- Enantioconvergent Cu-Catalyzed Radical C-N Coupling of Racemic Secondary Alkyl Halides to Access α-Chiral Primary Amines
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α-Chiral alkyl primary amines are virtually universal synthetic precursors for all other α-chiral N-containing compounds ubiquitous in biological, pharmaceutical, and material sciences. The enantioselective amination of common alkyl halides with ammonia is appealing for potential rapid access to α-chiral primary amines, but has hitherto remained rare due to the multifaceted difficulties in using ammonia and the underdeveloped C(sp3)-N coupling. Here we demonstrate sulfoximines as excellent ammonia surrogates for enantioconvergent radical C-N coupling with diverse racemic secondary alkyl halides (>60 examples) by copper catalysis under mild thermal conditions. The reaction efficiently provides highly enantioenrichedN-alkyl sulfoximines (up to 99% yield and >99% ee) featuring secondary benzyl, propargyl, α-carbonyl alkyl, and α-cyano alkyl stereocenters. In addition, we have converted the masked α-chiral primary amines thus obtained to various synthetic building blocks, ligands, and drugs possessing α-chiral N-functionalities, such as carbamate, carboxylamide, secondary and tertiary amine, and oxazoline, with commonly seen α-substitution patterns. These results shine light on the potential of enantioconvergent radical cross-coupling as a general chiral carbon-heteroatom formation strategy.
- Cheng, Jiang-Tao,Dong, Xiao-Yang,Gu, Qiang-Shuai,Li, Zhong-Liang,Liu, Juan,Liu, Xin-Yuan,Luan, Cheng,Wang, Fu-Li,Wang, Li-Lei,Yang, Ning-Yuan,Zhang, Yu-Feng
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supporting information
p. 15413 - 15419
(2021/09/30)
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- Stereoselective synthesis of oxazolidin-2-ones via an asymmetric aldol/curtius reaction: Concise total synthesis of (?)-cytoxazone
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Herein, we are reporting an efficient approach toward the synthesis of 4,5-disubstituted oxazolidin-2-one scaffolds. The developed approach is based on a combination of an asymmetric aldol and a modified Curtius protocol, which uses an effective intramolecular ring closure to rapidly access a range of oxazolidin-2-one building blocks. This strategy also permits a straightforward and concise asymmetric total synthesis of (?)-cytoxazone. Consisting of three steps, this is one of the shortest syntheses reported to date. Ultimately, this convenient platform would provide a promising method for the early phases of drug discovery.
- Choi, Hosam,Choi, Joohee,Jang, Hanho,Lee, Kiyoun
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- A new type of L-Tertiary leucine-derived ligand: Synthesis and application in Cu(II)-catalyzed asymmetric Henry reactions
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A new series of Schiff bases derived from amino acids were developed as chiral ligands for Cu(II)-catalyzed asymmetric Henry reactions. The optimum ligand 7d exhibited outstanding catalytic efficiency in the Cu(II)-catalyzed asymmetric Henry additions of four nitroalkanes to different kinds of aldehydes to produce 76 desired adducts in high yields (up to 96%) with excellent enantioselectivities, up to 99% enantiomeric excess (ee).
- Cai, Zedong,Lan, Ting,Ma, Pengfei,Zhang, Jingfang,Yang, Qingqing,He, Wei
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- Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions
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Oxidative alkene difunctionalization reactions are important in synthetic organic chemistry because they can install polar functional groups onto simple non-polar alkene moieties. Many of the most common methods for these reactions rely upon the reactivity of pre-oxidized electrophilic heteroatom donors that can often be unstable, explosive, or difficult to handle. Herein, we describe a method for alkene oxyamination and diamination that utilizes simple carbamate and urea groups as nucleophilic heteroatom donors. This method uses a tandem copper–photoredox catalyst system that is operationally convenient. The identity of the terminal oxidant is critical in these studies. Ag(I) salts proved to be unique in their ability to turn over the copper cocatalyst without deleteriously impacting the reactivity of the organoradical intermediates.
