A general preparation for aromatic and aliphatic, cyclic as well as linear, symmetric and asymmetric difluoromethylenedioxy derivatives is described. The alcohols were reacted with thiophosgene to give thiocarbonates, which in turn were reacted with BrF(3). The fluorination step is complete in seconds with moderate to high yields under mild conditions.
Hydrogenation of CO<sub>2</sub>
-Derived Carbonates and Polycarbonates to Methanol and Diols by Metal-Ligand Cooperative Manganese Catalysis
作者:Viktoriia Zubar、Yury Lebedev、Luis Miguel Azofra、Luigi Cavallo、Osama El-Sepelgy、Magnus Rueping
DOI:10.1002/anie.201805630
日期:2018.10.8
The first base‐metal‐catalysed hydrogenation of CO2‐derived carbonates to alcohols is presented. The reaction proceeds under mild conditions in the presence of a well‐defined manganese complex with a loading as low as 0.25 mol %. The non‐precious‐metal homogenous catalytic system provides an indirect route for the conversion of CO2 into methanol with the co‐production of value‐added (vicinal) diols
Bifunctionalorganocatalysts bearing an ammonium betaine framework have been developed as a new catalytic motif for the activation of carbondioxide and epoxides to produce cyclic carbonates.
catalysts of N‐iodopyridinium halide featured with N−I bond were synthesized and evaluated in CCE reactions. The optimal XBD catalyst, 4‐(dimethylamino)‐N‐iodopyridinium bromide ([DMAPI]Br), under screened conditions at 100 °C, ambient pressure, and 1 mol % catalyst loading, realized 93 % conversion of styrene oxide into cyclic carbonate in 6 h. The substratescope was successfully extended with excellent
与氢键平行的卤素键被引入到二氧化碳到环氧化物(CCE)反应的催化环加成中。合成了一系列具有N-1键的N-碘吡啶鎓卤化物的卤素键供体(XBD)催化剂,并在CCE反应中进行了评估。最佳XBD催化剂,4-(二甲氨基)-N-溴化碘吡啶鎓([DMAPI] Br),在100°C,环境压力和1 mol%催化剂负载的筛选条件下,实现了93%的氧化苯乙烯转化为环状碳酸酯在6小时内 底物范围成功扩大,并具有优异的收率(大多数≥93%)和定量选择性(超过99%)。1个底物环氧化物上的催化剂[DMAPI] Br的1 H NMR光谱证明,N-1键与环氧基直接配位。提出了一种可能的卤素键催化机理,其中DMAPI阳离子起卤素键供体的作用来激活环氧化物,而抗衡阴离子溴化物攻击亚甲基碳以引发环氧化物的开环。N-碘吡啶鎓卤化物促进的CCE反应是环氧活化和CO 2转化中卤素键催化的第一种情况。
Versatile and scalable synthesis of cyclic organic carbonates under organocatalytic continuous flow conditions
作者:Romaric Gérardy、Julien Estager、Patricia Luis、Damien P. Debecker、Jean-Christophe M. Monbaliu
DOI:10.1039/c9cy01659g
日期:——
epoxides. In this work, cyclic organic carbonates are prepared according to alternative sustainable and intensified continuousflow conditions from the corresponding 1,2-diols. The process utilizes dimethyl carbonate (DMC) as a low toxicity carbonation reagent and relies on the organocatalytic activity of widely available and cheap organic ammonium and phosphonium salts. Glycerol is selected as a model
We first achieved direct synthesis of propylene carbonate from CO2 and 1,2-propanediol in excellent yield (>99%) using a carboxylation/hydration cascade catalyst of CeO2 with 2-cyanopyridine. The catalyst system can be applied to syntheses of various cyclic carbonates, including 6-membered ring carbonates that are difficult to synthesize in high yields (62−>99%).