- Total Synthesis of cis-Clavicipitic Acid from Asparagine via Ir-Catalyzed C-H bond Activation as a Key Step
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4-Substituted tryptophan derivatives and the total synthesis of cis-clavicipitic acid were achieved in reactions in which Ir-catalyzed C-H bond activation was a key step. The starting material for these reactions is asparagine, which is a cheap natural amino acid. The reductive amination step from the 4-substituted tryptophan derivative gave cis-clavicipitic acid with perfect diastereoselectivity.
- Tahara, Yu-Ki,Ito, Mamoru,Kanyiva, Kyalo Stephen,Shibata, Takanori
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p. 11340 - 11343
(2015/08/03)
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- A direct route to 2,2,5-trisubstituted pyrrolidines of relevance to kaitocephalin
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2,2,5-Trisubstituted pyrrolidines of relevance to the core of kaitocephalin are readily available by an oxime ring closure using substrates derived from aspartic acid.
- Chandan, Nandkishkor,Moloney, Mark G.
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supporting information
p. 1987 - 1990
(2013/04/10)
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- An access to aza-Freidinger lactams and E-locked analogs
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Freidinger lactams, possessing a peptide bond configuration locked to Z, are important key elements of conformationally restricted peptidomimetics. In the present work, the CαHi+1 unit has been replaced by N, leading to novel aza-Fre
- Ottersbach, Philipp A.,Schmitz, Janina,Schnakenburg, Gregor,Gütschow, Michael
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p. 448 - 451
(2013/04/11)
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- A PREPARATION METHOD OF SITAGLIPTIN
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The present invention relates to a preparation method of sitagliptin, and more particularly, to a method of preparing sitagliptin using L-aspartic acid having a (R)-beta amino acid structure by mild amide formation, by the use of industrially applicable halo isopropylmagnesium, and by removal of amine protecting group using Pd/C and H2 and carbonyl reduction using reducing agent.
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Page/Page column 13
(2012/11/13)
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- A versatile and selective chemo-enzymatic synthesis of β-protected aspartic and γ-protected glutamic acid derivatives
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Two versatile, high yielding, and efficient chemo-enzymatic methods for the synthesis of β-protected Asp and γ-protected Glu derivatives using Alcalase are described. The first method is based on the α-selective enzymatic hydrolysis of symmetrical aspartyl and glutamyl diesters. The second method involving mixed diesters comprises a three-step protocol using (i) α-selective enzymatic methyl-esterification, (ii) chemical β-esterification, and finally (iii) α-selective enzymatic methyl ester hydrolysis. The yields of the purified β- and γ-esters range from 77% to 91%.
- Nuijens, Timo,Kruijtzer, John A.W.,Cusan, Claudia,Rijkers, Dirk T.S.,Liskamp, Rob M.J.,Quaedflieg, Peter J.L.M.
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experimental part
p. 2719 - 2721
(2009/09/06)
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- Utility of tetrathiomolybdate and tetraselenotungstate: Efficient synthesis of cystine, selenocystine, and their higher homologues
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Efficient synthesis of cystine, selenocystine, and their higher homologues like homo and bishomo amino acid derivatives from natural amino acid derivatives using tetrathiomolybdate and tetraselenotungstate reagents under mild and neutral conditions is reported. The generality of the reaction has been studied by capping various groups to amino and carboxyl components of canonical amino acids.
- Bhat, Ramakrishna G.,Porhiel, Emmanuel,Saravanan, Vadivelu,Chandrasekaran, Srinivasan
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p. 5251 - 5253
(2007/10/03)
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- The Preference Profile in Ruthenium Tetroxide Oxidations
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The preference profile of RuVIII-generated in a catalytic cycle, maintained by periodate in carbon tetrachloride : acetonitrile : water -has been examined from a practical vantage using tyrosine, phenylalanine and lysine as primary substrates. Other factors such as pH, acetonitrile versatility, transport of oxidized ruthenium species across the layers and hydrophobic alignment, influence the course of the reaction. Aryl oxidation, which takes place at the organic interface, is strongly influenced by ring perturbation (pOH-C6H4CH2CH,++; PhCH2CH,+, PhCH2O,+; PhCH2OCONH(Z),-; PhCH2OCO,-; pOH-C6H4CH2CO,+; PhCH2CO,-; PhCO,-). In the case of tyrosine, the preference profile switches from ring oxidation at pH 3 to α-amino group oxidation at pH 6 and 9, whilst with phenylalanine, the amino group is exclusively oxidized even at pH 3. With lysine, the reasonable differences in pKa between the α-amino group (8.95) and the ω-amino unit (10.53), elicit sharp preferences. At pH 3 as well as at 6, the α-amino group is selectively oxidized leading to glutaric acid mono-amide, a finding supported by studies with Nα and Nω protected lysines. Lysine and arginine side-chains are found largely unaffected by the reagent at pH 3 and 6. The findings have been rationalized on the basis of an integrated mechanism. The work has endeavoured to reconcile seemingly conflicting reports in the literature and to project the reagent for selective modifications in synthesis.
- Ranganathan,Muraleedharan,Bhattacharyya,Kundu
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p. 583 - 589
(2007/10/03)
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- Synthesis of (3R)- and (3S)-3,4-diamino-butyric acid from L-aspartic acid
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A short and convenient synthesis for both enantiomers of GABOB amino-analogue 1a,b is reported, starting from L-aspartic acid. The protected diester 3 is the common intermediate for the synthetic pathway.
- Misiti,Santaniello,Zappia
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p. 883 - 891
(2007/10/02)
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- The transformation of histidine side chain to non-coded asparagines
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The transformation of the histidine side chain to that of Nω-carbamoyl asparagine, Nω-formyl asparagine, Nω-benzoyl asparagine, β-cyano alanine and aspartic acid has been described, involving as the primary step, the Ru(VI
- Ranganathan, Subramania,Ranganathan, Darshan,Bhattacharyya, Dipti
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p. 5615 - 5618
(2007/10/02)
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- MONO-ESTERIFICATION OF N-PROTECTED DI-ACIDS ASPARTIC AND GLUTAMIC BY CHLOROFORMATE ACTIVATION
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Mono-esters of N-protected di-acids aspartic and glutamic are prepared by a one-pot activation with alkyl chloroformates or isopropenyl chloroformate and an additionnal alcohol.This process involves the intermediate internal anhydride formation.
- Jouin, P.,Castro, B.,Zeggaf, C.,Pantaloni, A.,Senet, J.P,et al
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p. 1665 - 1668
(2007/10/02)
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- The Transformation of Tryptophan to Aspartic Acid in Peptides
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The tryptophan side chain is transformed by in situ generated ruthenium(VIII), to that of aspartic acid, in good yields; amulti-step degradation sequence is suggested on the basis of the transformations of tetrahydrocarbazole to adipic acid, valine to isobutyric acid, and phenylalanine to phenylacetic acid.
- Ranganathan, Subramania,Ranganathan, Darshan,Bhattacharyya, Dipti
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p. 1085 - 1086
(2007/10/02)
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