- SYNTHESIS OF HYPERBRANCHED POLYMETHACRYLATES AND POLYACRYLATES BY A HALOINIMER APPROACH
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A new synthetic pathway for hyperbranched polyacrylates and polymethacrylates including the steps of preparing an inimer and polymerizing the inimer to form hyperbranched polymers or copolymers.
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Paragraph 0049-0050
(2020/03/01)
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- Method for preparing 2-methylserine
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The invention relates to a method for preparing 2-methylserine, and mainly solves the technical problem of being long in route, complicated in operation, and not conducive to mass production of the existing synthetic method. The method comprises the following steps: Cbz-chiral alanine and Benzaldehyde dimethyl acetal are reacted under the action of thionyl chloride and zinc chloride, a reaction product is crystallized to obtain an intermediate 1, the intermediate 1 is reacted under cooperation of an alkaline reagent to obtain an intermediate 2, an intermediate 3 is obtained from the intermediate 2 by the action of lithium hydroxide, and the final product 2-methylserine is obtained from the intermediate 3 by palladium carbon catalytic hydrogenolysis. High purity 2-methylserine can be obtained by the method.
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Paragraph 0036; 0039
(2019/01/24)
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- SELENOCYSTINE DERIVATIVES, ALPHA-METHYLSELENOCYSTEINE, ALPHA-METHYLSELENOCYSTEINE DERIVATIVES, AND METHODS OF MAKING AND USING SAME
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Provided are selenocysteine derivatives (e.g., deuterium and tritium analogs), α-methylselenocysteine, and α-methylselenocysteine derivatives. These compounds can be incorporated in more complex chemical structures (e.g., polymers, proteins, peptides, and
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Paragraph 0085
(2016/08/29)
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- A concise synthesis of (+)-conagenin and its isomer using chiral tricyclic iminolactones
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An efficient synthesis of (+)-conagenin, a novel immunomodulator produced by Streptomyces roseosporus, has been achieved via the shortest route at present. At the same time, 2-epiconagenin was synthesized according to the same methodology.
- Wang, Hai-Fei,Ma, Guo-Hua,Yang, Shao-Bo,Han, Rong-Gang,Xu, Peng-Fei
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p. 1630 - 1635
(2008/12/21)
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- Cloning of the gene encoding α-methylserine hydroxymethyltransferase from Aminobacter sp. AJ110403 and Ensifer sp. AJ110404 and characterization of the recombinant enzyme
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Genes encoding α-methylserine hydroxymethyltransferase from Aminobacter sp. AJ110403 and Ensifer sp. AJ110404 were cloned and expressed in Escherichia coli. The purified enzymes were homodimers with a 46-kDa subunit and contained 1 mol/mol-subunit of pyridoxal 5′-phosphate. The V max of these enzymes catalyzing the conversion of α-methyl-L-serine to D-alanine via tetrahydrofolate was 22.1 U/mg (AJ110403) and 15.4 U/mg (AJ110404).
- Nozaki, Hiroyuki,Kuroda, Shinji,Watanabe, Kunihiko,Yokozeki, Kenzo
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body text
p. 3002 - 3005
(2009/04/07)
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- Theoretical evidence for pyramidalized bicyclic serine enolates in highly diastereoselective alkylations
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A new chiral serine equivalent and its enantiomer have been synthesized from (S)- and (R)-N-Bocserine methyl esters (Boc: tert-butyloxy-carbonyl). The use of these compounds as chiral building blocks has been demonstrated in the synthesis of α-alkyl α-amino acids by diastereoselective po tassium enolate alkylation reactions and subsequent acid hydrolyses. Theoretical studies were performed to eluci date the stereochemical outcome of both the formation of five-membered cyclic N,O-acetals and the subsequent alkylation process, which occurs with total retention of configuration. This feature could be explained in terms of the high degree of pyramidalization of enolate intermediates.
