Aldehydes and ketones, when treated with titanium tetraalkoxides in a hydrocarbon solvent at 20-140°C, undergo aldol condensation to give a, α,β-unsaturated carbonyl compounds. To avoid Meerwein-Ponndorf-Verley type reduction of the carbonyl compounds, titantium tetra-tert-butoxide is used, if the reaction is carried out at higher temperatures. In all other cases titanium tetraisopropoxide can be successfully employed. The outlined procedure offers the possibility of performing aldol condensations under neutral conditions.
醛和酮在20-140°C的烃溶剂中与四烷氧基
钛处理时,会发生醇缩反应,生成α,β-不饱和羰基化合物。为了避免羰基化合物的Meerwein-Ponndorf-Verley型还原,如果反应在较高温度下进行,则使用四-tert-丁氧
钛。在所有其他情况下,四异丙氧
钛可以成功使用。该方法提供了在中性条件下进行醇缩反应的可能性。