Synthesis of ethers by GaBr3 -catalyzed reduction of carboxylic acid esters and lactones by siloxanes.
Synthesis of ethers by GaBr3 -catalyzed reduction of carboxylic acid esters and lactones by siloxanes.
复制标题
GaBr3 催化硅氧烷还原羧酸酯和内酯合成醚。
作者：
U. Biermann;J. Metzger
以1，1，3，3-四甲基二硅氧烷为还原剂，在溴化镓(GaBr3)催化下，通过对不同酯类的还原反应，合成了相应的醚类化合物。油酸甲酯、甘油三酯，即三丁三胺和甘油三酯-10-烯酸甘油酯以及γ-和δ-内酯以高到中等的产率转化为相应的醚。在存在甲酯官能团的情况下，γ-内酯被高选择性地还原。还原是在室温或中等高温下进行的，最高可达60°C，使用化学计量的还原剂和0.005-0.01当量的溴化镓作为催化剂，每种酯的官能度都是如此，不添加任何溶剂。反应时间1~4h，底物转化率为100%。通过简单蒸馏，将产物与偶联产物聚硅氧烷分离。
Ethers were synthesized by reduction of the respective esters catalyzed by gallium bromide (GaBr3 ) and using siloxanes, preferentially 1,1,3,3-tetramethyldisiloxane, as reductant. Methyl oleate, triglycerides, that is, tributyrine and glyceryl triundec-10-enoate as well as γ- and δ-lactones were converted into the respective ethers in high to moderate yields. γ-Lactones were reduced with high selectivity in the presence of a methyl ester functionality. The reduction has been carried out at room temperature or moderately elevated temperature of up to 60 °C using stoichiometric amounts of the reductant and 0.005-0.01 equiv of GaBr3 as catalyst per ester functionality without any solvent added. After a reaction time of 1-4 h the conversion of the substrate was 100 %. The product was separated from polymeric siloxanes formed as coupled product by simple distillation.