20549-37-5Relevant academic research and scientific papers
Temperature-dependent immobilization of a tungsten peroxo complex that catalyzes the hydroxymethoxylation of olefins
Chen, Jizhong,Hua, Li,Chen, Chen,Guo, Li,Zhang, Ran,Chen, Angjun,Xiu, Yuhe,Liu, Xuerui,Hou, Zhenshan
, p. 1029 - 1037 (2015/06/08)
Abstract A tungsten peroxo complex stabilized by the bidentate picolinato ligand has been synthesized and then immobilized successfully on imidazole-functionalized silica. The immobilized tungsten-based catalyst was employed as an efficient catalyst for the one-pot synthesis of β-alkoxy alcohols from olefins and methanol with H2O2. Regarding the catalyst evaluation and the results of characterization by the various methods, it was demonstrated that the immobilization of tungsten peroxo complex was highly temperature-dependent. The tungsten peroxo complex can dissociate and diffuse into the liquid phase at reaction temperature, resulting in a homogeneous reaction. Nevertheless, the catalytically active species was anchored on the imidazole-functionalized silica by hydrogen bonding as the temperature was lowered to 0°C after the reaction, which thus offered a highly effective approach for recycling the catalyst for consecutive cycles. In addition, various olefins can be converted to the corresponding β-alkoxy alcohols with good conversion and selectivity under relative mild conditions by H2O2. Running hot and cold: A tungsten peroxo complex (see picture) can dissociate and diffuse into the liquid phase at the reaction temperature, resulting in a homogeneous reaction. After reaction, the catalytically active species was anchored on the functionalized silica by hydrogen-bonding as the temperature was lowered to 0°C. This offers an effective approach for catalyst recovery and recycling.
Selective Asymmetric Dihyroxylation of Polyenes
Becker, Heinrich,Soler, Marcos A.,Sharpless, K. Barry
, p. 1345 - 1376 (2007/10/02)
The asymmetric dihydroxylation procedure (AD) is applied to a variety of polyenes.In many cases excellent regioselectivities are obtained.The observed selectivities are rationalized in terms of electronic and/or steric inherent to the substrate, superimposed on the substrate's favorable or unfavorable interactions with the binding pocket of the AD ligand.Surprisingly, for medium and large ring olefins with trans-double bonds outstanding enantioselectivities are realized using the pyrimidine ligands.A hexaol of D3 symmetry is prepared from all trans cyclodecatriene.
The Regio- and Stereo-controlled Synthesis of cis-p-Menth-3-ene-1,2-diol by means of a 1,2,4-Trioxane Intermediate
Jefford, Charles W.,Jaber, Amer,Boukouvalas, John
, p. 1916 - 1917 (2007/10/02)
A concise synthesis of (+/-)-cis-p-menth-3-ene-1,2-diol from α-terpinene is described which relies on the regio- and stereo-controlled construction of a 1,2,4-trioxane intermediate; structures proposed for two aroma constituents of Ferula jaeschkeana oil are revised.
