95881-80-4Relevant articles and documents
Deprotonative metalation of aromatic compounds using mixed lithium-iron combinations
Nagaradja, Elisabeth,Chevallier, Floris,Roisnel, Thierry,Jouikov, Viatcheslav,Mongin, Florence
experimental part, p. 3063 - 3073 (2012/06/01)
The deprotonation of 2-methoxypyridine was attempted using putative (TMP)3FeLi prepared from different iron sources. Using iodine to intercept the metalated 2-methoxypyridine, the best result was obtained from FeBr2 (1 equiv) using THF at room temperature; nevertheless, in addition to the expected iodide, the corresponding 2,2′-dimer was obtained (86% total yield). The origin of the competitive formation of the 2,2′-dimer was not identified but mechanisms were suggested to explain its formation. It was observed that the nature of the electrophile employed to trap the 3-metalated 2-methoxypyridine has a strong impact on this dimer formation, the latter being favored using iodine (35% yield), but also benzophenone (28%), benzoyl chloride (22%), methyl iodide (27%), allyl bromide (15%), benzyl bromide (41%), and tetramethylthiuram disulphide (36%); for this reason, the yields of the expected derivatives were only 51, 15, 62, 0, 5, 18, and 0%, respectively. In contrast, using aldehydes readily led to the expected pyridine alcohols without dimerization (59% yield using 3,4,5-trimethoxybenzaldehyde and 66% yield using pivalaldehyde). 2,6-Dimethoxypyridine (in 68% yield), anisole (47%), 2,4-dimethoxypyrimidine (50% at C5 and 3% at C6), 2-fluoropyridine (64%), and thiophene (49%) were similarly converted into the corresponding alcohols after subsequent trapping with pivalaldehyde. Using iodine to trap the 2-metalated anisole did not lead to dimer formation, and 2-iodoanisole was isolated in 71% yield.
Deprotonative metalation of aromatic compounds by using an amino-based lithium cuprate
Nguyen, Tan Tai,Marquise, Nada,Chevallier, Floris,Mongin, Florence
experimental part, p. 10405 - 10416 (2011/10/12)
Deprotonative cupration of aromatic compounds by using amino-based lithium cuprates was optimized with 2,4-dimethoxypyrimidine and 2-methoxypyridine as the substrates and benzoyl chloride as the electrophile. [(tmp)2CuLi] (+2 LiCl) (tmp=2,2,6,6-tetramethylpiperidino) was identified as the best reagent and its use was extended to anisole, 1,4-dimethoxybenzene, other substituted pyridines, furan, thiophene and derivatives, and N-Boc-indole (Boc=tert-butyloxycarbonyl). Of the electrophiles employed to attempt the interception of the generated aryl cuprates, aroyl chlorides, iodomethane, and diphenyl disulfide efficiently reacted. In addition, different oxidative agents were identified to afford symmetrical biaryls. Finally, palladium-catalyzed coupling with aryl halides was optimized and allowed the synthesis of different aryl derivatives in medium to good yields.
Deprotonative metalation of substituted aromatics using mixed lithium-cobalt combinations
Dayaker, Gandrath,Chevallier, Floris,Gros, Philippe C.,Mongin, Florence
experimental part, p. 8904 - 8910 (2011/01/04)
The deprotonation of anisole was attempted using different homo- and heteroleptic TMP/Bu mixed lithium-cobalt combinations. Using iodine to intercept the metalated anisole, an optimization of the reaction conditions showed that in THF at room temperature 2 equiv of base were required to suppress the formation of the corresponding 2,2′-dimer. The origin of the dimer was not identified, but its formation was favored with allyl bromide as electrophile. The metalated anisole was efficiently trapped using iodine, anisaldehyde, and chlorodiphenylphosphine, and moderately employing benzophenone, and benzoyl chloride. 1,2-, 1,3-, and 1,4-dimethoxybenzene were similarly converted regioselectively to the corresponding iodides. It was observed that 2-methoxy- and 2,6-dimethoxypyridine were more prone to dimerization than the corresponding benzenes when treated similarly. Involving ethyl benzoate in the metalation-iodination sequence showed that the method was not suitable to functionalize substrates bearing reactive functions.
Syntheses of Hydroxylated Bipyridines, III. - Synthesis of Unsymmetrically and Symmetrically Structured Dihydroxybipyridines
Dehmlow, Eckehard V.,Sleegers, Arthur
, p. 953 - 960 (2007/10/02)
Fifteen symmetrical and asymmetrical dimethoxybipyridines and the pertinent diols are prepared and characterized.Reductive cross coupling of halopyridines with Ni(0) may result in complex mixtures.The same is true for an alternative reaction of (trimethylstannyl)pyridines with halopyridines in the presence of Pd(0).UV, 1H-, and 13C-NMR spectra of the bipyridine derivatives are tabulated.Key Words: Bipyridinediols / Pyridines / Stannylpyridines
