About the Stereoelectronics of the Intramolecular Addition of Allylsilanes to Aldehydes
摘要:
(Z)-omega -Trimethylsilyl-(omega -2)-alken-1-ols are readily accessible by consecutive superbase metalation and silylation of (omega -1)-alken-1-ols. These versatile intermediates may be oxidized to give the corresponding (Z)-omega -trimethylsilyl-(omega -2)-alkenals which, in the presence of trifluoroacetic acid, can be converted into 2-vinylcycloalkanols such as 2-vinylcyclohexanol (2), isopulegol (4), and bis(2 vinylcyclobutyl) ether (8). The stereochemical outcome of these cyclization reactions suggests the interference of a novel electrodynamic effect.
Silicon-directed Norrish type I cleavage of β-trimethylsilyl cycloalkanones
作者:Jih Ru Hwu、Bryant A. Gilbert、Lung Ching Lin、Ben Ruey Liaw
DOI:10.1039/c39900000161
日期:——
The Me3Si group in β-trimethylsilylcycloalkanones was able to direct the NorrishtypeIcleavage by providing regioselectivity in the C-1-C-2 bond cleavage and by increasing the quantum yield and the reaction rate.
(Z)-omega -Trimethylsilyl-(omega -2)-alken-1-ols are readily accessible by consecutive superbase metalation and silylation of (omega -1)-alken-1-ols. These versatile intermediates may be oxidized to give the corresponding (Z)-omega -trimethylsilyl-(omega -2)-alkenals which, in the presence of trifluoroacetic acid, can be converted into 2-vinylcycloalkanols such as 2-vinylcyclohexanol (2), isopulegol (4), and bis(2 vinylcyclobutyl) ether (8). The stereochemical outcome of these cyclization reactions suggests the interference of a novel electrodynamic effect.
Intramolecular Ene and Related Reactions, Part 9. Photochemically Induced Synthesis of Allylsilane Carbaldehydes
作者:Lutz F. Tietze、Josef R. Wünsch
DOI:10.1055/s-1990-27070
日期:——
Allylsilane carbaldehydes are valuable substrates for the tandem Knoevenagel allylsilane and iminium cyclization. They can easily be prepared by a photochemical α-cleavage of cyclic ketones bearing a trimethylsilylmethyl group in the α-position (Norrish Type I cleavage). The photolytic process is facilitated by the silicon due to its stabilization of a radical in the β-position. Irradiation of the ketones 15a-d leads mainly to the aldehydes 16a-d. In addition irradiation of 19a gives mostly the aldehyde 20.