- Palladium-Catalyzed Stereoselective Cyclization of in Situ Formed Allenyl Hemiacetals: Synthesis of Rosuvastatin and Pitavastatin
-
A diastereoselective palladium-catalyzed cyclization of allenyl hemiacetals is described. It permits the selective synthesis of 1,3-dioxane derivatives, precursors for syn-configured 1,3-diols which make an appearance in all of the statin representatives. The reaction allows the total synthesis of Rosuvastatin and Pitavastatin in a straightforward fashion.
- Spreider, Pierre A.,Breit, Bernhard
-
p. 3286 - 3290
(2018/06/11)
-
- Stereoselective α-Hydroxylation of Amides Using Oppolzer's Sultam as Chiral Auxiliary
-
An Oppolzer's sultam-based highly stereoselective α-hydroxylation of amides was developed to deliver the desired products in good yield and excellent diastereoselectivity (>20/1). The generally crystalline products and the recyclability of the chiral auxiliary illustrate the practicability and scalability of the current approach.
- Zhang, Lumin,Zhu, Lili,Yang, Jun,Luo, Jisheng,Hong, Ran
-
p. 3890 - 3900
(2016/05/24)
-
- Tosvinyl and besvinyl as protecting groups of imides, azinones, nucleosides, sultams, and lactams. Catalytic conjugate additions to tosylacetylene
-
The use of the 2-(4-methylphenylsulfonyl)-ethenyl (tosvinyl, Tsv) group for the protection of the NH group of a series of imides, azinones (including AZT), inosines, and cyclic sulfonamides has been examined. The Tsvprotected derivatives are obtained in excellent yields by conjugate addition to tosylacetylene (ethynyl p-tolyl sulfone). The stereochemistry of the double bond can be controlled at will: with only 1 mol % of Et3N or with catalytic amounts of NaH, the Z stereoisomers are generated almost exclusively, while the E isomers are obtained using a stoichiometric amount of DMAP. Analogous phenylsulfonylvinyl-protected groups (with the besvinyl or Bsv group instead of Tsv) are obtained stereospecifically by reaction with (Z)- or (E)-bis(phenylsulfonyl)ethene. For lactams and oxazolidinones, this last method is much better. The Tsv and Bsv groups are stable in the presence of non-nucleophilic bases and to acids. They can be removed highly effectively via a conjugate addition-elimination mechanism using pyrrolidine or sodium dodecanethiolate as nucleophiles.
- Petit, Elena,Bosch, Llus,Font, Joan,Mola, Laura,Costa, Anna M.,Vilarrasa, Jaume
-
p. 8826 - 8834
(2015/01/08)
-
- Amphidinolide B: Total synthesis, structural investigation, and biological evaluation
-
The total syntheses of amphidinolide B1 and the proposed structure of amphidinolide B2 have been accomplished. Key aspects of this work include the development of a practical, non-transition-metal-mediated method for the construction of the C13-C15 diene, the identification of α-chelation and dipole minimization models for diastereoselective methyl ketone aldol reactions, the discovery of a spontaneous Horner-Wadsworth-Emmons macrocyclization strategy, and the development of a novel late stage method for construction of an allylic epoxide moiety. The originally proposed structure for amphidinolide B2 and diastereomers thereof display potent antitumor activities with IC50 values ranging from 3.3 to 94.5 nM against human solid and blood tumor cells. Of the different stereoisomers, the proposed structure of amphidinolide B2 is over 12-fold more potent than the C8,9-epimer and C18-epimer in human DU145 prostate cancer cells. These data suggest that the epoxide stereochemistry is a significant factor for anticancer activity.
- Lu, Liang,Zhang, Wei,Nam, Sangkil,Horne, David A.,Jove, Richard,Carter, Rich G.
-
p. 2213 - 2247
(2013/05/09)
-
- A facile, inexpensive and scalable route to thiol-protected α-methyl cysteine
-
A facile, scalable synthesis of α-methyl cysteine with three alternate thiol protecting groups (trityl, allyl and tert-butyl) is described. The thiol-protected amino acids are obtained in six steps from l-cysteine ethyl ester and are ideally suited for a range of natural product and solid-phase peptide synthesis applications. Georg Thieme Verlag Stuttgart - New York.
