Waste-Free Catalytic Propargylation/Allenylation of Aryl and Heteroaryl Nucleophiles and Synthesis of Naphthopyrans
作者:J. McCubbin、Costa Nassar、Oleg Krokhin
DOI:10.1055/s-0030-1260146
日期:2011.10
pyrroles, as well as methoxy-substituted benzenes and naphthalenes. Reaction with 2-naphthol affords substituted naphthopyrans as products. Preliminary evidence suggests a Friedel-Crafts-like substitution mechanism, which occurs via an in situ generated carbocation. organocatalysis - boronic acids - propargylic alcohols - Friedel-Craftsreaction
An unexpected thermal-ring-rearrangement of benzochromenes to inden-3-yl-naphthols with <i>p</i>TsOH
作者:Srinivasarao Yaragorla、Tabassum Khan
DOI:10.1039/c8ob02264j
日期:——
Described here is the first report of an unexpected thermal-ring rearrangement (TRR) of benzochromenes to indene derivatives promoted by pTsOH, which proceeds through the protonation of benzochromenes by an acid catalysts followed by ring-opening and ring-closure by an intramolecular Friedel–Crafts cyclization.
这里描述了苯基色酮发生意外的热环重排(TRR)生成茚衍生物的首次报告,此过程由
TsOH
促进,通过酸催化剂对苯基色酮的质子化,随后通过分子内弗里德尔-克拉夫茨环化反应进行环的开启和闭合。
Regioselective annulation of propargyl alcohols with ambident-enols: A Ca(II)-catalyzed trisubstituted benzochromene synthesis
cyclization between propargyl alcohols and ambident enols such as naphthols, 4-hydroxy coumarin, cyclohexane-1,3-dione, 5,5-dimethylcyclohexane-1,3-dione is described using Ca(OTf)2 under solvent free conditions. The reaction proceeds through a cascade annulation which involves an etherification, Claisen type rearrangement, allene formation and endocyclization. Further, we extended this method to the synthesis
Iron-Catalyzed Direct Synthesis of Densely Substituted Benzofurans and Naphthopyrans from Phenolic Compounds and Propargylic Alcohols
作者:Feng-Quan Yuan、Fu-She Han
DOI:10.1002/adsc.201200804
日期:2013.2.1
propargylic alcohols in the presence of 5 mol% of iron(III) chloride hexahydrate (FeCl3⋅6 H2O) catalyst. On the other hand, pyran derivatives were obtained exclusively when tertiary propargylic alcohols were employed. Mechanistic studies revealed that presumably due to the discriminated steric effect of secondary and tertiary propargylic alcohols, the Fe-catalyzed Friedel–Crafts (F–C) reaction of phenols
1-(1H-inden-3-yl)naphthalen-2-ols. This intramolecular cycloetherification proceeds via C(sp2)–H oxygenation (C–H bond breaking and C–O bond forming), which enables the atom-economical synthesis of poly fused furans in high yields with large substrate diversity in the open air.