- Aydillo, Carlos,Jimenez-Oses, Gonzalo,Busto, Jesus H.,Peregrina, Jesus M.,Zurbano, Maria M.,Avenoza, Alberto
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p. 4840 - 4848
(2008/02/04)
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- Stereoselective addition of organometallic reagents to a chiral acyclic nitrone derived from L-erythrulose
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The additions of various organolithium and organomagnesium reagents to a chiral nitrone prepared from L-erythrulose took place with variable diastereoselectivity. The degree and strength of the facial selectivity can be modified if the reaction is performed in the presence of Lewis acid additives: zinc bromide enhances the attack to the Si face of the C=N bond whereas diethyl aluminium chloride promotes attack to the Re face. The obtained adducts can be then transformed into protected N-hydroxy-α,α-disubstituted-α- amino acid derivatives as well as into the corresponding α,α- disubstituted α-amino acids.
- Murga, Juan,Portoles, Raul,Falomir, Eva,Carda, Miguel,Marco, J. Alberto
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p. 1807 - 1816
(2007/10/03)
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- Enantioselective synthesis of α-methyl-D-cysteine and lanthionine building blocks via α-methyl-d-serine-β-lactone
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(Matrix presented) We report here the enantioselective synthesis of Boc-α-methyl-D-cysteine(PMB)-OH and lanthionine building blocks through the regioselective ring opening of key intermediate Boc-α -methyl-D-serine-β-lactone.
- Smith, Nicole D.,Goodman, Murray
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p. 1035 - 1037
(2007/10/03)
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- Synthesis of α,α-disubstituted α-amino acid derivatives in enantiopure form via stereoselective addition of Grignard reagents to a chiral acyclic nitrone derived from L-erythrulose
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The additions of various Grignard reagents to a chiral nitrone prepared from L-erythrulose take place with variable diastereoselectivity. The degree and strength of the facial selectivity can be modified if the reaction is performed in the presence of Lewis acidic additives: zinc bromide enhances attack to the si face whereas diethyl aluminum chloride promotes attack to the re side. The obtained adducts can be then efficiently transformed into protected N-hydroxy α,α-disubstituted α-amino acid derivatives as well as into the corresponding α,α-disubstituted α-amino acids.
- Portole?s, Raul,Murga, Juan,Falomir, Eva,Carda, Miguel,Uriel, Santiago,Marco, J. Alberto
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p. 711 - 714
(2007/10/03)
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- Asymmetric synthesis of (S)-and (R)-α-methylserine based on the chiral recyclable reagent (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide
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Both enantiomers of α-methylserine were synthesized with the use of NiII complexes based on the chiral recyclable reagent (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide. Intermediate diastereomeric complexes were separated by crystal
- Belokon',Maleev,Savel'eva,Ikonnikov
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p. 1037 - 1040
(2007/10/03)
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- Novel and efficient transformation of α-amino nitrile to α-imino and α-amide nitriles in asymmetric Strecker synthesis
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Oxidation of α-amino nitrile 4 with ozone gave rise to a mixture of α-imino nitrile 5 and a novel fragmentation product of 6 in one-step. The mixture was converted to a variety of α-substituted α-amino acids 7 in high yields, which enabled the asymmetric transferring Strecker synthesis to be a widely useful method.
- Namba, Kosuke,Kawasaki, Masanori,Takada, Ichinori,Iwama, Seiji,Izumida, Masashi,Shinada, Tetsuro,Ohfune, Yasufumi
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p. 3733 - 3736
(2007/10/03)
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- Enantioselective synthesis of (S)- and (R)-α-methylserines: Application to the synthesis of (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinals
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This report describes the synthesis of enantiomerically pure (S)- and (R)-α-methylserines on a multigram scale, starting from the Weinreb amide of 2-methyl-2-propenoic acid and using a stereodivergent synthetic route that involves a Sharpless asymmetric dihydroxylation reaction. As a synthetic application of these quaternary α-amino acids, they were used as starting materials in the synthesis of the well-known valuable homochiral (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinal building blocks.
