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Asymmetric Synthesis (asymmetric + synthesis)
Kinds of Asymmetric Synthesis Selected AbstractsEnantioselective Butenolide Preparation for Straightforward Asymmetric Syntheses of ,-Lactones , Paraconic Acids, Avenaciolide, and Hydroxylated EleutherolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2006Stefan Braukmüller Abstract The naturally occurring ,-lactones (+)-methylenolactocin (13) and its enantiomer, (+)-protolichesterinic acid (14) and its enantiomer, (+)-rocellaric acid (15), and the methylene bis(,-lactone) (,)-avenaciolide (16) were synthesized with 95,98,% ees in very few steps. Enantiocontrol was imposed by the asymmetric dihydroxylation of trans -configured ,,,-unsaturated carboxylic esters (namely compounds 1i, 1j, and 1n) with AD mix-,® [for the levorotatory target structures, except for (,)-avenaciolide] or AD mix-,® [for the dextrorotatory target structures plus (,)-avenaciolide]. ,,,-Unsaturated carboxylic ester 1e required increased amounts of the oxidant and auxiliary to produce the hydroxy lactone R,R - 3e, a precursor of the naphtho-,-lactone (+)-9-hydroxyeleutherol (12; 96,% ee). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Diacetone-D-glucose-Mediated Asymmetric Syntheses of N-Carboxyalkylated and O-Carboxyalkylated Flavones.CHEMINFORM, Issue 50 2007Kyoung Hee Kang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A General Approach to (5S,6R)-6-Alkyl-5-benzyloxy-2-piperidinones: Application to the Asymmetric Syntheses of Neurokinin Substance P Receptor Antagonist (-)-L-733,061 and (-)-Deoxocassine.CHEMINFORM, Issue 1 2005Liang-Xian Liu Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Catalytic Asymmetric Syntheses of ICI-199441 and CP-99994 Using Nitro-Mannich Reaction.CHEMINFORM, Issue 33 2002Natsuko Tsuritani Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Asymmetric Syntheses of Fused Bicyclic Compounds by Conjugate Additions of Allylic Organolithium Species to Activated Olefins and Subsequent Cyclizations.CHEMINFORM, Issue 28 2001Sung H. Lim Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Asymmetric Syntheses Aided by BiocatalystsCHINESE JOURNAL OF CHEMISTRY, Issue 8 2003Pei-Ran This article summarizes the achievements of the authors' group in the area of biocatalyst-catalyzed organic reactions in recent 10 years. A strain of Geotrichum sp. obtained by screening is capable of stereoselectively reducing a number of carbonyl compounds. In many cases, the stereochemistry is complementary with that obtained by baker' s yeast. Therefore, this microorganism provides a useful pathway to the preparation of alcohol compounds with specific configurations. On the other hand, a number of plant sources have been screened for oxynitrilases and the hydrocyanation reactions of various arylcarboxaldehydes have been investigated. A "micro-aqueous reaction system" was invented, by which a series of novel optically active cyanohydrins were prepared. On this basis, a high through-put continuous reaction system has been designed. This paper also describes examples of the syntheses of bio-active compounds by using the optically active compounds obtained from the above-mentioned catalytic reactions as precursors. [source] Comparative Study of Cyanobacteria as Biocatalysts for the Asymmetric Synthesis of Chiral Building BlocksENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2006J. Havel Abstract The three representative cyanobacteria, Synechococcus PCC7942, Anabaena variabilis, and Nostoc muscorum, were studied for their ability to asymmetrically reduce the prochiral ketones 2,-3,-4,-5,-6,-pentafluoroacetophenone, ethyl 4-chloroacetate, 4-chloroacetophenone, and ethylbenzoylacetate to the corresponding chiral alcohols. Photosynthesis as well as respiration was applied for intracellular regeneration of the NAD(P)H cofactor. It was shown for the first time that all cyanobacteria were able to reduce the prochiral ketones asymmetrically without light for cofactor regeneration. By comparison of the cell specific product formation capacities of cyanobacteria with typical heterotrophic whole cell biocatalysts in batch processes, it is shown that comparable or, in some cases, better performances at high enantiomeric excess (ee > 99.8,%) are obtained. As a consequence of a generally strong product inhibition, in situ product removal must be applied in order to restore process efficiency when using cyanobacteria as biocatalysts. [source] Metal Effects on the Asymmetric Synthesis of a New Heterobidentate As/P=S LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2010Mengtao