99275-46-4Relevant articles and documents
Deprotonative metalation of five-membered aromatic heterocycles using mixed lithium-zinc species
L'Helgoual'ch, Jean-Martial,Seggio, Anne,Chevallier, Floris,Yonehara, Mitsuhiro,Jeanneau, Erwann,Uchiyama, Masanobu,Mongin, Florence
, p. 177 - 183 (2008/09/17)
(Equation Presented) Deprotonation of benzoxazole, benzothiazole, benzo[b]thiophene, benzo[b]furan, N-Boc-protected indole and pyrrole, and N-phenylpyrazole using an in situ mixture of ZnCl2·TMEDA (0.5 equiv) and lithium 2,2,6,6-tetramethylpipe
An aluminum ate base: Its design, structure, function, and reaction mechanism
Naka, Hiroshi,Uchiyama, Masanobu,Matsumoto, Yotaro,Wheatley, Andrew E. H.,McPartlin, Mary,Morey, James V.,Kondo, Yoshinori
, p. 1921 - 1930 (2007/10/03)
An aluminum ate base, i-Bu3Al(TMP)Li, has been designed and developed for regio- and chemoselective direct generation of functionalized aromatic aluminum compounds. Direct alumination followed by electrophilic trapping with I2, Cu/Pd-catalyzed C-C bond formation, or direct oxidation with molecular O2 proved to be a powerful tool for the preparation of 1,2- or 1,2,3-multisubstituted aromatic compounds. This deprotonative alumination using i-Bu3Al(TMP)Li was found to be effective in aliphatic chemistry as well, enabling regio- and chemoselective addition of functionalized allylic ethers and carbamates to aliphatic and aromatic aldehydes. A combined multinuclear NMR spectroscopy, X-ray crystallography, and theoretical study showed that the aluminum ate base is a Li/Al bimetallic complex bridged by the nitrogen atom of TMP and the α-carbon of an i-Bu ligand and that the Li exclusively serves as a recognition point for electronegative functional groups or coordinative solvents. The mechanism of directed ortho alumination reaction of functionalized aromatic compounds has been studied by NMR and in situ FT-IR spectroscopy, X-ray analysis, and DFT calculation. It has been found that the reaction proceeds with facile formation of an initial adduct of the base and aromatic, followed by deprotonative formation of the functionalized aromatic aluminum compound. Deprotonation by the TMP ligand rather than the isobutyl ligand was suggested and reasoned by means of spectroscopic and theoretical study. The remarkable regioselectivity of the ortho alumination reaction was explained by a coordinative approximation effect between the functional groups and the counter Li+ ion, enabling stable initial complex formation and creation of a less strained transition state structure.
Regio- and chemoselective direct generation of functionalized aromatic aluminum compounds using aluminum ate base
Uchiyama, Masanobu,Naka, Hiroshi,Matsumoto, Yotaro,Ohwada, Tomohiko
, p. 10526 - 10527 (2007/10/03)
A regio- and chemoselective direct method for generation of functionalized aromatic aluminum compounds through deprotonative directed ortho-alumination using triisobutyl(tetramethylpiperidino)aluminate (iBu3Al(TMP)Li), prepared by mixing of triisobutylaluminum (iBu3Al) and lithium tetramethylpiperidide (LTMP) in THF, has been developed. Deprotonative alumination of various functionalized benzenes with the use of iBu3Al(TMP)Li proved effective for the direct generation of various ortho-functionalized aluminum aromatic and heteroaromatic derivatives, particularly those with electrophilic functional groups such as cyano, amide, and halogen. Direct alumination, followed by electrophilic trapping (with I2), provided a convenient preparative method for 1,2- or 1,2,3-multisubstituted aromatic compounds. The functionalized aromatic aluminate intermediate also was found to undergo copper- and palladium-catalyzed C-C bond-forming reactions very efficiently and highly regio- and chemoselectively. Copyright
