Facile palladium catalyzed Suzuki–Miyaura coupling in air and water at ambient temperature
作者:Alexander N. Marziale、Stefan H. Faul、Thomas Reiner、Sven Schneider、Jörg Eppinger
DOI:10.1039/b915436a
日期:——
A new palladacyclic catalyst yields high activities in aqueous Suzuki–Miyauracoupling at room temperature. Using an optimized protocol, a broad range of products can be isolated in good to excellent yields and high purity by simple filtration.
An efficient protocol for the palladium-catalysed Suzuki–Miyaura cross-coupling
作者:Alexander N. Marziale、Dominik Jantke、Stefan H. Faul、Thomas Reiner、Eberhardt Herdtweck、Jörg Eppinger
DOI:10.1039/c0gc00522c
日期:——
The palladacyclic catalyst precursor received by ortho-palladation of ([1,1â²-biphenyl]-2-yloxy)diisopropyl-phosphine represents a highly active system for SuzukiâMiyaura cross-coupling reactions when used in neat water. An efficient, broadly applicable and sustainable aqueous protocol was developed using 2.5 eq. of Na2CO3 as base, allowing the reaction to be performed under air and at ambient temperature with Pd loadings of 0.04 mol%. Coupling products are obtained in high yields and excellent purity by simple filtration with no organic solvents needed throughout the whole reaction. A broad variety of functional groups are tolerated and a large number of substrates can be applied with this protocol. The crystal structure of the palladacyclic catalyst precursor is presented as well as investigations targeting the nature of catalyst activation and the active catalytic species.
α-Glucosidase inhibitory antihyperglycemic activity of substituted chromenone derivatives
作者:B. China Raju、Ashok K. Tiwari、J. Ashok Kumar、A. Zehra Ali、Sachin B. Agawane、G. Saidachary、K. Madhusudana
DOI:10.1016/j.bmc.2009.10.047
日期:2010.1
varying degrees of α-glucosidaseinhibitory and DPPHscavengingactivity. Compound 4x emerged as the most potent α-glucosidase inhibitor in present series of compounds owing to the presence of 3-acetyl-6-(6-methoxy-3-pyridyl) group on chromenone; however, it could not display DPPHscavengingactivity and was found to be mixed non-competitive type inhibitor of rat intestinal α-glucosidase. When tested in
Improvements and Applications of the Transition Metal-Free Asymmetric Allylic Alkylation using Grignard Reagents and Magnesium Alanates
作者:David Grassi、Alexandre Alexakis
DOI:10.1002/adsc.201500495
日期:2015.10.12
Two new N-heterocyclic carbene (NHC) ligands have been synthesized and employed in the transition metal-free asymmetric allylic alkylation (AAA) mediated by Grignardreagents and magnesium alanates. The employment of these ligands showed high yields and improved regio- and enantioselectivity in the formation of tertiary and quaternary stereocenters. Moreover, the low catalyst loading (up to 0.3 mol%)
Condensation of salicylaldehydes with ethyl 4,4,4-trichloro-3-oxobutanoate: a facile approach for the synthesis of substituted 2H-chromene-3-carboxylates
作者:Mudulkar Sairam、Gannerla Saidachary、Bhimapaka China Raju
DOI:10.1016/j.tetlet.2015.01.114
日期:2015.3
A highly efficient and simple protocol has been developed for the preparation of ethyl 2-oxo-2H-chromene-3-carboxylates 3a–v by the condensation of salicylaldehydes 1a–v with ethyl 4,4,4-trichloro-3-oxobutanoate 2 for the first time. The reaction is proceeding via Knoevenagel pathway followed by a selective addition of the phenolic hydroxyl group to the carbonyl group adjacent to the CCl3 group rather