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Selective Oxidation of an Active Intramolecular Amine/Borane Frustrated Lewis Pair with Dioxygen
Tongdao Wang1, Gerald Kehr1, Lei Liu2
1Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster , Corrensstrasse 40, 48149 Münster, Germany.
Abstract:
Oxidation reactions are rarely encountered in frustrated Lewis pair (FLP) chemistry. We describe the selective reaction of an amine/borane FLP with molecular oxygen. The trimethylene-bridged amine/borane frustrated Lewis pair was prepared by hydroboration of N-allyl-tetramethylpiperidine with Piers' borane [HB(C6F5)2]. The intramolecular N/B system undergoes a variety of typical FLP reactions. It is a very active hydrogen splitting reagent at ambient conditions. Its reaction with dioxygen takes place rapidly at ambient conditions to give a tetrahydroisoxazolium/borate salt. A possible pathway of its formation is proposed and supported by DFT calculations.
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