- Reed, Nicholas L.,Herman, Madeline I.,Miltchev, Vladimir P.,Yoon, Tehshik P.
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supporting information
p. 351 - 356
(2019/02/20)
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- Chiral 1,3,2-Diazaphospholenes as Catalytic Molecular Hydrides for Enantioselective Conjugate Reductions
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Secondary 1,3,2-diazaphospholenes have a polarized P?H bond and are emerging as molecular hydrides. Herein, a class of chiral, conformationally restricted methoxy-1,3,2-diazaphospholene catalysts is reported. We demonstrate their catalytic potential in asymmetric 1,4-reductions of α,β-unsaturated carbonyl derivatives, including enones, acyl pyrroles, and amides, which proceeded in enantioselectivities of up to 95.5:4.5 e.r.
- Miaskiewicz, Solène,Reed, John H.,Donets, Pavel A.,Oliveira, Caio C.,Cramer, Nicolai
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supporting information
p. 4039 - 4042
(2018/03/13)
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- Kinetic resolution of racemic amino alcohols through intermolecular acetalization catalyzed by a chiral Bronsted acid
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The kinetic resolution of racemic secondary alcohols is a fundamental method for obtaining enantiomerically enriched alcohols. Compared to esterification, which is a well-established method for this purpose, kinetic resolution through enantioselective intermolecular acetalization has not been reported to date despite the fact that the formation of acetals is widely adopted to protect hydroxy groups. By taking advantage of the thermodynamics of acetalization by the addition of alcohols to enol ethers, a highly efficient kinetic resolution of racemic amino alcohols was achieved for the first time and in a practical manner using a chiral phosphoric acid catalyst.
- Yamanaka, Takuto,Kondoh, Azusa,Terada, Masahiro
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supporting information
p. 1048 - 1051
(2015/02/19)
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- Open tubular molecular imprinted polymer fabricated in silica capillary for the chiral recognition of neutral enantiomers in capillary electrochromatography
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In this study, we have expanded the applicability of the pre-established generalized preparation protocol to MIPs with a neutral template. The (4S,5R)-4-methyl-5-phenyl-2-oxazolidinone MIP layer was formed inside a pretreated and silanized fused silica capillary, and its chiral separation performance was examined. Optimization of chiral separation was also carried out. This is the very first report of somewhat successful application of the generalized preparation protocol to a MIP with a genuine neutral template. Copyright
- Yang, Song Hee,Zaidi, Shabi Abbas,Cheong, Won Jo,ALOthman, Zeid A.,ALMajid, Abdullah M.
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scheme or table
p. 1664 - 1668
(2012/07/13)
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- A ring-closing metathesis-based approach to the synthesis of (+)-tetrabenazine
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A modular stereoselective synthesis of the vesicular monoamine transport inhibitors (+)-tetrabenazine ((+)-1) and (+)-α-dihydrotetrabenazine ((+)-2) has been developed. The approach is based on amine 4 and acid 5 as the key building blocks, which were elaborated into macrolactam 3 by amide coupling and a subsequent highly E-selective RCM reaction. Macrolactam 3 could be converted into tetrabenazine in three known steps.
- Johannes, Manuel,Altmann, Karl-Heinz
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supporting information; experimental part
p. 3752 - 3755
(2012/09/07)
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- Synthesis of 2-Arylethylamines by the Curtius Rearrangement
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2-Arylethylamine derivatives were synthesized using the Curtius reaction and with three different methods of preparing the acyl azide functional group. Carbamates derived from isocyanate were convenient protecting groups for alkylation of amines. Starting from benzaldehyde, amphetamine was prepared in three steps through an oxazolidin-2-one intermediate in 62% overall yield. Copyright Taylor & Francis Group, LLC.
- Schulze, Matthias
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experimental part
p. 1461 - 1476
(2010/07/08)
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- Stereoselective synthesis of a monocyclic peloruside A analogue
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Chemical Equation Presentation The stereoselective synthesis of the monocyclic peloruside A analogue 4 has been achieved, following a new efficient approach for the introduction of the side chain, involving a late-stage addition of vinyl lithium species 7a to aldehyde 8. Further key steps are a highly diastereoselective allyltitanation reaction and a RCM-based macrocyclization.
