4,4 -Bromomethyl-2,2 -bipyridine

Examples of amino acids with bipyridine units on the peptide side chain are also known.274 The 6-bromomethyl bipyridine has been used in the stereoselective synthesis and incorporation of an amino acid with a bipyridine binding site into short peptide chains.275 The ligand (5)-2-amino-3-(2,2 -bipyridin- -yl)propanoic acid, where n = 4-6,276 has been prepared in 98% ee.277... 

Reagents (a) (CHaOln, HBr, HOAc (b)4,4 -bipyridine, CH3CN (c) 1,3-bis(bromomethyl)benzene, aq. CH3NO2... 

Geren L, Hahm S, Durham B, Millett F. Photoinduced electron transfer between cytochrome c peroxidase and yeast cytochrome c labeled at Cys 102 with (4-bromomethyl-4 -methylbipyridine)[bis(bipyridine)]ruthenium2+. Biochemistry 1991 30 9450-7. 

The ruthenium complexes were attached to the specified cysteine by formation of a thioether linkage between the sulfur atom of cysteine and the methylene carbon of one of the bipyridine ligands. The reaction makes use of complexes that contain 4-bromomethyl-4 -methylbipyridine, as indicated. 

Prepare a solution of SSNa (23.0 mmol), methyl-4-(bromomethyl) benzoate (initiator I, 0.332 mmol), copper (I) bromide (0.33 mmol) and 2,2 -bipyridine (0.66 mmol) in a methanol/water (50/50) solution in a dry round-bottom flask. Stir the reaction mixture at 25 °C. After 24 h, precipitate the product using tetrahydrofuran and dry under vacuum. 

In addition to the commercially available 4,4 -bipyridine, gram quantities of 3,4 - and 3,3 -bipyridines have also been made by cross-coupling reac-tions." Bromomethyl phenylboronic acid or benzyl bromide was reacted in dimethylformamide with the corresponding bipyridines to obtain the desired viologens. The products were isolated by precipitation from acetone (Figure 5.9). 

The synthesis of a molecule containing two 5,5 -disubstituted-2,2 -bipyridyl units was achieved by the reaction of two equivalents of 5-bromomethyl-5 -methyl 2,2 -bipyridine (1) [11] with N,N -dimethylethylene diamine (2) in acetonitrile using potassium carbonate as base. Purification by column chromatography on alumina, using CH Cl /MeOH (99 1) as eluent, and recrystallisation from acetonitrile afforded (3) in 43% yield (Scheme 1). Reaction of (3) with dimethyl sulphate at 75 C for 7 days gave a mixture of products that were not fully methylated. Following conversion to the hexafiuorophosphate salts, this mixture was reacted further with methyl iodide in acetonitrile at reflux for 18 days. After this tii e the product was isolated and converted to the hexa-hexafluorophosphate salt to give L in 11% overall yield (Scheme 1). 

Reaction of 5,5 -bis(bromomethyl)-2,2 -bipyridine (4) [11] with a large excess of 4,4-bipyridine (5) in acetonitrile, followed by conversion of the resultant precipitate to the hexafiuorophosphate salt, gave the dicationic compound (6) in 88% yield (Scheme 2). The reaction of (6) with methyl iodide in nitromethane at reflux for 24h produced an orange precipitate which was collected, dissolved in water and converted to the hexafiuorophosphate salt to afford the tetra-cationic compound (7) in 89% yield (Scheme 2). Alkylation of (7) with dimethyl sulphate in acetonitrile at reflux for 48h gave initially a white precipitate hich was converted to the hexa-cationic hexafiuorophosphate acyclic receptor molecule L in 71% yield (Scheme 2). 

Bipyridine (5) was reacted with two equivalents of 5-bromomethyl-5 -methyl-2,2 -bipyridine (1) to produce, on addition of ammonium hexafiuorophosphate, the dicationic compound (8) in 78% yield (Scheme 3). Exhaustive methylation of (8) was achieved via alkylation reactions with methyl iodide and subsequently dimethyl sulphate followed finally by conversion to the hexafiuorophosphate salt to give the desired hexa-cationic receptor L in 44% overall yield. (Scheme 3). All these new acyclic receptors gave spectroscopic and analytical data in accordance with assigned structures. 

Bipyridines were synthesized by thiolatedeprotection with cesium hydroxide and reaction withhalogenides R-CH2-Br, performing the last step in Figure 13.25 with 5,5 -bis(bromomethyl)-2,2 -bipyridine and 4,4 -bis(bromobutyl)-2,2 -bipyridine. i The metal complexes depicted in Figure 13.26 were synthesized with [Ru(bipy)2Cl2], RuClj, and FeS04, respectively ... 

A new 2,2 -bipyridine-based 15-membered phosphadithiamacrocycle 150 has been synthesized by the reaction of 6,6 -bis(bromomethyl)-2,20-bipyridine and dilithium 3-phenyl-3-phosphapenta-l,5-dithiolate under high-dilution (Scheme 12.56). The phosphoryl derivative 151 was synthesized by direct oxidation of 150 at open atmosphere. The reaction of 150 and 151 with Fe(II) perchlorate gave the complexes 152 (X = lone pair, O). In both cases, a distorted octahedral environment is achieved at the Fe(II), with five sites occupied by the macrocycles 150 and 151 and the sixth by a monodentate bromine ligand. The bond distances found in the complex cation 152 (X = O) are compatible with a high-spin... 

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