Syntheses and NMR study of [(2-dimethylaminomethyl)phenyl]vinylsilane derivatives and [(2-dimethylaminomethyl)phenyl]ethylsilane derivatives

Various vinylsilanes, SiX(CHCH2)(CH3)[2-(CH3)2NCH2C6H4], and ethylsilanes, SiX(CH2CH3)(CH3)[2-(CH3)2NCH2C6H4] [X=Cl (1); OMe (2); H (3); F (4); OSiMe3 (5); NMe2 (6); Me (7)], were synthesized in order to investigate the electronic effect of vinyl group on silicon atom having an intramolecular coordination arm. The magnitude of Δδ (ethyl→vinyl for 29Si-NMR) of chlorosilane, 1, was the biggest one among 1–7. The differences of 29Si chemical shifts between vinylsilanes and ethylsilanes increased in the following order: X=Me, NMe2