A convenient and versatile procedure for the straightforward synthesis of substituted fluorenones as valuable scaffolds is described under rhodium catalysis. The present [2 + 2 + 2] cycloadditionreaction of diynes with 3-acetoxy or-3-alkoxyindenones as surrogates of the highly reactive benzocyclopentynone 2π partner allows the preparation of various fluorenone-type derivatives in good yields and provides
Synthesis of Substituted 2,2′‐Bipyridines and 2,2′:6′,2′′‐Terpyridines by Cobalt‐Catalyzed Cycloaddition Reactions of Nitriles and α,ω‐Diynes with Exclusive Regioselectivity
reactions exhibiting exclusive regioselectivity. Thus, symmetrical and unsymmetrical 1,6-diynes and 2-cyanopyridine reacted in the presence of 5 mol % of dppe, 5 mol % of CoCl2⋅6 H2O and 10 mol % of zinc powder to provide the corresponding 2,2′-bipyridines. Under identical reaction conditions, 1-(2-pyridyl)-1,6-diynes and nitriles reacted smoothly with exclusive regioselectivity to produce 2,2′-bipyridines
Regioselective Syntheses of Substituted Pyridines and 2,2′-Bipyridines by Cobalt-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Nitriles
作者:Sentaro Okamoto、Yu-ki Sugiyama
DOI:10.1055/s-0030-1260068
日期:2011.7
2-bis(diphenylphosphino)ethane-cobalt(II) chloride-zinc catalyst in 1-methylpyrrolidin-2-one at room temperature to 50 ˚C, α,ω-diynes reacted with nitriles by a [2+2+2] cycloaddition pathway to give annulated pyridines or 2,2′-bipyridines. The regioselectivity of the reaction is controlled by a combination of steric and electronic effects. The reaction of diynes with a terminal trimethylsilyl group gave the
Ru<sub>3</sub>(CO)<sub>12</sub>-Catalyzed Reaction of 1,6-Diynes, Carbon Monoxide, and Water via the Reductive Coupling of Carbon Monoxide
作者:Cathleen M. Crudden、Yuuki Maekawa、Joshua J. Clarke、Tomohide Ida、Yoshiya Fukumoto、Naoto Chatani、Shinji Murai
DOI:10.1021/acs.orglett.0c02349
日期:2020.11.20
We report the ruthenium-catalyzed cyclization of 1,6-diynes with two molecules of carbonmonoxide and water to give a variety of catechols. This reaction likely proceeds through the intermediacy of the water–gas shift reaction to generate an yne–diol-type intermediate followed by a [4 + 2] cycloaddition with 1,6-diynes. The reaction requires no external reductants or hydride sources and provides a
Diols, α-Ketols, and Diones as 2<sub>2π</sub> Components in [2+2+2] Cycloadditions of 1,6-Diynes via Ruthenium(0)-Catalyzed Transfer Hydrogenation
作者:Hiroki Sato、Matthias Bender、Weijie Chen、Michael J. Krische
DOI:10.1021/jacs.6b11746
日期:2016.12.21
The first use of vicinal diols, ketols, or diones as 2(2 pi) components in metal-catalyzed [2+2+2] cycloaddition is described. Using ruthenium(0) catalysts, 1,6-diynes form ruthenacyclopentadienes that engage transient diones in successive carbonyl addition. Transfer hydrogenolysis of the resulting ruthenium(II) diolate mediated by the diol or ketol reactant releases the cycloadduct with regeneration of ruthenium(0) and the requisite dione.