- Unnatural tripeptide as highly enantioselective organocatalyst for asymmetric aldol reaction of isatins
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The development of unnatural tripeptides as highly enantioselective organocatalysts for the asymmetric aldol reaction of isatins was achieved. H-Pro-Gly-D-Ala-OH with the D-alanine residue as the C-terminal amino acid residue expressed the best enantioselectivity. The H-Pro-Gly-D-Ala-OH-catalyzed reaction of isatins gave various aldol adducts with up to 93% yield and up to 97% ee. Investigation of the transition state via DFT calculation revealed that high optical purity was realized by the D-alanine controlled steric environment.
- Kon, Kazumasa,Kohari, Yoshihito,Murata, Miki
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- Organocatalyzed Asymmetric Aldol Reaction of α-Keto Amides with A Tripeptide Catalyst
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An organocatalyzed asymmetric aldol reaction of α-keto amides was developed. An N-terminal 4- trans -siloxyproline-based tripeptide with an l - tert -leucine unit adjacent to the 4- trans -siloxyproline residue was used to catalyze the reaction between various α-keto amides and acetone, to produce the corresponding aldol adducts with up to 99% yield and 91% ee.
- Kon, Kazumasa,Takai, Hiromu,Kobayashi, Takumu,Kohari, Yoshihito,Murata, Miki
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supporting information
p. 829 - 832
(2021/02/26)
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- Efficient peptide coupling involving sterically hindered amino acids
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(Chemical Equation Presented) Hindered amino acids have been introduced into peptide chains by coupling N-(Cbz- and Fmoc-α-aminoacyl) benzotriazoles with amino acids, wherein at least one of the components was sterically hindered, to provide compounds 3a-e, (3c +3 c′), 5a-d, (5a + 5a′), 6a-c, (6b + 6b′), 8a-c, 9a-e, 10a-d, and (10a + 10a′) in isolated yields of 41-95% with complete retention of chirality as evidenced by NMR and HPLC analysis. The benzotriazole activation methodology is a new route for the synthesis of sterically hindered peptides. (Note: compound numbers written within brackets represent diastereomeric mixtures or racemates; compound numbers without brackets represent enantiomers.)
- Katritzky, Alan R.,Todadze, Ekaterina,Angrish, Parul,Draghici, Bogdan
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p. 5794 - 5801
(2008/02/09)
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