Ma Abstract The cycloaddition reaction between 3,4-dimethyl-1-phenylarsole and diphenylvinylphosphane sulfide was promoted by chiral palladium and platinum complexes containingortho -metalated (S)-[1-(dimethylamino)ethyl]naphthalene. They exhibited similar stereoselectivity; the palladium cycloadducts could not be separated via column chromatography and fractional crystallization, however, the corresponding platinum complexes could be successfully converted into their enantiomerically pure counterpart. A formal arsanylidene elimination reaction was observed on the liberated free As/P=S bidentate ligand. [source] Asymmetric Synthesis of (1,3-Butadien-2-yl)methanols from Aldehydes via [1-(Silylmethyl)allenyl]methanolsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2010María Durán-Galván Abstract [1-(Silylmethyl)allenyl]methanols 2 were efficiently synthesized from aldehydes and (4-bromobut-2-ynyl)trimethylsilane in the presence of a catalytic amount of CrCl2 and tridentate carbazole ligands. The desired compounds were obtained with good yields (43,88,%) and enantioselectivities (55,78,% ee). Alcohols 2 may be treated with TBAF or 2 M HCl in the case of aliphatic substrates, to provide (1,3-butadien-2-yl)methanols 3 in 43,81,% yields. This method allows the synthesis of dienes 3 with no regioselectivity problems, and it tolerates a large number of functionalities. [source] Asymmetric Synthesis of ES-285, an Anticancer Agent Isolated from Marine SourcesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 35 2009Ana C. Allepuz Abstract The asymmetric synthesis of (2S,3R)-2-amino-3-octanedecanol hydrochloride (ES-285·HCl) was achieved in eight steps in ca. 38,% overall yield from the N -benzylimine-derived from (R)-2,3- O -isopropylidene glyceraldehyde, which is easily available on gram scale from the inexpensive precursor D -mannitol. Highly diastereoselective addition of methylmagnesium bromide to the N -benzylimine was the key step to create the vic -amino alcohol moiety with the appropriate configuration. Regioselective ring opening of an intermediate aminoepoxide enabled the introduction of the long hydrocarbon chain at C4.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Enantiocomplementary Chemoenzymatic Asymmetric Synthesis of (R)- and (S)-ChromanemethanolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2009Michael Fuchs Abstract A non-lipase-based, enantiocomplementary chemoenzymatic route towards enantiopure (R)- and (S)-chromanemethanol (12), which are the key building blocks for the synthesis of stereoisomerically pure ,-tocopherols, has been achieved by the biocatalytic resolution of a racemic 2,2-disubstituted oxirane using an epoxide hydrolase and a halohydrin dehalogenase, which exhibit opposite enantiopreferences. The introduction of chirality at an early stage of the synthesis ensured a high efficiency, leading to total overall yields of 16 and 26,% for (R)- and (S)-chromanemethanol (12), respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Asymmetric Synthesis of a Novel Conformationally Constrained D -Lysine Analogue with a Piperidine SkeletonEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2008Pablo Etayo Abstract A practical asymmetric synthesis of enantiomerically pure(2R,4R)-1-(tert -butoxycarbonyl)-4-[2-(methoxycarbonylamino)ethyl]pipecolic acid starting from easily accessible (R)-2-[(S)-1,2-bis(benzyloxy)ethyl]-1-[(S)-1-phenylethyl]-4-piperidone in around 33,% overall yield has been performed. The efficiency of the synthetic strategy developed for the synthesis of this novel conformationally constrained D -lysine analogue relies on the high-yielding Wadsworth,Emmons reaction of a 2-substituted 4-piperidone and the diastereoselective reduction of the exocyclic C=C double bond at the 4-position of the piperidine ring.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Asymmetric Synthesis of (S)-Mirtazapine: Unexpected Racemization through an Aromatic ipso -Attack MechanismEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2008Marco van der Linden Abstract An asymmetric synthesis of (S)-mirtazapine has been achieved from the synthesis of the racemate by using (S)-1-methyl-3-phenylpiperazine as the starting material. Unfortunately, significant racemization was encountered in the final step, which involved an electrophilic aromatic ring closure of a alcohol by concentrated sulfuric acid. A significantly higher ee was observed when polyphosphoric acid (PPA) was used instead. A remarkable correlation between the amount of PPA used and the ee of the product was revealed, namely, an increase in the ee upon decreasing the amount of PPA. This trend was paralleled by the formation of an increasing amount of a side-product upon lowering the amount of PPA. The racemization and formation of a side-product can be explained by an ipso -attack mechanism during the electrophilic aromatic ring-closure reaction. This mechanism was supported by a mechanistic study using a deuterium-labeled substrate.