FLP behaviour of cationic titanium complexes with tridentate Cp, O, N -ligands: Highly efficient syntheses and activation reactions of C-X bonds (X = Cl, F)
Fischer M., Schwitalla K., Baues S., Schmidtmann M., Beckhaus R.
The synthesis of cationic titanium complexes 4a,b with tridentate Cp,O,N-ligand frameworks, starting from the monopentafulvene complex Cp∗Ti(Cl)(π-η 5 :σ-η 1 -C 5 H 4 CR 2 (CR 2 = adamantylidene) (1) and bidentate O,N-ligand precursors CH 3 C(O)CH 2 CH 2 NR 2 (R = Et, CH 2 Ph) (L1a,b), in a high-yielding and efficient two-step synthetic pathway is described. The β-aminoketones L1a,b were synthesized by a herein reported solvent- and catalyst-free reaction. The reaction pathway involves insertion reactions, subsequent methylations and final activations with B(C 6 F 5 ) 3 . NMR investigations of the cationic titanium complex 4a in deuterated dichloromethane revealed an ongoing selective reaction under formation of the cationic complex 5a-d 2 , which is the result of C-Cl bond cleavage. In addition to selective C-Cl bond activation reactions, C(sp 3 )-F bonds were activated by 4a,b, pointing out the special tm-FLP nature of 4a,b.