Palladium-catalyzed aryl halide carbonylation–intramolecular O-enolate acylation: efficient isocoumarin synthesis, including the synthesis of thunberginol A
作者:Andrew C. Tadd、Mark R. Fielding、Michael C. Willis
DOI:10.1039/b917839b
日期:——
Exposure of a series of α-(o-haloaryl)-substituted ketones to palladium-catalyzed carbonylation conditions leads to the formation of the corresponding isocoumarins. Balloon pressure of CO is sufficient to achieve high yielding reactions, and both cyclic and acyclic ketones are efficient substrates. The utility of the method is illustrated by a short synthesis of the natural product thunberginol A.
Iron and Copper Salts in the Synthesis of Benzo[b]furans
作者:Julien Bonnamour、María Piedrafita、Carsten Bolm
DOI:10.1002/adsc.201000269
日期:——
Intramolecular CO bond forming reactions of aryl 2‐bromobenzyl ketones lead to benzo[b]furans. The cyclizations can be catalyzed by 10 mol% of iron trichloride (of 98% or of 99.995% purity) or sub‐mol% quantities of copper(II) chloride (of 99.995% purity).
芳基2-溴苄基酮的分子内CO键形成反应导致苯并[ b ]呋喃。10 mol%的三氯化铁(纯度为98%或99.995%)或亚摩尔%的氯化铜(II)(纯度为99.995%)可以催化环化反应。
RuPHOX–Ru catalyzed asymmetric hydrogenation of α-substituted tetralones <i>via</i> a dynamic kinetic resolution
The efficient RuPHOX–Ru catalyzed asymmetric hydrogenation of α-substituted tetralones via a dynamic kineticresolution has been achieved for the synthesis of chiral tetrahydronaphthols. The mechanism study indicated that hydrogenation with H2 gas, rather than transfer hydrogenation with EtOH solvent as the hydrogen source, predominates in the reaction pathway.
Herein, we report that palladium catalyzes the borylative cyclization of α-(2-bromoaryl) ketones to afford 1,2-benzoxaborinines. The developed system is compatible with a variety of functionalities (Me, t-Bu, OMe, NMe2, F, Cl, CN, CF3, CO2Me, and heteroaryl groups) and is applicable to the synthesis of B–O-containing tri- and tetracyclic fused-ring compounds.
Palladium-catalysed intramolecular enolate O-arylation and thio-enolate S-arylation: synthesis of benzo[b]furans and benzo[b]thiophenes
作者:Michael C. Willis、Dawn Taylor、Adam T. Gillmore
DOI:10.1016/j.tet.2006.05.004
日期:2006.12
Enolates derived from alpha-(ortho-haloaryl)-substituted ketones undergo palladium-catalysed C-O bond formation to deliver benzofuran products in good yield. A catalyst generated from Pd-2(dba)(3) and the ligand DPEphos effects the key bond formation to deliver a variety of substituted products from both cyclic and acyclic precursors. The analogous thio-ketones undergo C-S bond formation using identical reaction conditions and are converted to benzothiophene products. A cascade sequence that produces the required a-aryl ketones in situ has also been developed, although the substrate scope is more restricted. (c) 2006 Elsevier Ltd. All rights reserved.