Regio- and enantioselectivity in the alkylation and etherification reactions of cinnamyl allylic derivatives catalyzed by [(η5-C5R5)Ru(N–N*)(NCCH3)]PF6 (R = H, Me) complexes containing N–N* bulky chiral ligands of different rigidity and flexibility

[(η5-C5R5)Ru(N–N*)(NCMe)]PF6 (R = H, N–N* = (Sa)-1, 5; (Sa)-2, 6; (R,R)-3, 7; (R,R)-4; 8; R = Me, N–N* = (Sa)-1, 9) complexes containing N–N* bulky chiral ligands of different rigidity and flexibility were synthesized by reacting the precursor [(η5-C5R5)Ru(NCMe)3]PF6 (R = H, Me) with the N–N* ligand in a 1:1 molar ratio. The more bulky (η5-C5Me5) ligand gave low stability to the complexes [(η5-C5Me5)Ru(N–N*)(NCMe)]PF6, when N–N* = (Sa)-2, (R,R)-3, (R,R)-4, in comparison to (η5-C5H5) ligand and prevented their characterization. The catalytic activity of complexes 5–9 in allylic alkylation and etherifications reactions, using malonate and phenoxide anions as nucleophiles respectively, were investigated and compared to the results obtained with corresponding precursors [(η5-C5H5)Ru(NCMe)3]PF6 and [(η5-C5Me5)Ru(NCMe)3]PF6. The effect of bulkiness and of rigidity and flexibility ligand features is discussed.

N–N* chiral ligands with different bulkiness and flexibility features were used in allylic substitution reactions, in which [(η5-C5R5)Ru(N–N*)(NCMe)]PF6 complexes act as precatalysts.Figure optionsDownload as PowerPoint slide