- Asymmetric synthesis of α-amino acids via chiral N-alkylidenesulfinamides
-
(SR)-(-)-N-[1-(Triethoxymethyl)ethylidene]-p-toluenesulfonamide (2) was synthesized from the addition reaction of triethoxyacetonitrile with MeLi followed by (+)-(R)-d-menthyl-p-toluenesulfinate (1R). Sulfinimine 2 underwent complete stereoselective reduc
- Hua,Lagneau,Wang,Chen
-
-
Read Online
- Palladium-catalyzed asymmetric decarboxylative allylation of azlactone enol carbonates: Fast access to enantioenriched α-allyl quaternary amino acids
-
We report a fast protocol for the synthesis of enantioenriched quaternary 4-allyl oxazol-5-ones. The key step is a Pd-catalyzed enantioselective Tsuji allylation of azlactone allyl enol carbonates, which can be easily prepared starting from racemic α-amino acids. The use of (R,R)-DACH-phenyl Trost chiral ligand allowed the attainment of the allylated derivatives in very good yields (83–98 %) and with ee up to 85 %. Scaling up the allylation protocol to gram quantities did not affect the yields end ee values. The produced 4-allyl azlactones can be converted into the corresponding quaternary amino acids or submitted to further synthetic elaborations exploiting the allyl moiety as a handle for the attachment of alkyl and aryl groups. After hydrolysis of the azlactone ring, the zwitterionic amino acids can be attained in enantiopure or nearly optically pure form through only one recrystallization step.
- Serra, Massimo,Bernardi, Eric,Marrubini, Giorgio,De Lorenzi, Ersilia,Colombo, Lino
-
p. 732 - 741
(2019/01/09)
-
- High-chirality method for selectively synthesizing alpha-disubstituted alpha-amino acid
-
The invention discloses a high-chirality method for selectively synthesizing alpha-disubstituted alpha-amino acid. The high-chirality method for selectively synthesizing alpha-disubstituted alpha-amino acid is characterized by comprising the following steps: step one, reacting S-tert-butanesulfinyl amide or R-tert-butanesulfinyl amide, R-beta substituted ethyl pyruvate and tetraethyl titanate in atetrahydrofuran solvent to obtain a compound C; step two, reacting the compound C with alkyl substituted magnesium bromide under the catalyzing effect of zinc dimethyl in tetrahydrofuran to obtain acompound E; step three, reacting the compound E under the effect of ammonium chloride and anhydrous hydrogen chloride to obtain a compound F; and step four, hydrolyzing the compound F in an ethanol aqueous solution of sodium hydroxide to obtain hydrochloride of a compound G, and carrying out ion exchange to obtain the compound G. The chiral selective reaction is greatly improved, and the method issimple in process, uses cheap and easily obtained raw materials, is simple and convenient to operate, is quite suitable for industrial mass production, and has quite extensive industrial applicationprospect and market value.
- -
-
Paragraph 0045; 0047; 0054
(2018/09/13)
-
- METHOD FOR SYNTHESIZING OPTICALLY ACTIVE a-AMINO ACID USING CHIRAL METAL COMPLEX COMPRISING AXIALLY CHIRAL N-(2-ACYLARYL)-2-[5,7-DIHYDRO-6H-DIBENZO[c,e]AZEPIN-6-YL] ACETAMIDE COMPOUND AND AMINO ACID
-
Objects of the present invention are to provide an industrially applicable method for producing an optically active α-amino acid in high yield and in a highly enantioselective manner, to provide a simple production method of an optically active α,α-disubstituted α-amino acid, and to provide an intermediate useful for the above production methods of an optically active α-amino acid and an optically active α,α-disubstituted α-amino acid. The present invention provides a production method of an optically active α-amino acid or a salt thereof, the production method comprising introducing a substituent into the α carbon in the α-amino acid moiety of a metal complex represented by the following Formula (1): by an alkylation reaction, an aldol reaction, the Michael reaction, or the Mannich reaction, and releasing an optically pure α-amino acid enantiomer or a salt thereof by acid decomposition of the metal complex.