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] 1,3-Diethynylallenes: Stable Monomers, Length-Defined Oligomers, Asymmetric Synthesis, and Optical ResolutionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2007Matthijs K. J. ter Wiel Abstract A series of differently substituted 1,3-diethynylallenes (DEAs) have been synthesized, confirming that the previously introduced construction protocols tolerate a variety of functional groups. The new DEAs bear at least one polar group to facilitate enantiomer separations on chiral stationary phases and to allow further functionalization. They are thermally and environmentally stable compounds since bulky substituents next to the cumulene moiety suppress the tendency to undergo [2+2] cyclodimerization. A series of length-defined oligomers were obtained as mixtures of stereoisomers by oxidative coupling of a monomeric DEA under Glaser,Hay conditions. The electronic absorption data indicate a lack of extended ,-electron conjugation across the oligomeric backbone due to the orthogonality of the allenic ,-systems. Remarkably, even complex mixtures of stereoisomers only yield one single set of NMR signals, which underlines the low stereodifferentiation in acyclic allenoacetylenic structures. Optical resolution of DEAs represents an amazing challenge, and preliminary results on the analytical level are reported. Asymmetric synthesis by Pd-mediated SN2,-type cross-coupling of an alkyne to an optically pure bispropargylic precursor opens another promising route to optically active allenes with stereoselectivities currently reaching up to 78,% ee. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Effects of Extended Aryl-Substituted Bisoxazoline Ligands in Asymmetric Synthesis , Efficient Synthesis and Application of 4,4,-Bis(1-Naphthyl)-, 4,4,-Bis(2-Naphthyl)- and 4,4,-Bis(9-Anthryl)-2,2,-isopropylidenebis(1,3-oxazolines)EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2005Hester L. van Lingen Abstract The steric influence of extended aryl substituents on 2,2,-bis(1,3-oxazoline) ligands was investigated in a series of asymmetric catalytic reactions such as Mukaiyama aldol and Michael reactions, hetero-Diels,Alder processes, and allylic alkylation reactions. 4,4,-(2-Naphthyl)- and 4,4,-(9-anthryl)-substituted isopropylidene-bridged 2,2,-bis(1,3-oxazolines) were synthesized and their enantioselective and catalytic properties in combination with different metals evaluated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] First Asymmetric Synthesis and Determination of the Absolute Configuration of a Lignan Isolated from Virola sebiferaEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2005Dieter Enders Abstract The first asymmetric synthesis of a lignan isolated from the seeds of Virola sebifera, one of the most widely spread Myristicaceae species in Brazil, in four steps (48,% overall yield) and with excellent stereoselectivity (de, ee , 96,%) is described. The key step is the asymmetric Michael addition of a lithiated enantiopure ,-amino nitrile to an enone, followed by ,-methylation and cleavage of the amino nitrile. The absolute configuration of the naturally occurring 1,4-diketone was determined by polarimetry as well as by CD spectroscopy and quantum chemical calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] An Efficient Asymmetric Synthesis of 2-Substituted 1,4-Benzodiazepin-3-one as a Potential Molecular ScaffoldEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2005Nuria Cabedo Abstract 2-Substituted 1,4-benzodiazepine-2-one compounds (9,12) were obtained by a highly diastereoselective alkylation of a seven-membered ring benzolactam (8) in the presence of (R)-phenylglycinol as a chiral inductor. The corresponding acid derivative (16) afforded a conformationally constrained structure suitable for preparing peptidomimetic analogues useful as a novel molecular scaffold. After cleavage of the chiral appendage this approach might also lead efficiently to enantiomerically pure 2-substituted benzodiazepines (15). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Asymmetric Synthesis of Isoquinoline Derivatives from Amino AcidsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2005Oxana Sieck Abstract Reaction of isoquinolines 1 with N -arylsulfonylamino acid fluorides 2 provides a highly stereoselective access to new dihydroimidazo[2,1 -a]isoquinolin-3-ones 5 via intermediate N -acylisoquinolinium salts 3. Addition reactions to the en-amine double bond, such as hydrogenation or epoxidation with dimethyldioxirane, leads to tetrahydroimidazo[2,1 -a]isoquinoline-3-ones 6, 7 and oxiranes 8, respectively. Opening of the oxirane ring of the 8 with nucleophiles allows the synthesis of hydroxytetrahydroimidazo[2,1 -a]isoquinolin-3-ones 10 or 12 or of the polycyclic 1,4-dioxane 13 in high stereoselectivity. The regioselectivity of the oxiran ring opening depends on the kind of nucleophile and the conditions. Reaction of dihydroisoquinoline with O -TBDMS-mandelic acid chloride 15 leads to a tetrahydrooxazolo[2,3 -a]isoquinoline 17 with opposite facial selectivity as compared with dihydroimidazo[2,1 -a]isoquinolin-3-ones 5. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Asymmetric Synthesis of ,-Fluorinated ,-Amino Acid DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2005Deepak M. Shendage Abstract Asymmetric alkylation of (S)-Boc-BMI (1a, BMI = 2- tert -butyl-3-methylimidazolidin-4-one) and its ,-methyl derivative 1b with 2-fluoroallyl tosylate, subsequent mild acidic deprotection of the products 2a and 2b, and basic hydrolysis of the thus formed N -methylamides 4a and 4b gave (S)-2-amino-4-fluoropent-4-enoic acid (5a) and (S)-2-amino-4-fluoro-2-methylpent-4-enoic acid (5b). Basic hydrolysis of compound 4a was accompanied by partial racemization, which was overcome by applying a new stereoconservative deamidation procedure. The alkylated cis -configured product 2a formed under kinetic control epimerized on refluxing with 2 n NaOH to give the thermodynamically more stable trans isomer 9. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Asymmetric Synthesis of ,,,-Substituted ,-Sultones via Allylation of Chiral Lithiated SulfonatesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2003Dieter Enders Abstract The first auxiliary controlled asymmetric synthesis of enantiopure ,,,-substituted ,-sultones via ,-allylation of lithiated sulfonates by using 1,2:5,6-di- O -isopropylidene-,- D -allofuranose as chiral auxiliary is described. The high asymmetric inductions of the ,-allylations were reached in good to excellent yields. Successive epimerization-free cleavage of the auxiliary and diastereoselective ring closure of the sulfonic acid intermediates in a one-pot procedure led to the title compounds in good to excellent yields and diastereo- and enantiomeric excesses (de, ee , 98%). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Asymmetric Synthesis of Coordination Compounds: Back to the Roots.HELVETICA CHIMICA ACTA, Issue 10 2005Diastereoselective Synthesis of Simple Platinum(IV) Complexes No abstract is available for this article. [source] Asymmetric Synthesis of Maraviroc (UK-427,857)ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Gui-Ling Zhao Abstract The asymmetric synthesis of Maraviroc (UK-427,857), a chemochine receptor 5 (CCR-5) receptor antagonist, based on an expeditious organocatalytic enantioselective assembly of the chiral ,-amino aldehyde key fragment is presented. The reactions were performed on a gram-scale and allow for the rapid construction of new Maraviroc analogues. [source] Copper-Catalyzed Asymmetric 1,4-Hydroboration of Coumarins with Pinacolborane: Asymmetric Synthesis of DihydrocoumarinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Hyohyun Kim Abstract An efficient asymmetric addition of pinacolborane to 4-substituted coumarins proceeded with high enantioselectivity in the presence of a copper(I)-QuinoxP complex as a catalyst to produce the corresponding 1,4-hydroboration products. Treatment of the intermediates with electrophiles, without isolation, resulted in enantioenriched dihydrocoumarins. The utility of this protocol was demonstrated in the formal synthesis of biologically active molecules. [source] Catalytic Asymmetric Synthesis of Oxindoles Bearing a Tetrasubstituted Stereocenter at the C-3 PositionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Feng Zhou Abstract The 3,3,-disubstituted oxindole structural motif is a prominent feature in many alkaloid natural products, which include all kinds of tetrasubstituted carbon stereocenters, spirocyclic or not, all-carbon or heteroatom-containing. The catalytic asymmetric synthesis of the tetrasubstituted carbon stereocenter at the C-3 position of the oxindole framework integrates new