- Ligand-Enabled β-C–H Arylation of α-Amino Acids Without Installing Exogenous Directing Groups
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Herein we report acid-directed β-C(sp3)-H arylation of α-amino acids enabled by pyridine-type ligands. This reaction does not require the installation of an exogenous directing group, is scalable, and enables the preparation of Fmoc-protected unnatural amino acids in three steps. The pyridine-type ligands are crucial for the development of this new C(sp3)-H arylation.
- Chen, Gang,Zhuang, Zhe,Li, Gen-Cheng,Saint-Denis, Tyler G.,Hsiao, Yi,Joe, Candice L.,Yu, Jin-Quan
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supporting information
p. 1506 - 1509
(2017/02/05)
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- Substituent effect on the stereoselectivity of acylation of racemic heterocyclic amines with N-phthaloyl-3-aryl-(S)-alanyl chlorides
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The acylative kinetic resolution of racemic 2-methyl-1,2,3,4- tetrahydroquinoline and 2,3-dihydro-3-methyl-4H-1,4-benzoxazine using acyl chlorides of N-phthaloyl-(S)-phenylalanine, N-phthaloyl-3-(4-nitrophenyl)-(S)- alanine and N-phthaloyl-O-methyl-(S)-tyrosine as chiral resolving agents has been carried out. It is shown that the effectiveness of an acylative kinetic resolution depends on the electronic effects of substituents in the phenyl fragment of the acylating agent and increases as the electron-donating properties of the para-substituent (OMe > H > NO2) in phenyl fragment of N-phthaloyl-3-aryl-(S)-alanyl chlorides increase; conducting the process at a reduced temperature also contributes to an enhancement of the kinetic resolution.
- Levit, Galina L.,Gruzdev, Dmitry A.,Krasnov, Victor P.,Chulakov, Evgeny N.,Sadretdinova, Liliya Sh.,Ezhikova, Marina A.,Kodess, Mikhail I.,Charushin, Valery N.
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experimental part
p. 185 - 189
(2011/04/26)
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- Intramolecular Friedel-Crafts Acylation of N-Phthaloyl-Substituted Arylalanyl and Homophenylalanyl Chlorides
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N-Phthaloyl-protected arylalanyl and homophenylalanyl chlorides 5 are acylated intramolecularly to 2-phthalimido-1-indanones 6 and -1-tetralone (6d) with AlCl3 (two-fold molar amounts) or catalytic amounts of FeCl3.The cycloacylation to the tetralone 6d with AlCl3 or FeCl3 proceeds without racemisation in very good yields, whereas the cycloacylation to the indanone 6a with FeCl3 gives rise to racemisation.Mixed anhydrides 11 of N-phthaloyl-α-amino acids and trifluoromethanesulfonate were prepared from the N-phthaloylamino acid chlorides and silver triflate.Acylation of arenes 12 with 11a as well as cycloaddition of (S)-O-methyl-N-phthaloyltyrosine triflate can be achieved without racemisation and without a catalyst.
- Effenberger, Franz,Steegmueller, Dieter,Null, Volker,Ziegler, Thomas
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p. 125 - 130
(2007/10/02)
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