Synthesis of 4-Aryl-Substituted Butenolides and Pentenolides by Copper-Catalyzed Hydroarylation
摘要:
We have investigated the effect of the type of protecting group used and the tether length of 4- and 5-hydroxy-substituted 2-alkynoates on the yields and selectivity of the product of hydroarylation. The use of methyl, methoxymethyl, and tert-butyldimethylsilyl (TBS) as protecting groups increased the total yield of the products. While the protected 4-hydroxy-2-butynoates afforded products formed from two or more alkyne substrates, 5-hydroxy-2-pentynoate derivatives exclusively yielded 1:1 adducts. These facts suggest that the product selectivity depends on the distance of the alkoxy group from the alkyne moiety rather than the type of the protecting group. Among the protecting groups used in this study, the TBS group was found to produce butenolides and pentenolides in good total yields via the one-pot hydroarylation/lactonization.
Ligand- and Base-Free Pd(II)-Catalyzed Controlled Switching between Oxidative Heck and Conjugate Addition Reactions
作者:Sarah E. Walker、Julian Boehnke、Pauline E. Glen、Steven Levey、Lisa Patrick、James A. Jordan-Hore、Ai-Lan Lee
DOI:10.1021/ol400539h
日期:2013.4.19
solvent allows controlled and efficient switching between oxidative Heck and conjugateadditionreactions on cyclic Michael acceptor substrates, catalyzed by a cationic Pd(II) catalyst system. Both reactions are ligand- and base-free and tolerant of air and moisture, and the controlled switching sheds light on some of the factors which favor one reaction over the other.
Selective arylation at the vinylic site of cyclic olefins
作者:Xiaojin Wu、Jianrong (Steve) Zhou
DOI:10.1039/c3cc41722k
日期:——
Cyclicolefins usually give Heck products having an aryl ring residing at the allylic or homoallylic position. We describe herein a new method that allows arylation at the vinylic position of various cyclicolefins.
Palladium-Catalyzed Regioselective [5 + 1] Annulation of Vinyl Aziridines/Epoxides with ClCF<sub>2</sub>COONa
作者:Dandan Zuo、Tao Zhang、Jingjing Zhao、Wen Luo、Chaojie Wang、Pan Li
DOI:10.1021/acs.orglett.2c01739
日期:2022.7.1
regioselective [5 + 1] annulation reactions of vinyl aziridines/epoxides with ClCF2COONa have been developed. Significantly, vinyl aziridines/epoxides act as heteroatom-containing five-atom synthons, and commercially available and cheap ClCF2COONa acts as the source of carbonyl serving as a difluorocarbene precursor. This protocol provides an efficient and practical method for the synthesis of δ-lactams and
Rh–IndOlefOx catalyzed conjugate addition/Heck-type coupling of organoboronics to a lactam or a lactone
作者:Noora Kuuloja、Matti Vaismaa、Robert Franzén
DOI:10.1016/j.tet.2012.01.040
日期:2012.3
Four indole-olefin-oxazoline (IndOlefOx) ligands were synthesized and evaluated in Rh-catalyzed reactions between organoboronics and a lactam or a lactone. In addition to the expected conjugate addition products, the formation of significant amounts of Heck-type products was observed. The scope and limitations of these reactions were investigated. (C) 2012 Elsevier Ltd. All rights reserved.