3-bromo-5-phenylpyridine

Ciamician reported the formation of 3-halogenopyridines in low yield from the reaction of pyrryl potassium with chloroform, or bromo-form, in ether. Similar reactions of pyrrole with benzal chloride and methylene iodide gave 3-phenylpyridine and traces of pyridine, respectively. These reactions were later reinvestigated by Alexander... 

The Hiyama cross-coupling of organosilanes is attractive as the intermediates are often easy to prepare and the silicon by-products are environmentally benign. A one-pot synthesis of 2-aryl-3-methylpyridines from 2-bromo-3-methylpyridine was developed (Scheme 25) <2003JOM58>. Both 2- and 3-bromopyridine cross-couple with phenyltrimethoxysilane to afford the corresponding phenylpyridines in good yield <19990L2137>. 

Larock found that the reaetion of 2-iodo -methylbiphenyl (34) with acrylate provided two products 35 and 36 in equal amounts using cesium pivalate as a base. Of course, 35 is an expected produet [27]. Also the reaction of 37 afforded the mixture of 35 and 36. Gallagher also diseovered a similar migration using 3-bromo-4-phenylpyridine (38) and acrylate to afford 39 and 40 [28]. Although the mechanism of the migration process to form the crossover produets is not clear, certainly a reversible 1,4-Pd shift of arylpalladium intermediates 41 and 43 via the palladacycle 42 is occurring. 

The scope of various pyridine derivatives with 1-hexene was examined with L45c-Sc/[Ph3C][B(C6F5)4] as the catalyst (Table 5.8). The asymmetric alkylation of 2-Me, 2-Et, 2- Pr, 2- Bu, and 2-phenyl-substituted pyridines 188 could also be achieved similarly in high yields (83-94%) and enantioselectivity (up to 94 6 er) (entries 1-5). Notably, the C—H bond activation reaction occurred selectively at the pyridine unit rather than at the phenyl group in the case of 2-phenylpyridine, which is in contrast with the reactions catalyzed by late transition metal complexes. The iodo, bromo, and chloro substituents in the picoline substrates are well compatible (entries 6-8). No alkylation reaction was observed with unsubstituted pyridine or quinoline, probably due to the poisoning effect of the N atom of pyridine to the metal center. 

Bromo-2-phenylpyridine, 9CI, 8CI CijHgBrN M 234.095 Pale yellow liq. BP720 305-307°. 

Bromo-4-phenylpyridine, B-80245 2-Bromo-5-phenylpyridine, B-80246 2-Bromo-6-phenylpyridine, B-80247... 

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