Modulation of Borylnitrene Reactivity in CH insertion and CC cycloaddition reactions by intramolecular dative Interactions

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Nitrenes are reactive intermediates in organic synthesis. Borylnitrenes are boron derivatives that are particularly strong electrophilic species in their electronic singlet state. They react unselectively with CH bonds and can even activate the quite inert methane molecule. In this research project heterocyclic borylnitrenes of variable ring size (five to eight membered rings) and with variable hetero element (E = NR, O, S) are to be investigated. The variation of the conformational flexibility with ring size and the donor strength of E modulates the electronic structure and the reactivity of the borylnitrenes through the extend of the strength of the intramolecular E -> N dative interaction. The analysis of the structure – reactivity relationship of the borylnitrenes depending on ring size and donor element in CH insertions and [2+1] cycloadditions as typical representative nitrene reactions is the focus of this research project. Using the method of matrix isolation and classical solution phase product analyses the chemo-, regio-, diastereo- and enantioselectivity of borylnitrene chemistry are to be determined. It is expected that the research project provides fundamental insight into the reactivity of borylnitrenes and that it will be ultimately possible to tune reactivity employing intramolecular dative interactions.