title: Unusually accelerated silylmethyl transfer from tin in stille coupling: implication of coordination-driven transmetalation.
abstract: The palladium-catalyzed cross-coupling reaction of 2-PyMe2SiCH2SnBu3 with aryl iodide (Ar-I) exclusively produced the 2-PyMe2SiCH2 transferred product 2-PyMe2SiCH2Ar. The relative transfer ability of organic group from tin was found to be 2-PyMe2SiCH2 >> Ph > Me > Bu >> PhMe2SiCH2, which implies the beneficial pyridyl-to-palladium coordination effect. Thus, the transfer of the silylmethyl group from tin to palladium was remarkably accelerated by simply appending the 2-pyridyl group on silicon. The pyridyl-to-palladium coordination was validated in the palladium(II) complex 2-PyMe2SiCH2PdClPPh3 by 1H NMR and X-ray crystal structure analysis. The cross-coupling product was used for further transformations. The C-Si oxidation of the cross-coupling product 2-PyMe2SiCH2Ar afforded ArCH2OH in high yield. The fluoride ion-catalyzed 1,2-addition of 2-PyMe2SiCH2Ar to carbonyl compound (RR'C=O) gave ArCH2C(OH)RR' in high yield.
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: J
authors.initials: J
authors.lastname: Yoshida