- Wulischleger, Christoph W.,Gertsch, Juerg,Altmann, Karl-Heinz
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supporting information; experimental part
p. 1120 - 1123
(2010/06/13)
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- Asymmetric synthesis of amlnocyclopropanes and N-cyclopropylamino alcohols through direct amidocyclopropanation of alkenes using chiral organozinc carbenoids
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Chiral N-(diethoxymethyl)oxazolidinones, prepared from the corresponding oxazolidinones by heating in trielhyl orthoformate, can be used as organozinc carbenoid precursors for the direct enantioselective amidocyclopropanation of alkenes. The reaction is successful with a wide range of oxazolidinones and alkenes and proceeds with moderate to excellent yield and stereoselectivity. In most cases the trans/exo amidocyclopropane product, is favoured, although certain cyclic alkenes such as indene favour the formation of the endo cyclopropane. The products can be readily elaborated to produce cyclopropylamino alcohols and amino acids. Wiley-VCH Verlag GmbH & Co. KGaA.
- Begis, Guillaume,Cladingboel, David E.,Jerome, Laure,Motherwell, William B.,Sheppard, Tom D.
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experimental part
p. 1532 - 1548
(2009/09/08)
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- METHOD OF PREPARING PSEUDONOREPHEDRINE
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A method of making high diastereoselective and enantiomerically pure pseudonorephedrine and the hitherto unknown compound (1R,2R) pseudonorephedrine.
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Page/Page column 4
(2008/06/13)
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- Asymmetric tandem Michael-Aldol reactions between 3-cinnamoyloxazolidine-2- thiones and aldehydes
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Reactions between chiral 3-cinnamoyl-4-methyl-5-phenyl-1,3-oxazolidine-2- thiones and aromatic aldehydes in the presence of BF3·Et 2O diastereoselectively produced tricyclic compounds incorporating a bridgehead carbon bound to four heteroatoms in high yields. Four stereocenters were induced during the reaction. The tricyclic products were transformed into propane-1,3-diols bearing three consecutive stereocenters by acid hydrolysis, S-methylation, and reductive removal of the chiral auxiliary.
- Kinoshita, Hironori,Osamura, Takashi,Mizuno, Kazumi,Kinoshita, Sayaka,Iwamura, Tatsunori,Watanabe, Shin-Ichi,Kataoka, Tadashi,Muraoka, Osamu,Tanabe, Genzoh
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p. 3896 - 3904
(2008/02/06)
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- Total synthesis and antitumor activity of ZK-EPO: The first fully synthetic epothilone in clinical development
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Going to trial: From about 350 active epothilone analogues synthesized by a highly convergent synthesis, one (ZK-EPO, see picture) has been chosen for clinical development on the basis of its outstanding preclinical data. This compound exhibits higher activity and efficacy than taxanes (e.g. paclitaxel) and second-generation epothilones, a fast and efficient cellular uptake, no recognition by efflux mechanisms, and an improved therapeutic window. (Chemical Equation Presented)
- Klar, Ulrich,Buchmann, Bernd,Schwede, Wolfgang,Skuballa, Werner,Hoffmann, Jens,Lichtner, Rosemarie B.
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p. 7942 - 7948
(2007/10/03)
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- Remarkably efficient charcoal-promoted ring-closing carbonylations
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An efficient, versatile and practical gram-scale preparation of oxazolidinone, imidazolidinone and dioxolanone is achieved. Georg Thieme Verlag Stuttgart.
- Alouane, Nacira,Boutier, Audrey,Baron, Cyriella,Vrancken, Emmanuel,Mangeney, Pierre
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p. 885 - 889
(2007/10/03)
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- Reactivity difference between diphosgene and phosgene in reaction with (2,3-anti)-3-amino-1,2-diols
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In reactions of (2,3-anti)-3-amino-1,2-diols with diphosgene and phosgene and their conversion into 1,3-oxazolidin-2-ones, some differences in the stereochemistry of the reactions have been found with these two reagents. The reactions with phosgene afforded the expected cis-oxazolidinones, and in the reaction with diphosgene under the same reaction conditions, the trans-oxazolidinones were also obtained.