- Avenoza, Alberto,Cativiela, Carlos,Corzana, Francisco,Peregrina, Jesus M.,Sucunza, David,Zurbano, Maria M.
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p. 949 - 957
(2007/10/03)
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- 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
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(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.
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p. 2809 - 2820
(2007/10/03)
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- Synthesis of (S)-N-tert-butoxycarbonyl-N,O-isopropylidene-α- methylserinal: A potential building block for the asymmetric synthesis of non-natural amino acids
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The title compound (S)-α-methylserinal acetonide has been efficiently prepared from (S)-α-methylserine, which is readily available in enantiomerically pure form by Curtius rearrangement of α,α-dialkyl 2- cyanoesters obtained by diastereoselective alkylation of (1S,2R,4R)-10- dicyclohexylsulfamoylisobornyl 2-cyanopropanoate using methoxymethyl iodide or paraformaldehyde as electrophiles by an extension of our recently developed methodology for the synthesis of α,α-dialkylamino acids.
- Alias, Myriam,Cativiela, Carlos,Diaz-De-Villegas, Maria D.,Galvez, Jose A.,Lapena, Yolanda
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p. 14963 - 14974
(2007/10/03)
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- Stereoselective synthesis of α-substituted serines from protected erythrulose oximes
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The additions of organolithium reagents to the C=N bond of several chiral oxime ethers derived from erythrulose afforded protected amino polyols with high diastereoselectivity. Four of the latter compounds have been convened into the α,α-disubstituted α-amino acids (R)-2-(-)-methylserine, (S)-2-(+)-methylserine, (R)-(+)-2-phenylserine and (R)-(-)-2-n-butylserine.
- Carda,Murga,Rodriguez,Gonzalez,Castillo,Marco
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p. 1703 - 1712
(2007/10/03)
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- Diastereoselective additions of organolithium reagents to the C=N bond of protected erythrulose oxime ethers. Synthesis of enantiopure α,α-disubstituted α-aminoacids
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The addition of organolithium reagents to the C=N bond of several erythrulose-derived chiral (E)- and (Z)-ketoxime ethers has been shown to be highly diastereoselective for the (E)-isomers. A chelated transition state has been proposed to explain this result. The addition products were converted into the two α,α-disubstituted α-aminoacids (R)-2-(-)-methylserine and (R)-(+)-2-phenylserine.
- Marco, J. Alberto,Carda, Miguel,Murga, Juan,Gonzalez, Florenci,Falomir, Eva
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p. 1841 - 1844
(2007/10/03)
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- A new synthesis of α-methylserine by nucleophilic ring-opening of N-sulfonyl aziridines
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Conversion of tritylated 2-methylglycidol to the corresponding aziridine occurs by Staudinger cyclization of the intermediate azido alcohol. After N-sulfonylation with Ses-Cl and ring-opening with benzyl alcohol, oxidation of the primary alcohol provides. N,O-bisprotected α-methylserine directly suitable for repetitive peptide synthesis. This sequence represents a general enantioselective protocol for the synthesis of α-methylserine and other α,α-disubstituted amino acids.
- Wipf, Peter,Venkatraman, Srikanth,Miller, Chris P.
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p. 3639 - 3642
(2007/10/02)
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- Asymmetric Synthesis of α-Alkyl-α-amino Acids from Chromium-Carbene-Complex-Derived β-Lactams
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Optically active bicyclic β-lactam 3 was synthesized by photolysis of optically active oxazolidine carbene chromium complex 1 with oxazine 2.Conversion of the oxazolidine to the oxazolidinone gave a bicyclic β-lactam readily α-alkylated.Cleavage of the alkylated β-lactam gave optically active ester aldehyde 7, which was converted to a number of optically active α-alkyl-α-amino acids.These include (R)-α-methylserine, (S)-α-methylglutamic acid, (S)-α-methylornithine, (S)-vinylalanine, (S)-ethynylalanine, and (S)-2-methyl-2,3-diaminopropionic acid.