- -
-
Paragraph 0439-0446
(2016/05/10)
-
- METHOD FOR SYNTHESIZING OPTICALLY ACTIVE α-AMINO ACID USING CHIRAL METAL COMPLEX COMPRISING AXIALLY CHIRAL N-(2-ACYLARYL)-2-[5,7-DIHYDRO-6H-DIBENZO[c,e]AZEPIN-6-YL]ACETAMIDE COMPOUND AND AMINO ACID
-
Objects of the present invention are to provide an industrially applicable method for producing an optically active ±-amino acid in high yield and in a highly enantioselective manner, to provide a simple production method of an optically active ±,±-disubstituted ±-amino acid, and to provide an intermediate useful for the above production methods of an optically active ±-amino acid and an optically active ±,±-disubstituted ±-amino acid. The present invention provides a production method of an optically active ±-amino acid or a salt thereof, the production method comprising introducing a substituent into the ± carbon in the ±-amino acid moiety of a metal complex represented by the following Formula (1): by an alkylation reaction, an aldol reaction, the Michael reaction, or the Mannich reaction, and releasing an optically pure ±-amino acid enantiomer or a salt thereof by acid decomposition of the metal complex.
- -
-
Paragraph 0748; 0750-0752; 0763
(2016/11/17)
-
- Influence of α-methylation in constructing stapled peptides with olefin metathesis
-
Ring-closing metathesis is commonly utilized in peptide macro-cyclization. The influence of α-methylation of the amino acids bearing the olefin moieties has never been systematically studied. In this report, controlled reactions unambiguously indicate that α-methylation at the N-terminus of the metathesis sites is crucial for this reaction to occur. Also, we first elucidated that the E-isomers of stapled peptides are significantly more helical than the Z-isomers.
- Zhang, Qingzhou,Shi, Xiaodong,Jiang, Yanhong,Li, Zigang
-
p. 7621 - 7626
(2014/12/11)
-
- Synthesis of quaternary α-methyl α-amino acids by asymmetric alkylation of pseudoephenamine alaninamide pivaldimine
-
The utility of pseudoephenamine as a chiral auxiliary for the alkylative construction of quaternary α-methyl α-amino acids is demonstrated. The method is notable for the high diastereoselectivities of the alkylation reactions, for its versatility with respect to electrophilic substrate partners, and for its mild hydrolysis conditions, which provide α-amino acids without salt contaminants. Alternatively, α-amino esters can be obtained by direct alcoholysis.
- Hugelshofer, Cedric L.,Mellem, Kevin T.,Myers, Andrew G.
-
supporting information
p. 3134 - 3137
(2013/07/26)
-
- Microbial whole cell-catalyzed desymmetrization of prochiral malonamides: Practical synthesis of enantioenriched functionalized carbamoylacetates and their application in the preparation of unusual α-amino acids
-
Catalyzed by Rhodococcus erythropolis AJ270, an amidase-containing microbial whole cell catalyst, under very mild conditions, a number of functionalized prochiral malonamides underwent enantioselective desymmetrization reaction to afford high yield of car
- Zhang, Li-Bin,Wang, De-Xian,Wang, Mei-Xiang
-
experimental part
p. 5604 - 5609
(2011/08/10)
-
- Asymmetric synthesis of α-methyl-α-amino acids via diastereoselective alkylation of (1s)-(+)-3-carene derived tricyclic iminolactone
-
A novel carene-based alanine-equivalent tricyclic iminolactone 16 has been synthesized via stereoselective dihydroxylation of the double bond, IBX oxidation of the secondary alcohol, esterification of the tertiary alcohol, deprotection of the resulting ester, and subsequent cyclization from commercially available (1S)-(+)-3-carene in 79% overall yield. The iminolactone 16 demonstrated high reactivity toward alkylation with a wide range of electrophiles at room temperature under phasetransfer catalysis conditions. The alkylated products were produced with excellent diastereoselectivities (>98% de) in good isolated yields (86-94%). High yields (83-91%) of optically pure (S)-R-methyl-R-substituted-R-amino acids were obtained by basic hydrolysis of the dialkylated iminolactones with the recovery of the chiral auxiliary 15 (78-87%).
- Lu, Ta-Jung,Lin, Cheng-Kun
-
experimental part
p. 1621 - 1633
(2011/06/17)
-
- Rapid asymmetric synthesis of amino acids via NiII complexes based on new fluorine containing chiral auxiliaries
-
New fluorine-containing chiral auxiliaries (S)-N-(2-benzoylphenyl)-1-(2- fluorobenzyl)-, (S)-N-(2-benzoylphenyl)-1-(3-fluorobenzyl)-, and (S)-N-(2-benzoylphenyl)-1-(4-fluorobenzyl)-pyrrolidine-2-carboxamide and their NiII complexes of Schiff bases with glycine and alanine have been synthesized. The greater efficiency of the complexes in terms of faster reaction rates and stereoselectivities in the asymmetric synthesis of (S)-α-amino acids has also been demonstrated.