- Hamdach,El Hadrami,Gil,Zaragozá,Zaballos-García,Sepúlveda-Arques
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p. 6392 - 6397
(2007/10/03)
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- Stereoselective conjugate radical additions: Application of a fluorous oxazolidinone chiral auxiliary for efficient tin removal
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(Chemical Equation Presented) A series of asymmetric free-radical-mediated intermolecular conjugate additions using a fluorous oxazolidinone chiral auxiliary has been completed. The fluorous auxiliary facilitated product isolation using fluorous solid phase extractions (FSPE), effectively removing excess organic and organometallic reagents. Parallel reactions carried out with a similar but nonfluorous norephedrine-derived oxazolidinone demonstrated the superior stereoselectivity and purification obtainable with the fluorous chiral auxiliary.
- Hein, Jason E.,Zimmerman, Jake,Sibi, Mukund P.,Hultin, Philip G.
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p. 2755 - 2758
(2007/10/03)
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- Aurilide, a cytotoxic depsipeptide from the sea hare Dolabella auricularia: Isolation, structure determination, synthesis, and biological activity
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The bioassay-guided fractionation of the cytotoxic constituents of the Japanese sea hare Dollabella auricularia led to the isolation of aurilide (1), a 26-membered cyclodepsipeptide. The gross structure of 1 was established by spectroscopic analysis including 2D NMR techniques. The absolute stereostructure was determined by chiral HPLC analysis of acid hydrolysates of 1 and by the enantioselective synthesis of a degradation product arising from a dihydroxylated fatty acid portion. The enantioselective synthesis of 1 was achieved in 12% overall yield (16 steps) and confirmed the absolute stereostructure of 1. The cytotoxicity of 1 was evaluated using a synthetic sample, which was found to exhibit potent cytotoxicity against HeLa S 3 cells with an IC50 of 0.011 μg/mL. Further biological and pharmacological studies of 1 have been carried out by using synthetic 1. Graphical abstract.
- Suenaga, Kiyotake,Mutou, Tsuyoshi,Shibata, Takunobu,Itoh, Takashi,Fujita, Tatsuya,Takada, Noboru,Hayamizu, Kozue,Takagi, Masaki,Irifune, Taiji,Kigoshi, Hideo,Yamada, Kiyoyuki
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p. 8509 - 8527
(2007/10/03)
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- EPOTHILONE DERIVATIVES, METHOD FOR PRODUCING SAME AND THEIR PHARMACEUTICAL USE
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This invention relates to the new epothilone derivatives of general formula I, 1in which substituents Y, Z R2a, R2b, R3, R4a, R4b, D—E, R5, R6, R7, R8 and X have the meanings that are indicated in more detail in the description. The new compounds interact with tubulin by stabilizing microtubuli that are formed. They are able to influence the cell-splitting in a phase-specific manner and are suitable for treating malignant tumors, for example, ovarian, stomach, colon, adeno-, breast, lung, head and neck carcinomas, malignant melanomas, acute lymphocytic and myelocytic leukemia. In addition, they are suitable for anti-angiogenesis therapy as well as for treatment of chronic inflammatory diseases (psoriasis, arthritis). To avoid uncontrolled proliferation of cells and for better compatibility of medical implants, they can be applied or introduced into polymer materials. The compounds according to the invention can be used alone or to achieve additive or synergistic actions in combination with other principles and classes of substances that can be used in tumor therapy.
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- A novel nucleophilic attack to N-enoyl oxazolidinethiones
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The oxazolidinethione synthon can act as a chiral auxiliary and nucleophile (S-) carrier molecule simultaneously. Surprisingly, the thiolate attacks N-enoyl oxazolidinethiones producing a new heterocycle, as established by X-ray analysis.
