Boron Trifluoride Mediated Ring-Opening Reactions of trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates. Synthesis of Aroylmethylidene Malonates as Potential Building Blocks for Heterocycles
摘要:
trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates, upon treatment with BF3 center dot OEt2, undergo ring-opening rearrangement and the Nef reaction to give aroylmethylidene malonates. The products are found to be potential precursors for heterocycles, such as imidazoles, quinoxalines, and benzo[1,4]thiazines.
thiourea moiety and an amino group on a chiral scaffold. Among them, thiourea 1e bearing 3,5-bis(trifluoromethyl)benzene and dimethylamino groups was revealed to be highly efficient for the asymmetric Michael reaction of 1,3-dicarbonyl compounds to nitroolefins. Furthermore, we have developed a new syntheticroute for (R)-(-)-baclofen and a chiralquaternarycarboncenter with high enantioselectivity by Michael
我们在手性支架上合成了一类带有硫脲部分和氨基的新型双功能催化剂。其中,带有 3,5-双(三氟甲基)苯和二甲氨基的硫脲 1e 被证明对于 1,3-二羰基化合物到硝基烯烃的不对称迈克尔反应非常有效。此外,我们通过迈克尔反应开发了 (R)-(-)-巴氯芬和具有高对映选择性的手性季碳中心的新合成路线。在这些反应中,我们假设催化剂的硫脲部分和氨基分别活化硝基烯烃和 1,3-二羰基化合物,以提供具有高对映选择性和非对映选择性的迈克尔加合物。
Immobilization of 1,5,7-triazabicyclo [4.4.0] dec-5-ene over mesoporous materials: An efficient catalyst for Michael-addition reactions under solvent-free condition
作者:Pranjal Kalita、Rajiv Kumar
DOI:10.1016/j.apcata.2011.03.010
日期:2011.4
Immobilization of 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD, a bicylic guanidine base) over mesoporous material like SBA-15 has been found to be an excellent catalyst for Michael-addition of β-nitro styrene with malonate. The reactions were performed under solvent-free condition at 373 K for 9 h. A wide variety of Michael donors and acceptors were investigated. Among them, high yield of Michael product
Efficient Stereoselective Synthesis of Nitrocyclopropanes by the Oxidative Cyclization of Michael Adducts of Nitroolefins with Activated Methylene Compounds
作者:Renhua Fan、Yang Ye、Weixun Li、Lingfei Wang
DOI:10.1002/adsc.200800452
日期:2008.11.3
An efficientoxidative cyclopropanation of the Michaeladducts of nitroolefins with activatedmethylenecompounds by the combination of iodobenzene diacetate and tetrabutylammonium iodide is reported. Highly functionalized nitrocyclopropanes are synthesized in moderate to good yields via the Michael addition and cyclopropanation with high diastereoselectivity and enantioselectivity under mild conditions
Iodobenzene-Catalyzed Oxidative Cyclization for the Synthesis of Highly Functionalized Cyclopropanes
作者:Yang Li、Hao Guo、Renhua Fan
DOI:10.1055/s-0039-1690809
日期:2020.3
iodobenzene-catalyzed oxidative cyclization of Michael adducts of activated methylene compounds with nitroolefins or chalcones is developed. mCPBA is used as oxidant together with Bu4NI for the generation of a highly reactive iodine(III) species to mediate the cyclopropanation via a ligand exchange and reductive elimination process. A range of highly functionalized cyclopropanes are synthesized with
An efficient strategy for the mechanosynthesis of gamma-nitro dicarbonyl esters has been developed. A CaCl2-catalyzed Michael reaction, conducted at room temperature, afforded nitroalkenes from malonates in a short reaction time and in high yields. In most cases, polymerized side-reactions are eliminated or minimized. (C) 2013 Elsevier Ltd. All rights reserved.