High pressure-promoted cycloadditions of ketene acetals and α,β-unsaturated aldehydes and ketones
作者:René W.M. Aben、Hans W. Scheeren
DOI:10.1016/s0040-4039(00)94766-x
日期:1985.1
Cycloadditions of keteneacetals with α,β-unsaturated carbonyl compounds are strongly promoted by high pressure. The influence of the solvent and the substitution pattern on the product distribution at 12 kBar has been investigated. In the polar solvent, acetonitrile, α,β-unsaturated aldehydes not having large β-substituents, yield mainly cyclobutane aldehydes, which are minor products at normal pressure
Acid-catalysedhydrolysis of 2,2-dimethoxy-3,4-dihydropyrans () yields mixtures of δ-keto esters () and 3,4-dihydro-α-pyrones (). The amount of increases with increasing alkyl substitution in the 3-, 5- and 6-position of and when the hydrolysis is carried out in a two-phases system of water/dichloromethane. It is shown that is formed directly from whereas is formed directly from and by methanolysis