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
Synthesis of Novel Dendritic 2,2‘-Bipyridine Ligands and Their Application to Lewis Acid-Catalyzed Diels−Alder and Three-Component Condensation Reactions
作者:Takahito Muraki、Ken-ichi Fujita、Masato Kujime
DOI:10.1021/jo070767a
日期:2007.10.1
dendritic Cu(OTf)2 catalysts were used for Diels−Alder and three-component condensationreactions. The dendritic Cu(OTf)2-catalyzed Diels−Alder reaction proceeded smoothly, and these dendritic catalysts could be recycled without deactivation by reprecipitation. Three-component condensationreactions such as Mannich-type reactions also proceeded not only in dichloromethane but also in water. Furthermore
Scandiumtrifluoromethanesulfonate (Sc(OTf)3) is found to be quite effective as a Lewis acid catalyst in the Diels-Alder reaction. The novel catalyst is available in both aqueous and organic media, is easily recovered from aqueous layer after the reaction is completed, and can be reused.
Studies on quinones. Part 40: Synthesis and cytotoxicity evaluation of anthraquinone epoxides and isomerization products
作者:Jaime A. Valderrama、Omar Espinoza、M. Florencia González、Ricardo A. Tapia、Jaime A. Rodríguez、Cristina Theoduloz、Guillermo Schmeda-Hirschmann
DOI:10.1016/j.tet.2005.12.038
日期:2006.3
dihydroalkanoquinones which, depending on their structures, react with in situ generated hydroperoxide anion to give quinoneepoxides and/or hydroperoxides. The calcium hydroxide-induced rearrangement of quinoneepoxides yielded furan-containing angular quinones. The cytotoxic activities of quinoneepoxides and their isomerization products were evaluated in vitro against normal human lung fibroblasts (MRC-5) and