- Colson, Pierre-Jean,Hegedus, Louis S.
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p. 5918 - 5924
(2007/10/02)
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- PREPARATIVE ASYMMETRIC SYNTHESIS OF (R)- AND (S)-α-METHYLSERINE Ni(II) COMPLEX WITH A SCHIFF BASE OF α-ALANINE AND (S)-2-BENZOPHENONE
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The kinetic and thermodynamic diastereoselectivity of the hydroxymethylation of the alanine fragment in the Ni(II) complex of the Schiff base of alanine and (S)-2-benzophenone (BBP) was studied.Optically pure (R)- and (S)-α-methylserines were synthesized.
- Belokon', Yu. N.,Tararov, V. I.,Savel'eva, T. F.
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p. 1054 - 1058
(2007/10/02)
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- Functionalized Amino Acid Complexation to a Cobalt(III) Complex of (2R,5R,8R,11R)-2,5,8,11-Tetraethyl-1,4,7,10-tetra-azacyclododecane. Crystal Structures of Complexes containing (R)- or (S)-Serine and (R)-α-Methylserine, and Release of Amino Acid from the Complexes
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The complex Br2 (1) reacts with a racemic neutral amino acid having a hydroxymethyl group to give a pair of diastereomeric complexes.One of these crystallized preferentially as its appropriate salt.The less-soluble complex co-ordinated its (R)-amino acid.Structure determinations of (R)- or (S)-serinato (serO) and (R)-α-methylserinato (mseO) complexes, (3)-(5), showed that each hydroxyl group in the amino acid forms a hydrogen bond.The OH group of (R)-amino acids takes part in an intramolecular hydrogen bond to one of the secondary nitrogen atoms in L, and that of (S)-serO in (4) interacts with a cocrystallized water molecule and with an anion.Such different hydrogen-bonding formation results in different solubility between the diastereomers, and allows them to be isolated.Only a powdery solid was obtained for the complex co-ordinating (S)-mseO.Slightly racemized (R)- and (S)-ser and optically pure mse were obtained upon release from the corresponding complexes.Further, complex (1) was regenerated in good yield.The resolution expressed as the different solubilities between two salts in this series is ascribed to the effect of a three-point attachment.
- Tsuboyama, Sei,Miki, Shigeru,Chijimatsu, Tamiko,Tsuboyama, Kaoru,Sakurai, Tosio
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p. 2359 - 2366
(2007/10/02)
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- Kinetic Resolution of Unnatural and Rarely Occuring Amino Acids: Enantioselective Hydrolysis of N-Acyl Amino Acids Catalyzed by Acylase I
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Acylase I (aminoacylase; N-acylamino-acid amidohydrolase, EC 3.5.1.14, from porcine kidney and the fungus Aspergillus) is broadly applicable enzymatic catalyst for the kinetic resolution of unnatural and rarely occuring α-amino acids.Its enantioselectivity for the hydrolysis of N-acyl L-α-amino acids is nearly absolute, yet it accepts substrates having a wide range of structure and functionality.This paper reports the initial rates of enzyme-catalyzed hydrolysis of over 50 N-acyl amino acids and analogues, the stabilities of the enzymes in aqueous and aqueous/organic solutions, and the effects of different acyl groups and metal ions on the rates of enzymatic hydrolysis.Eleven α-amino and α-methyl α-amino acids were resolved on a 2-29-g scale.Crude L- and D-amino acid products had generally >90percent ee.The utility of resolved amino acids as chiral synthons was illustrated by the preparation of (R)- and (S)-1-butene oxide and the diastereoselective (cis:trans, 7-8:1) iodolactonization of three 2-amino-4-alkenoic acid derivatives.