- Johnston, Heather J.,Hulme, Alison N.
-
supporting information
p. 591 - 594
(2013/04/10)
-
- Stereoselective synthesis of (3S,5S,6S)-tetrahydro-6-isopropyl-3,5- dimethylpyran-2-one; A C5-epimer of a component of a natural sex pheromone of the wasp Macrocentrus grandii, the larval parasitoid of the European corn borer Ostrinia nubilalis
-
(3S,5S,6S)-Tetrahydro-6-isopropyl-3,5-dimethylpyran-2-one, a C5-epimer of a component of the natural sex pheromone of the wasp Macrocentrus grandii, the larval parasitoid of the European corn borer Ostrinia nubilalis, was synthesized starting from methyl l-valinate. The transformation includes a Kulinkovich cyclopropanation reaction, a cationic cyclopropyl-allyl rearrangement of cyclopropyl methanesulfonate, a diastereoselective alkylation of Oppolzer's (N-propionyl)-(2R)-bornane-10,2-sultam and a diastereoselective hydrogenation using Wilkinson's catalyst as the key steps.
- Shklyaruck, Denis,Matiushenkov, Evgenii
-
experimental part
p. 1448 - 1454
(2011/11/12)
-
- Efficacious preparation of Oppolzer's glycylsultam via the Delepine reaction
-
A new preparative route to Oppolzer's glycylsultam, the 'NC' component in the asymmetric [C+NC+CC] coupling reaction leading to functionalized pyrrolidines, is described. The synthesis features a novel application of the Delepine reaction, providing a saf
- Isleyen, Alper,Gonsky, Carolyn,Ronald, Robert C.,Garner, Philip
-
experimental part
p. 1261 - 1264
(2009/12/07)
-
- Process for Production of Optically Active Carboxlic Acid Compound
-
An optically active acylated camphorsultam can be hydrolyzed with an aqueous solution of an alkaline earth metal hydroxide in the presence of a branched alkanol, to give a corresponding optically active carboxylic acid compound in safely and inexpensively
- -
-
Page/Page column 6
(2009/05/28)
-
- Diastereoselective allylation of N-glyoxyloyl-(2R)-bornane-10,2-sultam and (1R)-8-phenylmenthyl glyoxylate: Synthesis of (2S,4S)-2-hydroxy-4-hydroxymethyl- 4-butanolide
-
The diastereoselective addition of allylsilanes and allylstannanes to N-glyoxyloyl-(2R)-bornane-10,2-sultam 1 and (1R)-8-phenylmenthyl glyoxylate 7 in the presence of Lewis acids has been studied. We obtained diastereoselectivities up to 84% and 94% for the allylation of 2 and 7, respectively. The application of the allylation products of 1 or 2 in the synthesis of 4-butanolides, for example (2S,4S)-2-hydroxy-4-hydroxymethyl-4- butanolide 13 is presented.
- Kiegiel, Katarzyna,Balakier, Tomasz,Kwiatkowski, Piotr,Jurczak, Janusz
-
p. 3869 - 3878
(2007/10/03)
-
- Total syntheses of epothilones B and D
-
A convergent, total synthesis of epothilones B (2) and D (4) is described. The key steps are Normant coupling to establish the desired (Z)-stereochemistry at C12-C13, Wadsworth-Emmons olefination of methyl ketone 28 with the phosphonate ester 8, diastereoselective aldol condensation of aldehyde 5 with the enolate of keto acid derivatives to form the C6-C7 bond, selective deprotection of acid 52, and macrolactonization.
- Jung, Jae-Chul,Kache, Rajashaker,Vines, Kimberly K.,Zheng, Yan-Song,Bijoy, Panicker,Valluri, Muralikrishna,Avery, Mitchell A.
