Recyclable organotungsten Lewis acid and microwave assisted Diels–Alder reactions in water and in ionic liquids
作者:I-Hon Chen、Jun-Nan Young、Shuchun Joyce Yu
DOI:10.1016/j.tet.2004.09.078
日期:2004.12
water-soluble, organotungsten Lewisacid, [OP(2-py)3W(CO)(NO)2](BF4)2 (1), was synthesized and characterized. A series of 1-catalyzed Diels–Alderreactions were investigated under conventional heating or microwave heating conditions. The cycloaddition reactions were efficiently conducted in either water or in an ionicliquid, 1-butyl-3-methylimidazolium hexafluorophosphate. The ionicliquid acts as a powerful
A Diels–Alderreaction in a fluorousbiphasicsystem was accelerated by a hexamericcapsule of resorcinarenebearingfluorousfeet. The reaction takes place predominantly within the capsule, which can be recovered as a fluorous solution and recycled after simple decantation.
In the presence of a Ni–Mg–Al layered triple hydroxide-supported Pd catalyst, the acceptorless dehydrogenative aromatization of a wide range of substrates efficiently proceeded with the liberation of molecular hydrogen.
calcination of the Sn–W hydroxide at 800 °C acts as an effective and reusable solid catalyst for CCbond‐formingreactions, such as the cyclization of citronellal, the Diels–Alder reaction, and the cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (see scheme). The observed catalysis was truly heterogeneous, and the recovered catalyst could be reused without loss of its high catalytic performance
Silver nanoparticles (AgNPs) stabilized by aggregates of derivative 4 have been used as catalyst for the construction of synthetically and biologically important [4 + 2] cycloadducts at room temperature.