Hydrosilylation reaction of various fluoroalkylated alkynes with Et(3)SiH in the presence of a catalytic amount of Co(2)(CO)(8) was investigated. The hydrosilylation of the alkynes having fluoroalkyl and aryl groups took place smoothly with good regioselectivity (ca. 80:20). In sharp contrast, the reaction of the alkynes having a fluoroalkyl group and a benzyl-type substituent, or various propargyl alcohols gave the corresponding vinylsilanes in an excellent regio- and stereoselective manner. Treatment of the vinylsilanes with various aldehydes in the presence of Zn(OTf)(2) and TBAF afforded the coupling products in good yields.

Treatment of various fluorinated internal alkynes with 10 mol% of RhCl(3).H(2)O and 30 mol% of i-Pr(2)NEt in toluene at the reflux temperature for 18 h gave the corresponding trimerization products as an isomeric mixture in high yields. Cycloaddition using 1.0 equiv. of fluorinated alkynes and 2.0 equiv. of non-fluorinated alkynes under the same reaction conditions as in the trimerization led to mono- and bis-fluoroalkylated benzene derivatives in high yields, together with small amounts of trimerization products. The reaction of fluorine-containing bispropargyl ether with non-fluorinated alkynes took place smoothly to afford the corresponding bicyclic molecules in good to high yields.

The reactions of fluoroalkylated acetylides with various nitrones were investigated. When nitrones with an alkyl substituent were employed, hydroxylamines were obtained in high yields, and smooth dehydroxylation followed, to give the corresponding propargylamines. Nitrones with an aryl substituent underwent nucleophilic addition and subsequent intramolecular cyclization, affording the corresponding fluoroalkylated dihydroisoxazoles in moderate yields. These sequences were also extended to chiral versions.

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