- Chenault, H. Keith,Dahmer, Juergen,Whitesides, George M.
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p. 6354 - 6364
(2007/10/02)
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- ASYMMETRIC ALDOL REACTION OF α-ISOCYANOCARBOXYLATES WITH PARAFORMALDEHYDE CATALYZED BY CHIRAL FERROCENYLPHOSPHINE-GOLD(I) COMPLEXES: CATALYTIC ASYMMETRIC SYNTHESIS OF α-ALKYLSERINES
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Aldol reaction of methyl α-isocyanocarboxylates (CNCH(R)COOMe: R=H, Me, Et, i-Pr, Ph) with paraformaldehyde in the presence of 1 molpercent of a chiral (aminoalkyl)ferrocenylphosphine-gold(I) complex gave optically active 4-alkyl-2-oxazoline-4-carboxylates (up to 83percent ee) which were readily hydrolyzed to α-alkylserines.
- Ito, Yoshihiko,Sawamura, Masaya,Shirakawa, Eiji,Hayashizaki, Keiichi,Hayashi, Tamio
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p. 235 - 238
(2007/10/02)
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- SOLID-LIQUID PHASE TRANSFER CATALYTIC SYNTHESIS OF α-AMINO ACID VIA ALKYLATION AND NUCLEOPHILIC ADDITION OF BENZALDEHYDE IMINES
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A short, mild and efficient synthetic route of α-amino acid via alkylation, Michael addition and carbonyl addition as well as cycloaddition of aldimines derived from glycine and alanine esters with benzaldehyde under solid-liquid phase transfer catalytic condition has been studied.The key to solid-liquid phase transfer catalyzed reactions is the selection of a base for the various reactants.The yield is dependent on the base used.The results obtained using KOH, K2CO3 and Na2CO3 are discussed.The kinetics of solid-liquid PTC benzylation has been investigated and we propose a possible mechanism of solid-liquid PTC as an interface auto-catalytic procedure.The details of some syntheses of α-amino acids are presented.
- Yaozhong, Jiang,Changyou, Zhou,Shengde, Wu,Daimo, Chen,Youan, Ma,Guilan, Liu
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p. 5343 - 5354
(2007/10/02)
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- Enzyme-Catalysed Hydrolysis of Some Functionalized Dimethyl Malonates
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A method is described for the preparation of (+)-(R)-methyl hydrogen 2-(tert-butoxymethyl)-2-methylmalonate (5e) in synthetically useful amounts from readily available starting material.
- Luyten, Marcel,Mueller, Susanna,Herzog, Beat,Keese, Reinhart
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p. 1250 - 1254
(2007/10/02)
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- Stereoselective Alkylierung an C(α) von Serin, Gycerinsaeure, Thereonin und Weinsaeure ueber heterocyclische Enolate mit exocyclischer Doppelbindung
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The chiral, non-racemic title acids are converted to methyl dioxalene- (cf. 13), oxazoline- (4) and oxazolidine-carboxylates (cf. 9).Deprotonation by Li(i-Pr)2N at dry-ice temperature gives solutions of the litium enolates A-D with exocyclic enolate double bonds.These are stable enough with respect to β-elimination (Scheme 1) to be alkylated with or without cosolvents such as HMPA or DMPU.The products are formed in good to excellent yields and, with the exception of the tartrate derived acetonide (see Schemem 2), with diastereoselectivities above 90percent.While the tartrate- and threonine-derived enolates (A and B, resp.) are chiral due to the second stereogenic center of the precursors, the serine- and glyceric-acid-derived enolates are non-racemic due to a tert butyl-substituted (pivalaldehyde-derived) acetal center (C and D, resp.).The products of alkylation can be hydrolyzed to give α-branched tartaric acid (Scheme 2), allothreonine (Scheme 3), serine (Scheme 4), and glycerine-acid derivatives (Scheme 5) with quaternary stereogenic centers.The configurations of the products are determined by NOE-NMR measurements and by chemical correlation.These show taht the dioxolane-derived enolates A and D are alkylated preferentially from that face of the ring which is alredy substituted ('syn'-attack).The 'syn'-attack is postulated to arise from strong folding of the heterocyclic ring due to elelctronic repulsion between the enolate ?-system and non-bonding elelctron pairs on the heteroatoms (see Scheme 6).