synthetic methods and chiral catalysts, reflects the latest achievements in asymmetric catalysis, and facilitates the synthesis of sufficient quantities of related compounds as potential medicinal agents and biological probes. This review summarizes the recent progress in this area, and applications in the total synthesis of related bioactive compounds. [source] Asymmetric Synthesis of 2,3,4-Trisubstituted Functionalised Tetrahydrofurans via an Organocatalytic Michael Addition as Key StepADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Dieter Enders Abstract The organocatalytic Michael addition of various aldehydes to (2E,4E)-ethyl 5-nitropenta-2,4-dienoate has been achieved under the catalysis of diphenylprolinol trimethylsilyl ether furnishing the products in good to excellent yields (61,94%) and high stereoselectivities (dr up to >98:2, ee=97 to >99%). Starting from these Michael adducts, 2,3,4-trisubstituted functionalized tetrahydrofurans are available in two steps by reduction of the aldehyde followed by an intramolecular oxa-Michael addition in good yields (54,76%) and stereoselectivities (dr up to >95:5, ee=97 to >99%). [source] Asymmetric Synthesis with Silicon-Based Bulky Amino OrganocatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Li-Wen Xu Abstract Recent years have witnessed an explosive growth in the field of amino organocatalysis, especially in asymmetric enamine and iminium catalysis. Except for the obvious interaction between organocatalyst and substrate, the impact of bulky side group ons stereoselectivity is not as simple as one could imagine. Within the development of bulky site-stereoselective organocatalysts, functional silyl organocatalysts with a bulky silicon group are promising and meet the high standards of modern synthetic methods. This review focuses on the recent advances in the synthetic applications of silicon-based, bulky amino organocatalysts in which catalysts containing an organosilicon moiety or group play a formative role in controlling both the course of the reaction as well as the stereoselectivity. [source] Highly Enantioselective Biginelli Reaction Promoted by Chiral Bifunctional Primary Amine-Thiourea Catalysts: Asymmetric Synthesis of DihydropyrimidinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Yangyun Wang Abstract The diastereospecific formation of dihydropyrimidines (DHPMs) has been achieved in moderate to high yields with up to 99% ee by a Biginelli reaction. The reaction was performed by using a combined catalyst consisting of a chiral bifunctional primary amine-thiourea 9f and a Brønsted acid with tert -butylammonium trifluoroacetate (t- BuNH2,TFA) as additive in dichloromethane at room temperature. The possible mechanism for the reaction has been proposed to explain the origin of the activation and the asymmetric induction. [source] Catalytic Asymmetric Synthesis of Branched Chiral Allylic Phenyl Ethers from (E)-Allylic AlcoholsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Angela Abstract The first di-,-amidate dipalladium complexes and a new di-,-carboxylate dipalladium complex of the COP (cobalt oxazoline palladacycle) palladium(II) catalyst family are reported and characterized crystallographically. The di-,-amidate complex 3 and its enantiomer (ent - 3) are the first asymmetric catalysts that allow commercially available, or readily accessible, (E)-2-alken-1-ols to be transformed to enantioenriched branched allylic aryl ethers upon reaction of their trichloroacetimidate derivatives with phenols. The 3-aryloxy-1-alkene products are formed in high enantiomeric purity (typically 90,98% ee) and useful yields (61,88%). [source] Organocatalytic Asymmetric Synthesis of Protected ,,,-Diamino AcidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Zugui Shi Abstract In the presence of the readily available quinine-derived catalyst 4d, highly diastereo- and enantioselective Mannich reactions of tosyl-protected imines and ,-isothiocyanato imides proceeded to afford the protected ,,,-diamino acids, useful building blocks for natural products and biologically active compounds, in good to excellent yields. [source] Asymmetric Synthesis of ,,,-Diaminophosphonic Acid Derivatives with a Catalytic Enantioselective Mannich ReactionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Robert Djiokeng Momo Abstract Optically active ,,,-diaminophosphonic acid derivatives were obtained from the catalytic enantioselective Mannich reaction of phosphoglycine Schiff bases with N -Boc-imines, generated in situ from ,-amido sulfones. 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