title: Pyridyl group assisted deprotonation of a methyl group on silicon: complex induced proximity effect and novel hydroxymethylation.
abstract: A novel methodology for the deprotonation of a methyl group on silicon has been developed. This newly developed alpha-lithiation protocol is based on the intramolecular pyridyl group coordination to stabilize the alpha-silyl carbanion together with the inherent silicon alpha effect. It was found that the deprotonation (t-BuLi/Et(2)O/-78 degrees C) occurs with 2-pyridyltrimethylsilane but not with other related silanes such as phenyltrimethylsilane, 3-pyridyltrimethylsilane, and 4-pyridyltrimethylsilane. It seems that this deprotonation proceeded through the agency of the complex-induced proximity effect (CIPE) of a 2-pyridyl group on silicon. (1)H NMR analysis of (2-pyridyldimethylsilyl)methyllithium revealed the intramolecular coordination of a pyridyl group to lithium. (2-Pyridyldimethylsilyl)methyllithium was found to react with chlorosilanes, hydrosilanes, chlorostannanes, bromine, iodine, organic bromides, aldehydes, and ketones in good to excellent yields. The resultant adducts were further oxidized with H(2)O(2)/KF to give the corresponding alcohols in excellent yields. Thus, this two-step transformation provides an efficient method for the nucleophilic hydroxymethylation.
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Yoshida, Kyoto 606-8501, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Itami
authors.forename: T
authors.initials: T
authors.lastname: Kamei
authors.forename: K
authors.initials: K
authors.lastname: Mitsudo
authors.forename: T
authors.initials: T
authors.lastname: Nokami
authors.forename: J I
authors.initials: JI
authors.lastname: Yoshida