- Saghyan, Ashot S.,Dadayan, Ani S.,Dadayan, Slavik A.,Mkrtchyan, Anna F.,Geolchanyan, Arpine V.,Manasyan, Luiza L.,Ajvazyan, Hrant R.,Khrustalev, Victor N.,Hambardzumyan, Hasmik H.,Maleev, Victor I.
-
experimental part
p. 2956 - 2965
(2011/03/19)
-
- Stereoselective functionalisation of cis- and trans-2-ferrocenyl-3- pivaloyl-4-alkyl-1,3-oxazolidin-5-ones: Asymmetric synthesis of (R)- and (S)-2-alkyl-2-aminopent-4-enoic acids and (2R,3S)-2-amino-2-methyl-3-hydroxy-3- phenylpropanoic acid
-
Treatment of a range of cis- and trans-2-ferrocenyl-3-pivaloyl-4-alkyl-1,3- oxazolidin-5-ones with LDA followed by the addition of allyl bromide promotes highly stereoselective allylation (>98% de) at the 4-position of the oxazolidinone ring anti to the s
- Alonso, Francisco,Davies, Stephen G.,Elend, Almut S.,Leech, Michael A.,Roberts, Paul M.,Smith, Andrew D.,Thomson, James E.
-
experimental part
p. 527 - 536
(2009/07/18)
-
- Asymmetric synthesis of α,α-disubstituted α-amino acids by diastereoselective alkylation of camphor-based tricyclic iminolactone
-
A novel and convenient route for the preparation of chiral tricyclic iminolactones 9 and 10 from camphorquinone has been developed. Alkylation of iminolactones 9 and 10 provided iminolactones 16 and 17 in high yields which were, in turn, alkylated again t
- Xu, Peng-Fei,Li, Shuo,Lu, Ta-Jung,Wu, Chen-Chang,Fan, Botao,Golfis, Georgia
-
p. 4364 - 4373
(2007/10/03)
-
- Halo-substituted (S)-N-(2-benzoylphenyl)-1-benzylpyrolidine-2-carboxamides as new chiral auxiliaries for the asymmetric synthesis of (S)-α-amino acids
-
The synthesis of new chiral auxiliaries (S)-N-(2-benzoylphenyl)-1-(3,4-dichlorobenzyl)-pyrrolidine-2-carboxamide (1a), (S)-N-(2-benzoylphenyl)-1-(pentafluorobenzyl)pyrrolidine-2-carboxamide (1b), and (S)-N-(2-benzoylphenyl)-1-(4-isopropoxytetrafluorobenzyl) pyrrolidine-2-carboxamide (1c) and their application in the asymmetric synthesis of amino acids using NiII complexes of their Schiff's bases with alanine and glycine are described. Compound la is particularly appropriate for highly stereoselective synthesis of α-methyl-α -amino acids with high enatiomeric purity (ee >95%).
- Belokon,Maleev,Petrosyan,Savel'eva,Ikonnikov,Peregudov,Khrustalev,Saghiyan
-
p. 1593 - 1599
(2007/10/03)
-
- The influence of imine structure, catalyst structure and reaction conditions on the enantioselectivity of the alkylation of alanine methyl ester imines catalyzed by Cu(ch-salen)
-
Systematic variation of the substrate structure has shown that the most effective substrates for Cu(ch-salen)-catalyzed asymmetric enolate alkylation reactions carried out under phase-transfer conditions are the para-chlorophenyl imines of amino esters. T
- Belokon', Yuri N.,Davies,Fuentes, Jose A.,North, Michael,Parsons, Teresa
-
p. 8093 - 8096
(2007/10/03)
-
- Chiral salen-metal complexes as novel catalysts for the asymmetric synthesis of α-amino acids under phase transfer catalysis conditions
-
Chiral salen-metal complexes have been tested as catalysts for the C-alkylation of Schiff's bases of alanine and glycine esters with alkyl bromides under phase-transfer conditions (solid sodium hydroxide, toluene, ambient temperature, 1-10 mol% of the catalyst). The best catalyst, which was derived from a Cu(II) complex of (1R, 2R or 1S,2S)-[N,N′-bis(2′-hydroxybenzylidene)]-1,2-diaminocyclohexane, gave α-amino and α-methyl-α-amino acids with enantiomeric excesses of 70-96%.
