FeCl3-Catalyzed Nucleophilic Substitution of Propargylic Acetates with Enoxysilanes
摘要:
[Graphics]An efficient FeCl3-catalyzed substitution reaction of propargylic acetates with enoxysilanes under mild conditions to afford corresponding gamma-alkynyl ketones has been developed. The substitution reaction is followed by a TsOH-catalyzed cyclization without purification of the gamma-alkynyl ketone intermediates, offering a straightforward synthetic route to tri- or tetrasubstituted furans.
trityl perchlorate, ethynyl vinylketone derivatives regioselectively react with silyl enol ethers to afford the corresponding Michael adducts in high yields. 2-Propynyl ether derivatives also react with silyl enol ethers in the presence of a catalytic amount of trityl perchlorate, to give the corresponding adducts in high yields. In the case of the reaction with 2-propynyl ether derivatives, regioselectivities
Gold-catalyzed cycloisomerization of alk-4-yn-1-ones
作者:Volker Belting、Norbert Krause
DOI:10.1039/b819704k
日期:——
Depending on the substitution pattern and the solvent, the gold-catalyzed cyclization of alk-4-yn-1-ones 1 affords different oxygen heterocycles under mild reaction conditions. Alkynones with one substituent at C-3 undergo a 5-exo-dig cycloisomerization to substituted furans 2, whereas a 6-endo-digcyclization to 4H-pyrans 3 is observed with substrates bearing two substituents at C-3. In alcoholic solvents