2-Iodo-5-alkyl pyridine

Similar examples of regioselective metalation of 3-alkylpyridine-BF3 complexes with the use of TMP-zincate were reported by Michl and co-workers in 2002 [70]. The reaction occurred at the less hindered one of the two reactive positions, as evidenced by trapping of the pyridyl zincates with iodine to afford the 2-iodo-5-alkyl pyridine derivatives in good yields (Eq. 19). 

The intramolecular additions of alkoxyl groups to carbon-carbon double bonds to give P-iodo-alkyl ethers from alkyl hypoiodites under photolytic conditions have been reported. Suginome and collaborators found that the formation of a-iodoepoxides arising from an intramolecular a, P-addition of an allylic alkoxyl radical is a major general process in the photolysis of tertiary and some secondary allylic alcohol hypoiodites in the presence of mercury (11) oxide and iodine in benzene. Thus, 5-hydroxy-SP-cholest-3-ene gave epimeric a-iodoepoxides in a ratio of 10 1 in 86% yield as outlined in Scheme 86. Similar reaction of l-alkylcyclohex-2-en-l-ols gave a mixture of cis- and tr s-a-iodoepoxides (Scheme 87). The addition of pyridine dramatically enhanced the yield of the addition product. The yields of the a-iodoepoxides obtained from the photolysis of l-alkylcyclohex-2-en-l-ols and the ratios of cis- to trans-isomers are summarized in Table 109.1. 

Imidazolium ligands, in Rh complexes, 7, 126 Imidazolium salts iridium binding, 7, 349 in silver(I) carbene synthesis, 2, 206 Imidazol-2-ylidene carbenes, with tungsten carbonyls, 5, 678 (Imidazol-2-ylidene)gold(I) complexes, preparation, 2, 289 Imidazopyridine, in trinuclear Ru and Os clusters, 6, 727 Imidazo[l,2-a]-pyridines, iodo-substituted, in Grignard reagent preparation, 9, 37—38 Imido alkyl complexes, with tantalum, 5, 118—120 Imido-amido half-sandwich compounds, with tantalum, 5,183 /13-Imido clusters, with trinuclear Ru clusters, 6, 733 Imido complexes with bis-Gp Ti, 4, 579 with monoalkyl Ti(IV), 4, 336 with mono-Gp Ti(IV), 4, 419 with Ru half-sandwiches, 6, 519—520 with tantalum, 5, 110 with titanium(IV) dialkyls, 4, 352 with titanocenes, 4, 566 with tungsten... 

Substituted imidazo[4,5-c]pyridin-2-ones such as compound (149) upon reaction with iodo-methane gave intractable mixtures rather than the desired product (150). To prepare compound (150) one must first /V-alkylate the imidazole (151) and subsequently annulate <93JMC1341>. 

An interesting study of conformationally mobile systems involves iodo-methylation of nicotine derivatives 47, where steric effects of substituents at position-2 and -6 modify the alkylation rate at the pyridine nitrogen and at the two nitrogens (N trans and N cis) of the pyrrolidine conformers (80JA7741 81JOC3040) (Scheme 26b). 

The preparation of 5 -alkyl- and 5 aryl-oestra-l(10),4-dieno[3,26)]furans (96) by treatment of 2-iodo-oestrone (95) or oestradiol with the corresponding Cu acetylides in boiling pyridine has been reported. 

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. 

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