- Belokon, Yuri N,North, Michael,Churkina, Tatiana D,Ikonnikov, Nikolai S,Maleev, Victor I
-
p. 2491 - 2498
(2007/10/03)
-
- Asymmetric synthesis of α-Methyl α-Amino Acids through diastereoselective alkylation under mild reaction conditions of an iminic alanine template with a 1,2,3,6-Tetrahydro-2-Pyrazinone structure
-
(6R)-6-Isopropyl-3-methyl-5-phenyl-1,2,3,6-tetrahydro-2-pyrazinone, obtained from (R)-valine and (S)-alanine, is highly diastereoselectively alkylated at room temperature by: a) activated alkyl halides under solid-liquid PTC conditions, b) non-activated alkyl halides with organic bases, c) electrophilic olefins employing both solid-liquid PTC conditions and organic bases, and d) allylic carbonates by means of palladium catalysis under neutral conditions. Enantiomerically pure (S)-α-methyl α-amino acids 8 are obtained by hydrolysis of the alkylated pyrazinones.
- Najera, Carmen,Abellan, Tomas,Sansano, Jose M.
-
p. 2809 - 2820
(2007/10/03)
-
- Asymmetric PTC C-Alkylation Catalyzed by Chiral Derivatives of Tartaric Acid and Aminophenols. Synthesis of (R)- and (S)-α-Methyl Amino Acids
-
A new type of efficient chiral catalyst has been elaborated for asymmetric C-alkylation of CH acids under PTC conditions. Sodium alkoxides formed from chiral derivatives of tartaric acid and aminophenols (TADDOL's 2a-e and NOBIN's 3a-h) can be used as chiral catalysts in the enantioselective alkylation, as exemplified by the reaction of Schiffs bases la-e derived from alanine esters and benzaldehydes with active alkyl halides. Acid-catalyzed hydrolysis of the products formed in the reaction afforded (R)-α-methylphenylalanine, (R)-α-naphthylmethylalanine, and (R)-α-allylalanine in 61-93% yields and with ee 69-93%. The procedure could be successfully scaled up to 6 g of substrate 1b. When (S,S)-TADDOL or (R)-NOBIN are used, the (S)-amino acids are formed. A mechanism rationalizing the observed features of the reaction has been suggested.
- Belokon, Yuri N.,Kochetkov, Konstantin A.,Churkina, Tatiana D.,Ikonnikov, Nikolai S.,Chesnokov, Alexey A.,Larionov, Oleg V.,Singh, Ishwar,Parmar, Virinder S.,Vyskocil, Stepan,Kagan, Henri B.
-
p. 7041 - 7048
(2007/10/03)
-
- Mag: A Cα-methylated, side-chain unsaturated α-amino acid. Introduction into model peptides and conformational preference
-
By a chemo-enzymatic approach we synthesized the chiral, C(α)- methylated α-amino acid Mag, characterized by a side-chain C(γ)=C(δ) bond. We also prepared a series of model peptides containing Mag in combination with Aib and Ala. All of the peptides were fully characterized and their conformational preference was determined in solution by FT-IR absorption and 1H NMR investigations. X-Ray diffraction analyses of L-Mag, a derivative and three peptides are also presented. We find that this C(α)-methylated α- amino acid is an excellent β-turn and 310-helix former. A peptide with two Mag residues one on top of the other after one complete turn of the 310- helix has been synthesized and characterized. 2000 Elsevier Science Ltd.
- Peggion, Cristina,Flammengo, Roberto,Mossel, Eric,Broxterman, Quirinus B.,Kaptein, Bernard,Kamphuis, Johan,Formaggio, Fernando,Crisma, Marco,Toniolo, Claudio
-
p. 3589 - 3601
(2007/10/03)
-
- Enantioselective syntheses of 2-amino-4-fluoropent-4-enoic acids. Isosteres of asparagine
-
Diastereoselective alkylation of (R)-(+)-camphor-based glycine or alanine esterimines with 3-bromo-2-fluoropropene after hydrolytic deprotection gave (R)-(+)-2-amino-4-fluoropent-4-enoic acid with 38% overall yield and 90% ee, or (R)-(+)-2-amino-4-fluoro-2-methylpent-4-enoic acid (19% overall yield, 59% ee), respectively. Deprotection under drastic conditions was accompanied by hydrolysis of the fluorovinyl moiety to give (R)-(-)-2- amino-4-oxopentanoic acid hydrochloride with 28% overall yield and >95% ee. Ab initio calculations of acetamide and 2-fluoropropene as models for a primary amide or a fluorovinyl group despite of their different electronic structure show a similar electrostatic potential on the van der Waals surface suggesting their isosteric behavior.
