Preparation of new chiral dioxomolybdenum complexes heterogenised on modified USY-zeolites - Efficient catalysts for selective epoxidation of allylic alcohols
Preparation of new chiral dioxomolybdenum complexes heterogenised on modified USY-zeolites - Efficient catalysts for selective epoxidation of allylic alcohols
复制标题
DOI：
10.1016/1381-1169(95)00224-3
复制
发表时间：
1996-05-06
影响因子：
--
通讯作者：
Sanchez, F
中科院分区：
文献类型：
--
作者：
Corma, A;Fuerte, A;Sanchez, F
以（2S，4 R）-4-羟基脯氨酸为手性配体，通过钼（VI）配合物的合成，合成了一系列钼（VI）配合物。通过共价键将含Si（OEt）（3）基团的配合物异质化到改性USY沸石上。所有的催化剂，均相和多相的，是积极的和区域选择性的烯丙醇在室温下使用叔丁基过氧化氢作为终端氧化剂的环氧化反应。多相配合物的催化活性一般与相应的均相配合物相当，得到环氧醇具有优异的产率和选择性以及中等的对映选择性。多相催化剂的寿命已通过重复使用导致类似的速率和环氧化物的产率的络合物进行了检查，同时在几次运行中没有观察到明显的金属损失。
A series of dioxomolybdenum(VI) complexes were synthesised by reaction of Mo(VI) complexes with new chiral ligands derived from (2S,4R)-4-hydroxyproline. The complexes bearing a Si(OEt)(3) group were heterogenised to a modified USY-zeolite by covalent bonding. All catalysts, homogeneous and heterogenised, are active and regioselective in the epoxidation of allylic alcohols at room temperature using tert-butyl hydroperoxide as terminal oxidant. The catalytic activity of the heterogenised complexes is generally comparable with the corresponding homogeneous ones, yielding epoxyalcohols with excellent yields and selectivity and moderate enantioselectivity. Life time of heterogenised catalysts has been examined by repeated use of the complexes leading similar rates and yields of epoxide, whilst no appreciable loss of metal has been observed over several runs.