Highly Regioselective Heck Coupling Reactions of Aryl Halides and Dihydropyran in the Presence of an NHC-Pyridine Ligand
作者:Kyung Jung、Jamie Jarusiewicz、Kyung Yoo
DOI:10.1055/s-0028-1087528
日期:2009.2
The Heck coupling reactions of aryl halides and 3,4-dihydro-2H-pyran facilitated the regioselective synthesis of arylated cyclic enol ethers. Good yields were obtained using 5 mol% of an NHC-ligand-Pd-catalyst complex in the presence of K2CO3 in DMF at 100 ËC. The use of this catalytic system broadens the substrate scope and improves the selectivity for this cross-coupling process.
Experimental and Computational Study of an Unexpected Iron-Catalyzed Carboetherification by Cooperative Metal and Ligand Substrate Interaction and Proton Shuttling
作者:Osama El-Sepelgy、Aleksandra Brzozowska、Luis Miguel Azofra、Yoon Kyung Jang、Luigi Cavallo、Magnus Rueping
DOI:10.1002/anie.201708240
日期:2017.11.20
An iron‐catalyzedcycloisomerization of allenols to deoxygenated pyranose glycals has been developed. Combinedexperimental and computationalstudies show that the iron complex exhibits a dual catalytic role in that the non‐innocent cyclopentadienone ligand acts as proton shuttle by initial hydrogen abstraction from the alcohol and by facilitating protonation and deprotonation events in the isomerization
Direct C–H Cyanation by ICN Formed <i>In Situ</i>: Nannozinone B
作者:Paul Wienecke、Hans-Dieter Arndt
DOI:10.1021/acs.orglett.3c00176
日期:2023.2.24
A novel method for C–H cyanation of different pyrans, pyrroles, indoles, and acyclic nucleophilic double bonds using TMSCN, NIS, and Zn(OTf)2 as a catalyst is described. The transformation is conducted under mild conditions tolerating a variety of functional groups. Zn(OTf)2 is likely to serve a dual catalytic role as an activator for TMSCN and for the cyanogen iodide generated in situ. Optimization
The scope of the Heck arylation of enol ethers with arenediazonium salts: a new approach to the synthesis of flavonoids
作者:Angelo H.L. Machado、Marcio A. de Sousa、Daniela C.S. Patto、Luiz F.S. Azevedo、Fernanda I. Bombonato、Carlos Roque D. Correia
DOI:10.1016/j.tetlet.2009.01.017
日期:2009.3
The scope of the Heck arylation of cyclic and acyclic enol ethers with arenediazonium salts was evaluated. Arylation of 2,3-dihydrofuran yielded 2-aryl-2,5-dihydrofurans as the major adducts (>99:1) except when using n-Bu4NHSO4 as additive or 4-NO2PhN2BF4 as arenediazonium salt. 2,3-Dihydropyran provided mixtures of the three possible isomeric Heck adducts. Arylation of n-butylvinylether with arenediazonium bearing electron-donating groups resulted in substituted acetophenones as almost exclusive products in good overall yields, Substituted 4H-chromenes provided 2-aryl-2H-chromenes in moderate yield when applying the Pd(OAc)(2)/2,6-di-t-butyl-4-methylpyridine catalytic system, which were applied in the synthesis of flavonoids. (C) 2009 Elsevier Ltd. All rights reserved.
Straightforward Access to a Structurally Diverse Set of Oxacyclic Scaffolds through a Four-Component Reaction
作者:Oscar Jiménez、Guillermo de la Rosa、Rodolfo Lavilla