-
p. 9269 - 9284
(2007/10/03)
-
- Enzymatic kinetic resolution of 1-(3′-furyl)-3-buten-1-ol and 2-(2′-furyl)-propan-1-ol
-
The enzymatic kinetic resolution of the racemic alcohols 1-(3′-furyl)-3-buten-1-ol (±)-1 and 2-(2′-furyl)propan-1-ol (±)-2 was investigated by screening a range of lipases and esterases for enantioselective transacylation, as well as for enantioselective hydrolysis. For both alcohols, lipase-catalyzed hydrolysis of the derived racemic acetate gave the best results for accessing the desired (S)-enantiomers. In the case of the secondary alcohol (±)-1, ASL turned out to be the optimum enzyme, whereas PPL was found to be superior in the case of the primary alcohol (±)-2. Additionally, an alternative access to (S)-2 via Oppolzer's camphor sultam methodology is described.
- Bierstedt, Anja,Stoelting, Joern,Froehlich, Roland,Metz, Peter
-
p. 3399 - 3407
(2007/10/03)
-
- Diastereoselective Titanium Enolate Aldol Reaction for the Total Synthesis of Epothilones
-
(Matrix Presented) The development of a highly diastereoselective addition of the titanium enolate derived from ketone 1 to aldehyde 2 offers an efficient entry to the total synthesis of the epothilone family. The new aldol process is robust and tolerates
- Koch, Guido,Loiseleur, Olivier,Fuentes, Daniel,Jantsch, Andrea,Altmann, Karl-Heinz
-
p. 3811 - 3814
(2007/10/03)
-
- Total synthesis of (+)-phorboxazole A exploiting the Petasis-Ferrier rearrangement
-
A highly convergent, stereocontrolled total synthesis of the potent antiproliferative agent (+)-phorboxazole A (1) has been achieved. Highlights of the synthesis include: modified Petasis-Ferrier rearrangements for assembly of both the C(11 - 15) and C(22-26) cis-tetrahydropyran rings; extension of the Julia olefination to the synthesis of enol ethers; the design, synthesis, and application of a novel bifunctional oxazole linchpin; and Stille coupling of a C(28) trimethyl stannane with a C(29) oxazole triflate. The longest linear sequence leading to (+)-phorboxazole A (1) was 27 steps, with an overall yield of 3%.
- Smith III,Minbiole,Verhoest,Schelhaas
-
p. 10942 - 10953
(2007/10/03)
-
- Camphordisulfonamides: Good chiral ligands for the addition of dialkylzinc to aliphatic aldehydes
-
The preparation of several disulfonamides derived from camphor and their use in the titanium tetraisopropoxide-promoted enantioselective addition of dialkylzinc to aldehydes is described. The enantiomeric ratio is up to 98:2, the best results being obtained for aliphatic aldehydes. Copyright (C) 2000 Elsevier Science Ltd.
- Prieto, Oscar,Ramon, Diego J.,Yus, Miguel
-
p. 1629 - 1644
(2007/10/03)
-
- A practical synthesis of optically active (R)-2-propyloctanoic acid: Therapeutic agent for Alzheimer's disease
-
(R)-2-Propyloctanoic acid has been developed as a novel therapeutic agent for Alzheimer's disease. A large-scale synthesis of this candidate was achieved by using Oppolzer's camphorsultam as a chiral auxiliary under improved conditions. It was essential for the successful synthesis of this compound to utilize a new removal method for the chiral source with a combination of tetrabutylammonium hydroxide and hydrogen peroxide. The present process afforded the desired product in high yield with high optical purity.
- Hasegawa, Tomoyuki,Yamamoto, Hisashi
-
p. 423 - 428
(2007/10/03)
-
- Progress toward the total synthesis of callipeltin A (I): Asymmetric synthesis of (3S,4R)-3,4-dimethylglutamine
-
(equation presented) During the total synthesis of the novel cyclic depsipeptide callipeltin A (1), the unit (3S,4R)-3,4-dimethylglutamine, was successfully synthesized by asymmetric Michael addition and subsequent electrophilic azidation. The key feature of this approach is the generation of three adjacent stereogenic centers using the same camphorsultam chiral auxiliary.
