Metal-free annulative hydrosulfonation of propiolate esters: synthesis of 4-sulfonates of coumarins and butenolides
作者:Rodney A. Fernandes、Ashvin J. Gangani、Rupesh A. Kunkalkar
DOI:10.1039/c9nj06438a
日期:——
An efficient metal-free and cost-effective method for the synthesis of coumarin and butenolide 4-sulfonates has been developed involving addition of sulfonic acids to ethyl propiolates followed by lactonization.
Gold(I)-Catalyzed Tandem Alkoxylation/Lactonization of γ-Hydroxy-α,β-Acetylenic Esters
作者:Rubén S. Ramón、Christophe Pottier、Adrián Gómez-Suárez、Steven P. Nolan
DOI:10.1002/adsc.201100115
日期:2011.6
The formation of 4‐alkoxy‐2(5H)‐furanones was achieved via tandemalkoxylation/lactonization of γ‐hydroxy‐α,β‐acetylenic esters catalyzed by 2 mol% of [2,6‐bis(diisopropylphenyl)imidazol‐2‐ylidine]gold bis(trifluoromethanesulfonyl)imidate [Au(IPr)(NTf2)]. The economic and simple procedure was applied to a series of various secondary propargylic alcohols allowing for yields of desired product of up
<sup>
n
</sup>Bu<sub>4</sub>NPF<sub>6</sub> promoted regioselective cascade synthesis of functionally embellished naphthofurans under acid, metal & solvent free conditions
作者:Abhishek Pareek、Ravikrishna Dada、Monika Rana、Anuj K. Sharma、Srinivasarao Yaragorla
DOI:10.1039/c6ra17411f
日期:——
n Bu4NPF6 mediated highly regioselective synthesis of functionally embellished naphthofurans has been achieved from easily available naphthols and propargyl alcohols through a cascade benzylation, oxacyclisation (5-exo dig) and isomerization undersolventfreeconditions. The reaction works in a short time through dibenzyl ether formation followed by the decomposition to the carbocation to furnish
An efficient and highly regio-selective synthesis of fused & substituted furans has been described using Ca(OTf)2 as the catalyst. This tandem process involves alkylation, 5-exo dig cyclisation and isomerization to furnish densely substituted furans under solvent free conditions. A case study of regioselectivity has been demonstrated.