2005
DOI: 10.1016/j.tet.2004.10.097
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Highly functionalised organolithium and organoboron reagents for the preparation of enantiomerically pure α-amino acids

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Cited by 53 publications
(33 citation statements)
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“…Flash chromatography of the crude product revealed the presence of p-toluenesulphonamide and other side products, probably arising from a β-elimination reaction on the corresponding dilithium intermediate. The same results were observed, by using different solvents (THF, ether), temperatures (−78, −20, 0 ºC, r.t,), additives such HMPA, TMEDA and LiNp (lithium naphtalenide 19 ), as well as t-BuLi. Based on these unsucessful results obtained with the β-tellurium amines derived from L-phenylalanine in Te/Li exchange reactions, we decided to evaluate the behaviour of a very simple class of β-tellurium amines, containing different protecting groups (PG = Boc, Cbz, Bz and Ts) and only a C2 carbon chain between the tellurium and nitrogen moieties, aiming to minimize the possibility of β-elimination.…”
supporting
confidence: 78%
“…Flash chromatography of the crude product revealed the presence of p-toluenesulphonamide and other side products, probably arising from a β-elimination reaction on the corresponding dilithium intermediate. The same results were observed, by using different solvents (THF, ether), temperatures (−78, −20, 0 ºC, r.t,), additives such HMPA, TMEDA and LiNp (lithium naphtalenide 19 ), as well as t-BuLi. Based on these unsucessful results obtained with the β-tellurium amines derived from L-phenylalanine in Te/Li exchange reactions, we decided to evaluate the behaviour of a very simple class of β-tellurium amines, containing different protecting groups (PG = Boc, Cbz, Bz and Ts) and only a C2 carbon chain between the tellurium and nitrogen moieties, aiming to minimize the possibility of β-elimination.…”
supporting
confidence: 78%
“…6,7) The efficient synthesis of photoactivatable optically pure hPhe is important for this. Although several synthetic protocols for optically active hPhe have been reported by various method including enzymatic resolution, 8) Suzuki-coupling, 9) diastereoselective Michael addition 10) and catalytic asymmetric hydrogenation, 11) these required special reagents or precursors. It might not be sutable to apply those for the preparation of diazirinylated hPhe, because some conditions might reduce the diazirine function.…”
mentioning
confidence: 99%
“…[41] With 5 mol-% Pd(OAc) 2 and 25 mol-% PPh 3 , coupling products with bromobenzene, 2-bromonaphthalene, 4-bromonitrobenzene or bromopyridines were obtained in good yields (Scheme 26). Scheme 26. The Suzuki-Miyaura alkylation method has also been employed for the synthesis of several compounds, such as for the methylation of Binap derivatives, [42,43] the alkylation of pyrimidines, [44] the preparation of enantiopure α-amino acids, [45,46] or the synthesis of natural [47] and biologically active compounds. [48] In summary, Suzuki-Miyaura cross-coupling alkylation of aryl halides with primary alkylboronic acids is now a powerful method for the synthesis of alkylarenes.…”
Section: Methodsmentioning
confidence: 99%