- Ortiz, Aurelio,Quintero, Leticia,Mendoza, Guadalupe,Bernès, Sylvain
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p. 5053 - 5055
(2007/10/03)
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- Chemoselective debezylation of the N-1-phenylethyl group in 2-oxazolidinones by the anisole-methanesulfonic acid system
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The chemoselective removal of N-1-phenylethyl group in 2-oxazolidinones by the anisole-methanesulfonic acid system was investigated. Optically active 4,5-cis- and 4,5-trans-diphenyl-2-oxazolidinones (1a-d) were easily synthesized from dl-stilbene oxides (trans- and cis-7a) using this debenzylation.
- Sugiyama, Shigeo,Morishita, Kenji,Chiba, Mariko,Ishii, Keitaro
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p. 637 - 648
(2007/10/03)
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- Stereoselective synthesis of pamamycin-607
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A macrodiolide antibiotic pamamycin-607 was synthesized by joining two hydroxy acid components. Three cis-2, 5-disubstituted tetrahydrofuran rings in the molecule were stereoselectively prepared by radical cyclization reactions of β-alkoxyvinyl ketone intermediates and a β-alkoxymethacrylate substrate. The key step of the synthesis is characterized by the predominant threo product formation in the radical cyclization reaction of a β-alkoxymethacrylate intermediate.
- Jeong, Eun Jeong,Kang, Eun Joo,Sung, Lee Taek,Hong, Sung Kil,Lee, Eun
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p. 14655 - 14662
(2007/10/03)
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- The reaction of β-amino alcohols with 1,1′ -carbonyldiimidazole - Influence of the nitrogen substituent on the reaction course
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The reaction of β-amino alcohols with 1,1′carbonyldiimidazole in dichloromethane is affected by the size of the nitrogen substituent. 1,3-Oxazolidin-2-ones are exclusively obtained from N-H, N-methyl and N-arylmethyl derivatives. O-(1-Imidazolyl)carbonyl derivatives are formed as intermediates from N-[1-(2-pyridyl)alkyl]-(S)-valinol and are mainly or exclusively converted into aziridines in the presence of water, although the cyclization is impeded by large N-substituents such as triphenylmethyl.
- Cutugno, Sara,Martelli, Gianluca,Negro, Lucia,Savoia, Diego
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p. 517 - 522
(2007/10/03)
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- Enantioselective synthesis of 2-substituted 3-aminopropanoic acid (β-alanine) derivatives which are β-analogues of aromatic amino acids
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3-Aminopropanoic acid derivatives with a phenyl, 4-hydroxyphenyl, benzyl or indol-3-yl substituent at C-2 can be prepared enantioselectively by routes involving electrophilic attack of synthetic equivalents of [H2NCH2]+ upon enolates derived from chiral 3-acyl-1,3-oxazolidin-2-ones. tert-Butyl bromoacetate may be used as the electrophile, with subsequent introduction of nitrogen through the Curtius reaction, using the sequence of reagents (i) CF3CO2H; (ii) (PhO)2P(O)N3, Et3N, PhCH2OH; alternatively, direct electrophilic reaction with 1-[N-(benzyloxycarbonyl)aminomethyl]benzotriazole 4c or benzyl N-(acetoxymechyl)carbamate 2d introduces a protected aminomethyl group in a single step.
- Arvanitis, Elena,Ernst, Holger,Ludwig, Alice A.,Robinson, Andrew J.,Wyatt, Peter B.
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p. 521 - 528
(2007/10/03)
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- Palladium-catalyzed intramolecular allylic alkylation reaction in marine natural product synthesis: Enantioselective synthesis of (+)-methyl pederate, a key intermediate in syntheses of mycalamides
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A novel preparation of (+)-methyl pederate (4), a key intermediate in syntheses of mycalamides (1), marine natural products from a New Zeland sponge of the genus Mycale, is described. The key step involves palladium- catalyzed intramolecular allylic alkylation of the carbonate 21, derived from (+)-(4R,5R,E)-5-(tert-butyldimethylsiloxy)-4-methyl-2-hexenol (13), yielding lactones 5 in 87% yield. Demethoxycarbonylation of the cyclization products 5 and further functional group transformations led to (+)-methyl pederate (4).
