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2-Vinylpyridines react with alkenes in the presence of rhodium(r) as catalyst to give alkylated products.The formation of C-C bonds by activation of n-unsaturated C-H bonds is of particular value. Transition metal complexes have been reported to activate the C-H bonds.' Vinylic C-H activation of the olefins has been especially investigated.2 Alkylation at the vinylic position of alkenes via C-H bond activation by RhI has not been reported. Recently, Trost et al.3 and Muria et al.4 independently reported that addition of C-H bonds in trisubstituted a,P-enones to alkenes was successfully achieved by use of (Ph3P)3RuH2(CO) as a catalyst. During the course of our studies of alkylation using rhodium complex catalysts,5 we have found that 2-vinylpyridines reacted with olefins at the @position in the presence of the rhodium(1) complex, (Ph3P)3RhC1, as a catalyst to give the highly chemoselective cross coupled f3-alkylated products.Treatment of 2-isopropenylpyridine l a and 2-a-styrylpyridine l b with 5 equiv. of alkene 2 in toluene with 10% (Ph3P)3RhCl 3 at 100-130 "C gave excellent isolated yields of the linear alkylated products 4, respectively (Scheme 1). Other alkylated and self-dimerized products of 1 could not be detected in the reaction mixture. When an excess amount of 2 was used compared to l a [2 : l a = 5,2; R'=Me(CH&], the reaction time to completion was 19 h (Table 1, run 1). But when the ratio was 10, the reaction took 4 h (run 2). The results of the alkylation are listed in Table 1. The alkylated products of l a were a mixture of trans-and cis-isomers in a 9 : 1 ratio. 2-a-Styrylpyridine l b reacted with hex-1 -ene at low temperature to exclusively give the cis-isomer in an 8% yield (run 8). As the reaction temperature increased, the ratio of trans-isomer increased as shown in run 9. 3,3-Dimethylbut-l-ene also gave the bisalkylated product in a minor amount together with the monoalkylated product (run 12).

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2-Phenylpyridines react with olefins in the presence of rhodium(\) as a catalyst to give 2-(2-alkylphenyl)pyridines by a regioselective alkylation at the ortho position of the phenyl ring.

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