphitic carbon nitride (g-[C.sub.3][N.sub.4]) is a layered graphite-like nitrogen-rich material, bearing the potential ability to reductively adsorb molecular oxygen for catalytic allylic oxidation. Furthermore, N-hydroxyphthalimide (NHPI) has been recognized as an efficient catalyst for aerobic oxidation of various organic compounds under mild conditions in the presence of various co-catalysts. We present here a promising strategy for employing such nitride-rich g-[C.sub.3][N.sub.4] combined with NHPI to form an allorganic metal-free composite and have examined its activity for allylic oxidation with molecular oxygen as the primary terminal oxidant. In the case of allylic oxidation α-isophorone catalyzed by g-[C.sub.3][N.sub.4]/NHPI gave priority to its corresponding carbonyl compound and epoxide. The effects of various reaction conditions on the catalytic reaction were optimized, affording 74.8% conversion with 44.4% selectivity of ketoisophorone at 130°Cin5 h. Repeated runs demonstrated that the catalyst was stable for at least three cycles without noticeable loss of its catalytic activity.