- Laue, Klaus W.,Mueck-Lichtenfeld, Christian,Haufe, Guenter
-
p. 10413 - 10424
(2007/10/03)
-
- Asymmetric alkylation catalyzed by chiral alkali metal alkoxides of TADDOL. Synthesis of α-methyl amino acids
-
It is shown that sodium alkoxides formed from (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-bis(diphenylmethanol) ((R,R)-TADDOL) and some of its derivatives can be used as chiral catalysts for enantioselective alkylation of Schiff's bases derived from alanine with reactive alkyl halides. Acid hydrolysis of the reaction products affords (R)-α-methytphenyl-alanine, (R)-α-allylalanine, and (R)-α-methylnaphthylalanine in 61-93% yields and with ee 69-94%. When (S,S)-TADDOL is used, the (3)-amino acid is formed. A mechanism explaining the observed features of the reaction is proposed.
- Belokon',Kochetkov,Churkina,Ikonnikov,Chesnokov,Larionov,Kagan
-
p. 917 - 923
(2007/10/03)
-
- Chiral 3,6-dihydro-2H-1,4-oxazin-2-ones as alanine equivalents for the asymmetric synthesis of α-methyl α-amino acids (AMAAs) under mild reaction conditions
-
3,6-Dihydro-2H-1,4-oxazin-2-ones 1 act as very reactive chiral cyclic alanine equivalents and can be diastereoselectively alkylated or allylated using mild reaction conditions: potassium carbonate under phase-transfer catalysis (PTC) conditions when using activated alkyl halides, organic bases such as tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2- diazaphosphorine (BEMP) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) when using unactivated alkyl halides, and neutral Pd(0)-catalysis when allylic carbonates are used. In most cases, the diastereoselectivity under all these different reaction conditions is excellent although the reactions are always carried out at room temperature. Hydrolysis of the obtained alkylated or allylated oxazinones allows the preparation of enantiomerically enriched (S)- α-methyl α-amino acids (S)-AMAAs. The PTC and organic base methodologies have also been applied to the synthesis of (R)-α-methyl α-amino acids starting from (R)-alanine. When dihalides are used as electrophiles under PTC or BEMP conditions, a spontaneous N-alkylation also takes place giving bicyclic oxazinones, which can be hydrolyzed to enantiomerically pure cyclic (S)-AMAAs.
- Chinchilla, Rafael,Galindo, Nuria,Nájera, Carmen
-
p. 704 - 717
(2007/10/03)
-
- Asymmetric synthesis of α-methyl α-amino acids by diastereoselective alkylation of optically active 6-isopropyl-3-methyl-2,3-dihydro-6H-1,4-oxazin-2-ones
-
At room temperature already highly diastereoselective alkylation of the new, cyclic, chiral alanine ester derivatives (6R)-1 can be achieved with either K2CO3 as base under solid liquid phase-transfer catalysis or Pd catalysis under neutral conditions. The products (3S,6R)-2 can be easily hydrolyzed to form (S)-α-methyl α-amino acids.
- Chinchilla,Falvello,Galindo,Najera
-
p. 995 - 997
(2007/10/03)
-
- Synthesis of Modified Partial Structures of the Bacterial Cell Wall. 2. Retarded Metabolism of Lipopeptides by Insertion of α-Substituted α-Amino Acids
-
The synthesis of the lipopeptide 1, which exhibits both immunological activity (induction of the colony stimulating factor (CSF) and stability against metabolic degradation, has been described.A detailed investigation of the course of the ene reaction bet
- Frauer, Alexandra,Mehlfuehrer, Michaela,Thirring, Klaus,Berner, Heinz
-
p. 4215 - 4222
(2007/10/02)
-
- Enzymatic resolution of α,α-disubstituted α-amino acid esters and amides
-
The scope and limitations of the enzymatic resolution of α,α-disubstituted α-amino acid amides by an amino acid amidase from Mycobacterium neoaurum and of the corresponding ethyl esters with Pig liver esterase (PLE) have been studied. Moderate enantiomeric excesses were obtained with PLE, with only a narrow substrate specificity. Mycobacterium neoaurum on the contrary yields a broad range of S-α,α-disubstituted α-amino acids 1 and the corresponding R-amides 2.