- Toyota, Masahiro,Hirota, Masako,Nishikawa, Youichi,Fukumoto, Keiichiro,Ihara, Masataka
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p. 5895 - 5902
(2007/10/03)
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- Synthesis of 2-Oxo-Oxazolidines and -Thiazolidines from the Corresponding 2-Thioxo Compounds
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2-Thioxo-oxazolidines and -thiazolidines are easily converted by reaction with an epoxide under acidic conditions into the corresponding 2-oxo compounds.
- Calo, Vinzenzo,Nacci, Angelo,Volpe, Angela
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p. 283 - 286
(2007/10/03)
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- Aplyronine A, a potent antitumor substance of marine origin, aplyronines B and C, and artificial analogues: Total synthesis and structure-cytotoxicity relationships
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The enantioselective total synthesis of aplyronine A (1), a potent antitumor substance of marine origin, was achieved by a convergent approach. Three segments 4, 5, and 6, corresponding to the C5-C11, C21-C27, and C28-C34 portions of aplyronine A (1), were prepared using the Evans aldol reaction and the Sharpless epoxidation as key steps. The coupling reaction of 4 with iodide 7 followed by Julia olefination with sulfone 8 gave the C5-C20 segment 9, while the Julia coupling reaction between segments 5 and 6 provided the C21-C34 segment 10. Julia olefination between segments 9 and 10 and the subsequent four-carbon homologation reaction led to seco acid 83, which was converted into aplyronine A (1) by Yamaguchi lactonization followed by the introduction of two amino acids. The use of the [(3,4-dimethoxybenzyl)oxy]methyl group as a protecting group for the hydroxyl at C29 was crucial for this synthesis. The enantioselective synthesis of two natural congeners, aplyronines B (2) and C (3), was also carried out using the intermediates for the synthesis of 1, which determined the absolute stereostructures of 2 and 3 unambiguously. To study the structure-cytotoxicity relationships of aplyronines, artificial analogues of 1 were synthesized and their cytotoxicities were evaluated: the trimethylserine moiety, two hydroxyl groups, and the side chain portion in 1 turned out to be important in the potent cytotoxicity shown by 1. Biological studies with aplyronine A (1) showed that 1 inhibited polymerization of G-actin to F-actin and depolymerized F-actin to G-actin.
- Kigoshi, Hideo,Suenaga, Kiyotake,Mutou, Tsuyoshi,Ishigaki, Takeshi,Atsumi, Toshiyuki,Ishiwata, Hiroyuki,Sakakura, Akira,Ogawa, Takeshi,Ojika, Makoto,Yamada, Kiyoyuki
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p. 5326 - 5351
(2007/10/03)
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- Stereoselective synthesis of 3-substituted 4-(formyloxy)-2-azetidinones by the unusual Baeyer-Villiger reaction of β-lactam aldehydes. Scope and synthetic applications
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The Baeyer-Villiger oxidation of 4-formyl-β-lactams 1 with m-CPBA gave 4-(formyloxy) β-lactams 2 in a simple, efficient, and totally stereoselective process. This reaction is one of the scarce examples of the preferred migration of a carbon moiety in an aliphatic aldehyde. The influence of the substituents at N1 and C3 of the four-membered ring in the Baeyer-Villiger rearrangement has been studied. Thus, alkyl, alkenyl, aryl, and alkyloxy 3-substituted-1-(p-anisyl)-2-azetidinones 1 form exclusively 4-(formyloxy) β-lactams 2. Amide or acetoxy substituents at C3 of the four membered ring produce mixtures of 4-(formyloxy) β-lactams 2 and 4-carboxy β-lactams 5. The exclusive formation of carboxy derivatives is observed sometimes for 1-alkyl-substituted-2-azetidinones 1. 4-(Formyloxy) β-lactams 2 are suitable starting materials to prepare different 4-unsubstituted β-lactams 9 using β-hydroxy amides 8 as isolable intermediates. The overall transformation 4-formyl-2-azetidinone to 4-unsubstituted β-lactam is an easy and convenient stereoselective route to these interesting types of compounds.
