Novel Method for Synthesizing Spiro[4.5]cyclohexadienones through a Pd-Catalyzed Intramolecular <i>ipso</i>-Friedel−Crafts Allylic Alkylation of Phenols
The first successful Pd-catalyzed intramolecular ipso-Friedel−Crafts allylic alkylation of phenols, which provided a new access to spiro[4.5]cyclohexadienones, is described. The present method could be applied to catalytic enantioselective construction of an all-carbon quaternary spirocenter.
Synthesis of spiro[4.5]cyclohexadienones with an allene motif via a base-promoted intramolecular ipso-Friedel–Crafts addition of phenols to propargyl bromides
novel synthetic method for allenyl spiro[4.5]cyclohexadienone derivatives based on a base-promoted intramolecular ipso-Friedel–Crafts addition of phenols to propargyl bromides. The present spirocyclization proceeded in a CH2Cl2–tert-BuOH mixed solvent system using potassium tert-butoxide as the base, and produced the corresponding spiro[4.5]cyclohexadienone derivatives with an allene motif in up to 99%
<b>Electrochemical Dearomatizing Spirocyclization of Alkynes with D</b>imethyl 2-Benzylmalonate<b>s to Spiro[4.5]deca-trienones</b>
作者:Laiqiang Li、Zhong-Wei Hou、Pinhua Li、Lei Wang
DOI:10.1021/acs.joc.2c00939
日期:2022.7.1
dimethyl 2-benzylmalonates for the preparation of spiro[4.5]deca-trienones has been developed. This approach adopts ferrocene (Cp2Fe) as an electrocatalyst to produce carbon-centered radical intermediates from C–H-based malonates, which obviates the forthputting of noble-metal reagents, sacrificial chemical oxidants and 2-bromomalonates. A wide variety of spiro compounds are efficiently prepared with satisfactory
AbstractWe have developed a novel synthetic method to furnish spiro[4.5]cyclohexadienones using an gold‐catalyzed carbocyclization of phenols with a terminal alkyne via an intramolecular ipso‐Friedel–Crafts alkenylation. Using 2–5 mol% of gold catalyst, 1 equiv. of methanesulfonic acid, and 1 equiv. of 2,6‐di‐tert‐butylpyridine, a variety of spiro[4.5]cyclohexadienone derivatives with an exo‐cyclic olefin unit was obtained in good to excellent yields. The divergent synthesis of dihydronaphthalene derivatives was also examined based on the newly developed gold catalysis.magnified image