Application of silacyclic allylsilanes to the synthesis of β-hydroxy-δ-lactones: synthesis of Prelactone B
Silacyclic allylsilanes generated through a silene-diene Diels-Alder cycloaddition represent versatile bifunctional reagents for organic synthesis. This is demonstrated in a short stereocontrolled synthesis of (±)-Prelactone B.
Evidence for silicon-directed acid-catalysed ring opening of a β,γ-epoxy silane: Reaction of 1,1-dimethyl-1-silacyclohex-3-ene oxide with p-nitrobenzoic acid
The ring-opening reaction of the β,γ-epoxy silane (4) with p-nitrobenzoic acid in chloroform occurs regiospecifically to give the two hydroxy esters (14) and (15). The mechanism involves regiospecific ring opening giving the β-silicon-stabilized carbenium ion (18) which is captured by the p-nitrobenzoate counter ion. The solution conformation of (14) provides evidence for the presence of σC-Si-σ*C-O interactions between the ring C-Si bonding orbital and the C-OCOC6H4NO2 antibonding orbital. In acetone, reaction of (4) with p-nitrobenzoic acid takes a different pathway and results in acyclic products from solvent attack at the silicon.
Badali, Fatmir,Karalis, Andrew,Tham, Wai Ying,White, Jonathan M.
p. 1293 - 1299
(2007/10/03)
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