Although a variety of chromium(VI) compounds have been used for oxidation of allylic or benzylic groups, complications in applying these methods remain because of the harsh reaction conditions required and difficult work-up and/or purification procedures. In addition, chromic acid waste products are increasinglyof concern as environmental hazarda.  We have reported using a 2-quinoxalinol salen ligand system - a Schiff-base type ligand with a quinoxaline incorporated into a salen backbone �  as a catalyst support for Cu(II). The 2-quinoxolinol salen (abbreviated salqu) copper complexes have been shown to have an increased catalytic efficacy as compared to a copper salophen complexes in the oxidation of aryl methylenes.  Simple olefin substrates can also be oxidized using the salqu catalyst with TBHP  (up to 99% yield) within a very short reaction time and with great tolerance for additional functional groups. The mechanism has been characterized and compared with theoretical calculations.

2-Quinoxalinol salen copper complexes in C-H activation and oxidation: Mechanism and application

244th National Meeting (2012)

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