Thermal Rearrangements of α-(Acyloxy)silanes. 2. Formation of Chiral Precursors and Migratory Preference of Silicon-Based Groups
The asymmetric reduction of acylsilanes to chiral α-hydroxysilanes and the thermal rearrangement of the corresponding chiral α-acetoxysilanes was employed.Ipc2BCl reduces many acylsilanes in > 95percent ee.The rate of the thermal rearrangement of the α-acetoxysilanes was dependent upon the substituents at both silicon and carbon.Evidence is presented to indicate there is electron deficiency at the α-carbon in the transition state.Migratory aptitudes follow those expected on the basis of the migrating group assuming an apical migratory group at a pentacoordinate silicon.A previously unreported hydrolytic transformation of a proposed acylsilyl hydride to a stable 1-sila-1,2-diol was observed.
Buynak, John D.,Strickland, J. Byron,Lamb, Grady W.,Khasnis, Dipti,Modi, Seema,et al.
p. 7076 - 7083
(2007/10/02)
ALPHA CARBOCATION STABILIZATION BY SILICON, GERMANIUM AND TIN
The hydrolyses of a number of α-metalloidal vinyl ethers were found to undergo a ratel-imiting protonation to produce α- silil, germyl or stannyl carbocations.Comparative rate data leads to the ordering: C>Sn>Ge>Si>H, for the stabilization of such intermediates.
Soderquist, John A.,Hassner, Alfred
p. 1899 - 1902
(2007/10/02)
Alkylation and acylation of some activated aromatic substrates by organosilicon compounds
A method of alkylation and acylation of trinitrobenzene employing the oxidation of anionic ?-complexes generated from organosilicon reagents in the presence of KF/18-crown-6 ether is described.The method enables the introduction of alkyl and acyl substitu
Artamkina, G. A.,Kovalenko, S. V.,Beletskaya, I. P.,Reutov, O. A.
p. 139 - 150
(2007/10/02)
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