Synthesis of ethers by GaBr3 -catalyzed reduction of carboxylic acid esters and lactones by siloxanes.
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.
Institut für Chemie, Carl-von-Ossietzky-Universität Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26111 Oldenburg (Germany). ursula.biermann@uni-oldenburg.de.
Ursula
U
Biermann
Jürgen O
JO
Metzger
D001965:Bromides / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D060326:Chemistry Techniques, Synthetic; D004952:Esters; D004987:Ethers / Q000138:chemical synthesis*; D005708:Gallium / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D010084:Oxidation-Reduction; D012833:Siloxanes / Q000737:chemistry*
D001965:Bromides; D002264:Carboxylic Acids; D004952:Esters; D004987:Ethers; D007783:Lactones; D012833:Siloxanes; D005708:Gallium
ethers; gallium; lactones; reduction; renewable resources