- Alcaide, Benito,Alyt, Moustafa F.,Sierra, Miguel A.
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p. 8819 - 8825
(2007/10/03)
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- (R)-(+)-3-Amino-2-phenylpropanoic Acid: a Revised Absolute Configuration based on an Enantioselective Synthesis and an X-Ray Crystal Structure of the Salt with (1S)-(+)-Camphor-10-sulfonic Acid
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Amidoalkylation of the lithium enolate of (4S,5R)-4-methyl-5-phenyl-3-(phenylacetyl)oxazolidin-2-one 5 by 1-(N-benzyloxycarbonylaminomethyl)benzotriazole 2c, followed by cleavage of the oxazolidinone chiral auxiliary and of the N-benzyloxycarbonyl group, gave (R)-(+)-3-amino-2-phenylpropanoic acid 1, the absolute configuration of which was determined by X-ray crystallography on the salt 8 with (1S)-(+)-camphor-10-sulfonic acid.
- D'Souza, Alice A.,Motevalli, Majid,Robinson, Andrew J.,Wyatt, Peter B.
-
-
- Preparation of 1,2-Aminols from Cyanohydrins via N-Diisobutylaluminium Imines.
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The N-aluminium imines derived from cyanohydrins have been used in the synthesis of α-amino alcohols with high diastereoselectivity.
- Cainelli, Gianfranco,Panunzio, Mauro,Contento, Michele,Giacomini, Daria,Mezzina, Elisabetta,Giovagnoli, Daniela
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p. 3809 - 3826
(2007/10/02)
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- ALUMINUM-MEDIATED ONE-POT CONVERSION OF α-AMINO ACID ESTERS TO THREO 2-AMINO ALCOHOLS WITH HIGH DIASTEREOSELECTIVITY
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Reduction of N-Cbz α-amino acid esters with DIBAl-H, followed by treatment with Grignard reagent in a one-pot manner gave the corresponding threo 2-amino alcohols with high diastereoselectivity without racemization. KEYWORDS 2-amino alcohol; α-amino acid ester; DIBAL-H reduction; α-amino aldehyde; chelation controll; diastereoselective synthesis; one-pot synthesis
- Kano, Shinzo,Yuasa, Yoko,Yokomatsu, Tsutomu,Shibuya, Shiroshi
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p. 2867 - 2869
(2007/10/02)
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- A NEW FACILE DIASTEREOCONVERSION OF 2-AMINO ALCOHOLS INVOLVING A NOVEL CYCLOCARBAMATION
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A new practical method for diastereoconversion of 2-amino alcohols was performed by treatment on N-Cbz- derivatives with trifluoromethanesulfonic anhydride or thionyl chloride, followed by ring cleavage of the resulting oxazolidin-2-ones
- Kano, Shinzo,Yokomatsu, Tsutomu,Iwasawa, Haruo,Shibuya, Shiroshi
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p. 6331 - 6334
(2007/10/02)
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- α-Amino Acids as Chiral Educts for Asymmetric Products. Amino Acylation with N-Acylamino Acids
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α-N-Acylamino acids have been developed as useful reagents for the preparation of optically pure α-aminoalkylaryl ketones.Protection of the amino group as either the ethoxycarbonyl or benzenesulfonyl derivative allows alanine to serve as an effective educt for the chirally specific synthesis of a variety of structures containing the phenylethylamine backbone.Benzene undergoes Friedel-Crafts acylation with the N-acylalanine acid chloride.Catalyst complexation with oxagenated aromatics, however, prohibits acylation of aryl ethers.An arylmetallo reaction scheme overcomes this problem and also affords regiospecificity not attainable in conventional acylations.As examples, optically pure ephedrines and amphetamines were directly synthesized without recourse to resolution since the chirality of the amino acid educt was entirely conserved throughout the process.
- Buckley, Thomas F.,Rapoport, Henry
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p. 6157 - 6163
(2007/10/02)
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