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.

A novel and efficient procedure for the synthesis of g-alkynyl ketones by the nucleophilic substitution of propargylic acetates with enoxysilanes in the presence of a catalytic amount of Copper(II) triflate, has been developed. The substitution reaction can be followed by a 4-toluenesulfonic acid-catalyzed cyclization without purification of the g-alkynyl ketone intermediates, offering a straightforward synthetic route to polysubstituted furans.

2008 C-C bond formation O 0282FeCl3-Catalyzed Nucleophilic Substitution of Propargylic Acetates with Enoxysilanes. -The reaction offers a new, mild, and efficient approach to γ-alkynyl ketones, which are also available from propargylic phosphates and the keto ester (VI). In some cases formation of allenyl isomers is also observed. Subsequent treatment with TosOH provides a straightforward route to highly substituted furans. -(ZHAN*, Z.-P.; CAI, X.-B.; WANG, S.-P.; YU, J.-L.; LIU, H.-J.; CUI, Y.-Y.; J. Org. Chem. 72 (2007) 25, 9838-9841; Dep. Chem., Xiamen Univ., Xiamen 361005, Fujian, Peop. Rep. China; Eng.) -Jannicke 17-042

2008 Furan derivatives R 0060Copper(II) Triflate-Catalyzed Nucleophilic Substitution of Propargylic Acetates with Enoxysilanes. A Straightforward Synthetic Route to Polysubstituted Furans.-An appealing alternative to currently available methods to γ-alkynyl ketones and trior tetra-substituted furans is described. The reactions are completed rapidly within a short time under mild conditions. Air or moisture are tolerated. -(ZHAN*, Z.-P.; WANG, S.-P.; CAI, X.-B.; LIU, H.-J.; YU, J.-L.; CUI, Y.-Y.; Adv. Synth. Catal. 349 (2007) 13, 2097-2102; Dep. Chem., Xiamen Univ., Xiamen 361005, Fujian, Peop. Rep. China; Eng.) -Bartels 04-103