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.

On treatment of various fluorinated internal alkynes with 1.2 equiv of hexabutylditin under the influence of 2.5 mol % of Pd(t-BuNC)(2)Cl(2) in THF at room temperature for 4 h, the bisstannylation proceeded smoothly to afford the corresponding bisstannylated cis-adducts in high yields. Thus obtained adducts were subjected to the Stille cross-coupling reaction to give the corresponding tetrasubstituted fluorine-containing alkenes with defined stereochemistry in good yields.

On treating fluorine-containing internal alkynes with 1.2 equiv. of (trimethylsilyl)tributyltin in the presence of 2.5 mol% of Pd(PPh3)2Cl2 in THF at the reflux temperature for 6 h, the silylstannylation reaction proceeded smoothly to afford the corresponding silylstannylated adducts in high yields in a highly regio- and cis-selective manner. Switching the palladium catalyst from Pd(PPh3)2Cl2 to Pd(t-BuNC)2Cl2 promoted the formation of silylstannylated adducts with opposite regioselectivity. The thus obtained silylstannylated adducts were subjected to Stille cross-coupling reactions to furnish the corresponding fluoroalkylated vinylsilanes whose C-Si bond was converted to a C-C bond by treating with aldehyde in the presence of TBAF and Zn(OTf)2, the corresponding fluoroalkylated tetra-substituted alkenes being afforded in moderate to good yields with a defined stereochemistry.

Alkenes. -The Pd-catalyzed silylstannylation of fluorine containing internal alkynes (I) affords the corresponding adducts (III)/(IV) in a cis-selective manner in good to high yields. Two regioisomers can be prepared selectively by using appropriate Pd-catalysts. -(KONNO*, T.; KINUGAWA, R.; ISHIHARA, T.; YAMADA, S.; Org. Biomol. Chem. 12 (2014) 10, 1611-1617, http://dx.doi.org/10.1039/c3ob41903g ; Dep. Chem. Mater. Technol., Kyoto Inst. Technol., Sakyo, Kyoto 606, Japan; Eng.) -M. Paetzel 28-025

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