Synthesis and Structure of Novel Mn~(III) and Mn~V Complexes: Development of a New, Mild Method for Forming Mn=N Bonds

摘要

The numerous reaction methods for converting alkenes to epoxides or diols are of enormous value and are commonly employed in chemical synthesis. In contrast, far fewer methods are available for the analogous conversion of an alkene to an aziridine oran amine. despite their great potential utility. We are currently exploring the development of nitridomanganese systems that may be activated for N-atom transfer to alkenes. We have reported that silyl enol ethers could be aminated with [(salen)Mn=N] complexes (salen = N,N'-bis(salicylidene)ethylenediamine dianion) in the presence of trifluoroacetic anhydride (TFAA) to give N-trifluoroacetylated alpha-amino ketones. In an effort to expand the scope of this class of reagents, we have focused on the design and synthesis of novel nitridomanganese complexes. Herein we describe the preparation and X-ray crystallographic characterization of Mn~(III) and nitridomanganese(v) complexes containing Schiff bases as ligands. The generation of such Mn~v nitrides (Mn=N) (Scheme 1) has required the development of a mild oxidative protocol. Additionally, we demonstrate the ability of these nitrides to transfer a CF_3CON unit to an unfunctionalized olefin by the successful animation of styrene. a substrate which was unreactive with previously reported Mn = N complexes.