Cu(I) β-diketiminates for alkene aziridination:: Reversible Cu-arene binding and catalytic nitrene transfer from Phl=NTs

beta-Diketiminato Cu(I)-lutidine complexes [RMeNN]Cu(2,4-lutidine) (R = Me (4a), Pr-i (4b)) were prepared in high yield from TI[RMeNN] and [CuBr(2,4-lutidine)(2)](2). Both 4a and 4b reversibly dissociate lutidine base in toluene to give [RMeNN]Cu(toluene) solvento complexes. A related base-free dicopper species {[Me2NN]Cu}(2) (6) bridged via eta(2)-binding of opposing N-aryl rings could be isolated by the addition of TI[Me2NN] to CuBr. The lutidine precursors serve as precatalysts for the aziridination of alkenes with PhI=NTs. Styrene, beta-methylstyrene, and cyclooctene gave the highest yields (59-96%) with a low olefin to Phl=NTs ratio (3:1) and 5 mol % catalyst loading.