- Kaptein,Boesten,Broxterman,Peters,Schoemaker,Kamphuis
-
p. 1113 - 1116
(2007/10/02)
-
- Synthesis of (Optically Active) Sulfur-Containing Trifunctional Amino Acids by Radical Addition to (Optically Active) Unsaturated Amino Acids
-
Sulfur-based radicals, generated from R-S-H-type precursors (R = alkyl, acyl) with AIBN, smoothly add to α-allylglycines protected at none, one, or both of the amino acid functions (NH2 and/or CO2H).Sulfur-containing trifunctional amino acids were obtained in good to excellent yields (64-100 percent).The solvent used for the reaction is critical.Optimal results were obtained when both the unsaturated amino acid and RSH dissolve completely in the medium (dioxane/water or methanol/water are good solvent systems).The scope of the reaction includes α-substituted α-allylglycine derivative and derivatives as well as β-substituted β-allyl-β-amino alcohols.In the case of optically active α-allylglycine derivatives, radical addition is accompanied by a small amount of racemization, the amount depending on the type of protection and R-S-H.The products are easily optically enriched by crystallization.Addition of sulfur-based radicals to α-allylglycine is believed to be an example of a general method for synthesizing optically active trifunctional amino acids from unsaturated amino acids.
- Broxterman, Quirinus B.,Kaptein, Bernard,Kamphuis, Johan,Schoemaker, Hans E.
-
p. 6286 - 6294
(2007/10/02)
-
- GENERAL METHOD FOR THE ASYMMETRIC SYNTHESIS OF α-AMINO ACIDS VIA ALKYLATION OF THE CHIRAL NICKEL(II) SCHIFF BASE COMPLEXES OF GLYCINE AND ALANINE
-
Nickel(II) complexes of Schiff bases derived from (S)-o-benzaldehyde and alanine (3), or (S)-O-benzophenone and alanine (4), or glycine (5) have been used for the asymmetric synthesis of α-amino acids under a variety of conditions.The method of choice consists of the reaction of the corresponding complex with the appropriate alkyl halide in DMF at 25 deg C using solid NaOH as a catalyst.Low diastereoselective excess (d.e.) is observed for the alkylation of complex (3) with benzyl bromide and allyl bromide.Large selectivity (80 percent) is observed for the alkylation of complex (4).Optically pure(R)- and (S)-O-benzyl-α-methyl-α-amino acids were obtained (70-90 percent) after the alkylated diastereoisomeric complexes had been seperated on SiO2 and hydrolysed with aqueous HCl.The initial chiral reagents were recovered (80-92 percent).The alkylation of complex (5) gave (S)-alanine, (S)-valine, (S)-phenylalanine, (S)-tryptophan, (S)-isoleucine, (S)-2-aminohexanoic acid, and 3,4-dimethoxyphenylalanine with optical yields of 70-92 percent.The optically pure α-amino acids were obtained after the separation of the alkylated diastereoisomeric complexes on SiO2.The stereochemical mechanism of the alkylation reaction is discussed.
- Belokon, Yuri N.,Bakhmutov, Vladimir I.,Chernoglazova, Nina I.,Kochetkov, Konstantin A.,Vitt, Sergei V.,et al.
-
p. 305 - 312
(2007/10/02)
-
- Preparation of Optically Pure α-Methyl-α-amino Acids via Alkylation of the Nickel(II) Schiff Base of (R,S)-Alanine with (S)-2-N-(N'-Benzylprolyl)aminobenzaldehyde
-
Chiral nickel(II) complexes of Ala with (S)-2-N-(N'-benzylprolyl)aminobenzaldehyde were alkylated with alkyl halides and the diastereoisomeric complexes formed were separated on SiO2; their decomposition led to the isolation of enantiomerically pure (R)- and (S)-α-alkyl-α-amino acids with recovery of the initial (S)-bba.
- Belokon', Yuri N.,Chernoglazova, Nina I.,Kochetkov, Constantin A.,Garbalinskaya, Natalia S.,Belikov, Vasili M.
-
p. 171 - 172
(2007/10/02)
-