Phenylpyridine derivatives

More recently, the Shi group reported an ort/to-halogenation of acetylanilide with copper(ll) as oxidant (Scheme 15) [43]. Cu(II) salt was also found to be crucial to the formation of chloroarenes in the Pd(II)-catalyzed reaction of 2-phenylpyridine derivatives with arylsulfonyl chlorides. Only sulfonylation was observed when no copper was present in the system (Scheme 16) [44]. 

Considering that organofluorine compotmds feature prominently in the pharmaceutical and agrochemical industries due to their important biological activities [2, 48], there were significant efforts to extend the above methods to making fluoroaromatic compormds. Sanford et al. reported a Pd-catalyzed C-H activa-tion/ort/ro-fluorination of several 2-phenylpyridine derivatives with various N-F donors of an electrophilic fluorine (Scheme 18) [49]. Under the same conditions. 

Recently, Esmaeilbeig et al. [72] reported on an antitumor activity study of cycloplatinum compounds containing 2-phenylpyridine derivatives, as shown in Eq. (9.1). Antitumor effects of 2-phenylpyridine platinum 1-inidazole, 4-methylpyridine, pyridine, and 4,4 -bipyridine derivatives were determined for Jukat, K562, and Raji cell lines, and the results showed reasonable cytotoxicities. 

These cyclometalation compounds are van Koten s carbosilane pincer nickel dendrimer 9.54 [109, 111], pincer SCS palladium dendrimer 9.55 [110, 112], azobenzene platinum chloro-bridged liquid crytal 9.56 [113, 114], and N,N-dimethylnaphthylene palladium resolving agent 9.57 [117-119] as shown in Fig. 9.10, and photosensitizers for hydrogen production, bis(2-phenylpyridine-4-methyl,4 -fluoride) 9.59 and other photosensitizers with bis(2-phenylpyridine) derivatives 9.60 as shown in Fig. 9.11 [120,121]. 

Fig. 9.11 Two examples of 2-phenylpyridine derivatives as photosensitizers 9.58, and 9.59 for hydrogen production [120,121]...

A comprehensive review of the chemistry of these compounds was compiled several years ago by Henderson, thus filling in, at that time, a gap in the vast and rich field of organogold chemistry [48]. First examples are the 2-(phenylazo)phe-nyl and 2-[(dimethylamino)methyl] phenyl complexes 1 [49] and 2 [50] reported by the group of Vicente and the 2-phenylpyridine derivative 3 [51] reported by Constable and coworkers (Figure 4.4). 

Scheme 17.4 C-H/C-X coupling of 2-phenylpyridine derivatives with aryl halides under ruthenium catalysis.

Phenylpyridine derivatives with substituent on the 4-position of the phenyl ring react to give the corresponding phenylated products in excellent yields. The reaction is relatively fast when the phenyl group is equipped with an electron-donating group. 

Example 7.25 Cobalt-Catalyzed Monobromination of a Phenylpyridine Derivative [ 144]. 

The reaction conditions proved to be remarkably mild and even highly sensitive substrates such as ( )-croton aldehyde could be converted into the corresponding aryl ketone. The procedure is also applicable for the aiylation of naturally occurring aldehydes, and this has been demonstrated by the coupling of enantiomerically pure (S)-citronellal. The group of Cheng developed a complementary Pd(OAc)2-catalyzed aerobic protocol that is highly efficient for the acylation of 2-phenylpyridine derivatives with electron-rich, electron-deficient and heterocyclic aromatic aldehydes (Scheme 1.39). ... 

Kametani, T., K. Ogasawara, and M. Shio Streptonigrin and Related Compounds. III. Syntheses of 4-Phenylpyridine Derivatives. Yakugaku Zasshi 86, 809 (1966). 

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