- Seebach, Dieter,Aebi, Johannes D.,Gander-Coquoz, Marlyse,Naef, Reto
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p. 1194 - 1216
(2007/10/02)
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- α-ALKYLATION OF SERINE WITH SELF-PRODUKTION OF THE CENTER OF CHIRALITY
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The lithium enolate 6 of methyl (2R,4S)-2-t-butyl-3-formyl-oxazolidine-4-carboxylate (4b) derived from (S)-(+)-serine can be generated with LDA in THF solution at -75 deg C.Alkylations (9) and hydroxyalkylations (10,11) occur preferentially (>95:5) from the Re-face of the donor center (relative topicity lk).This stereochemical course is derived from the absolute configuration of 2-deuterio- and 2-methyl-serine (12,13) obtained through the enolate 6.
- Seebach, Dieter,Aebi, Johannes D.
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p. 2545 - 2548
(2007/10/02)
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- ENANTIOSELECTIVE SYNTHESIS OF NON-PROTEINOGENIC AMINO ACIDS VIA METALLATED BIS-LACTIM ETHERS OF 2,5-DIKETOPIPERAZINES
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Bis-lactim ethers 1 of 2,5-diketopiperazines contain a chiral inducing center, an acidic CH-bond and two sites susceptible to hydrolysis.They react with BuLi to give Li compounds of type 4, 15, 29 or 32, which possess a prochiral C atom.They readily add electrophiles (such as alkylating agents or carbonyl compounds) with unusually high diastereoface differentiation.In many cases the d.e-value (d.e. = diastereomeric excess = asymmetric induction) of the adduct exceeds 95percent.On hydrolysis the adducts are cleaved liberating the chiral auxiliary (used to build up the bis-lactim ether 1) and the target molecules, the optically active amino acid methyl esters of type 8, 19, 25 or 36.The two amino acid esters are separable either by fractional distillation or (eventually after further hydrolysis to amino acids) by chromatography.Transition state models are discussed that could explain the exceptionally high asymmetric induction and the predictability of the induced configuration.
- Schoellkopf, Ulrich
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p. 2085 - 2092
(2007/10/02)
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- Asymmetric Syntheses via Heterocyclic Intermediates, XI Enantioselective Synthesis of (R)-(-)-α-Methylserine
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Die Titelverbindung 7 wurde in enantiomerenreiner Form durch asymmetrische Synthese dargestellt unter Verwendung des Bislyctimethers 1 von cyclo-(L-Val-DL-Ala) als Ausgangsverbindung.
- Groth, Ulrich,Chiang, Yao-chung,Schoellkopf, Ulrich
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p. 1756 - 1757
(2007/10/02)
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- Asymmetric Syntheses via Heterocyclic Intermediates, X. - Enantioselective Synthesis of (2R)-2-Methylserines
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Aldehydes and ketones react with the lithiated bislactim ether 3 of cyclo-(L-Ala-L-Ala) with 81 to >95percent asymmetric induction (d.e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly. - A model concept for the asymmetric induction is proposed. - With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here with d. e. 47 - 73percent.Hydrolysis of the addition products 6 (0.25 N HCl, room temperature) gives L-Ala-OCH3 and (2R)-2-methylserine methyl esters 7.Both compounds can be separated either at the ester stage by distillation or - if 7 is thermolabile - after further hydrolysis at the amino acid stage.
- Schoellkopf, Ulrich,Groth, Ulrich,Hartwig, Wolfgang
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p. 2407 - 2418
(2007/10/02)
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