Synthesis of the biaryl moiety of the proteasome inhibitors TMC-95 via a ligandless Pd(OAc)2-catalyzed Suzuki-coupling reaction
The biaryl moiety of proteasome inhibitors TMC-95 was synthesized via a Pd(OAc)2-catalyzed Suzuki-coupling reaction of 7-iodoisatin and a tyrosine-derived arylboronic acid in the absence of phosphine ligands using potassium fluoride as a base.
Chiral sensors for determining the absolute configurations of α-amino acid derivatives
A simple strategy for configurational assignments of alpha-amino acids has been developed by comparison of the proton NMR chemical shift values of the alpha hydrogens of N-phthaloyl protected alpha-amino acids in the presence of (R)-CSA 1 and (S)-CSA 1, respectively. Highly resolved NMR spectra can be obtained directly on the mixed solution of the chiral solvating agents with N-phthaloyl protected alpha-amino acids in NMR tubes, giving well distinguishable proton signals without interference which dramatically improve the accuracy of assignment and hasten the assigning procedure. The strategy is widely applicable for varied natural and non-natural amino acids.
Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine: Histidine and tryptophan
The photochemistry of phthalimide derivatives of the electron-rich amino acids tyrosine, histidine and tryptophan 8-10 was studied with respect to photoinduced electron-transfer (PET)induced decarboxylation and Norrish II bond cleavage. Whereas exclusive photodecarboxylation of the tyrosine substrate 8 was observed, the histidine compound 9 resulted in a mixture of histamine and preferential Norrish cleavage. The tryptophan derivative 10 is photochemically inert and shows preferential decarboxylation only when induced by intermolecular PET.
Griesbeck, Axel G.,Neudoerfl, Joerg,Kiff, Alan De
experimental part
p. 518 - 524
(2011/06/28)
An expeditious approach for the synthesis of β-hydroxy aryl α-amino acids present in vancomycin
Stereoselective synthesis of the β-hydroxyaryl amino acids which constitute C and E rings of vancomycin is described making use of benzylic oxidation and asymmetric dihydroxylation as the key steps.
Rama Rao,Chakraborty,Laxma Reddy,Srinivasa Rao
p. 5043 - 5046
(2007/10/02)
SYNTHESIS OF HOMOCHIRAL HYDROXY-α-AMINO ACID DERIVATIVES
Treatment of N-phthaloyl-α-amino acid methyl esters with N-bromosuccinimide, followed by reaction with silver nitrate in aqueous acetone, affords homochiral hydroxy-α-amino acid derivatives, the stereochemistry of which is predetermined by that of the starting amino acids.
Easton, Christopher J.,Hutton, Craig A.,Tan, Eng Wui,Tiekink, Edward R. T.
p. 7059 - 7062
(2007/10/02)
Circular dichroism and configuration of alpha-amine acids
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Auterhoff,Hansen
p. 336 - 340
(2007/10/04)
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