Reversing the Regiochemical Course of 1,3-Dipolar Cycloaddition of Nitrile oxides by Modification of Dipolarophiles
作者:Akio Kamimura、Kenzi Hori
DOI:10.1016/s0040-4020(01)85282-0
日期:1994.1
Cycloaddition to the acetal derivatives preferentially gave the regioisomer bearing acetal group on C(4) position. While the opposite regioselectivity was observed for the cycloaddition to dithioacetal derivatives, where the sulfur functional group was mainly located at C(5) position. Theoretical studies on these regiochemical courses showed the C(5) orientation of dithioacetal groups to be directed
Acetals and ethers-xiii Reaction products of 2-butenal with ethylene glycol
作者:Andrzej Piasecki
DOI:10.1016/s0040-4020(01)91323-7
日期:1984.1
The unsaturated cyclic acetal, 2-(1-propenyl)-1,3-dioxolane (2), has been found as an intermediate product in the p-toluenesulfonic acid catalysed reaction of 2-butenal with an excess of ethyleneglycol. The final product consisted of 2-[2-(2-hydroxyethoxy)-propyl]-1,3-dioxolane (3), and a small amount of geometric isomers of cis- and trans-5-(2-hydroxyethoxy)-7-methyl-1,4-dioxepane (4a and 4b, respectively)
Reactivity of α,β-unsaturated acetals with electrophiles in the presence of organolithium–potassium reagents
作者:Paolo Venturello
DOI:10.1039/c39920001032
日期:——
2-Propenyl- and 2-(2-methylpropenyl)-1,3-dioxane react with 2 equiv. of sec-butyllithium complexed with potassium tert-butoxide in tetrahydrofuran (THF) at â95 °C undergoing a 1,4 eliminative ring fission with subsequent proton abstraction at the α vinyl site of the enol ethers produced; carbanions obtained undergo substitution and addition reactions with electrophiles.