- Liang, Bo,Carroll, Patrick J.,Joullie, Madeleine M.
-
p. 4157 - 4160
(2007/10/03)
-
- Three approaches to the synthesis of L-leucine selectively labelled with carbon-13 or deuterium in either diastereotopic methyl group
-
Three approaches to the synthesis of L-leucine selectively labelled with carbon-13 or deuterium in either diastereotopic methyl group as well as at C-3 and C-4 are described. In all three methods the stereogenic centre at C-2 was created with total stereocontrol via a one-pot, two-enzyme catalysed procedure involving hydrolysis and reductive amination of a 2-keto ester. However, the approaches vary in the synthesis of the isotopically labelled 2-keto esters and in the production of the stereogenic centre at C-4 which was achieved either via alkylation of a propionylated Evans' auxiliary with labelled iodomethane or by the diastereoselective conjugate addition of a labelled organocopper reagent to crotonate tethered to a chiral sultam. The latter approach proved most efficient and using the (1R,2S, 3R)-3-[N-phenylsulfonyl-N-(3,5-dimethyldiphenyl)aminobornan-2-ol ester 27, [5-13C]-L-leucine was prepared with >98% de at C-4 and in 49% overall yield from the first labelled intermediate 28.
- Fletcher, Matthew D.,Harding, John R.,Hughes, Rachael A.,Kelly, Nicholas M.,Schmalz, Holger,Sutherland, Andrew,Willis, Christine L.
-
-
- 1,3-dipolar cycloaddition of C-(2-thiazolyl)nitrones to chiral acrylates. Synthesis of enantiopure α-amino-2-alkylthiazoles and 5-formylpyrrolidin-2-ones
-
The 1,3-dipolar cycloaddition of thiazolyl nitrones with chiral acrylates has been studied. The use of the Oppolzer's camphor sultam as chiral inductor provided isoxazolidines with excellent regio- and diastereoselectivities and goad asymmetric induction. The cycloadducts were converted into homochiral α-amino-2-alkylthiazoles and 5-(2-thiazolyl)-3-hydroxy-2-pyrrolidinones. The latter compounds were precursors of highly functionalized pyrrolidines by the aldehyde unmasking from the thiazole ring and subsequent reactions of the formyl group.
- Tejero, Tomas,Dondoni, Alessandro,Rojo, Isabel,Merchan, Francisco L.,Merino, Pedro
-
p. 3301 - 3318
(2007/10/03)
-
- L-(6,7-dimethoxy-4-coumaryl) alanine: An intrinsic probe for the labelling of peptides
-
The asymmetric synthesis, spectral properties and incorporation into solid phase peptide synthesis are described for L-(6,7-dimethoxy-4-coumaryl)alanine (Dca). Dca has great utility as a specific and highly sensitive intrinsic probe for fluorescence labelling and quantitation of peptides and proteins.
- Bennett, Fiona A.,Barlow, David J.,Dodoo, Alexander N.O.,Hider, Robert C.,Lansley, Alison B.,Lawrence, M. Jayne,Marriott, Christopher,Bansal, Sukhvinder S.
-
p. 7449 - 7452
(2007/10/03)
-
- Sodium percarbonate: A multifunctional reagent for the preparation of optically active 4-hydroxy-Δ2- isoxazolines
-
In this letter we report a general method for the preparation of optically active 4-hydroxy-Δ2-isoxazolines. This one-pot method employs sodium percarbonate for nitrile oxide generation, oxidation of the intermediate boronic ester substituted Δ2-isoxazoline, and cleavage of the chiral auxiliary from the final product.
- Liu, Jinchu,Eddings, Alicia,Wallace, Richard H.
-
p. 6795 - 6798
(2007/10/03)
-
- Asymmetric synthesis of sultams and sulfonamides via diastereoselective reduction of N-sulfonylimines
-
The diastereoselective reduction of both cyclic and acyclic camphor sulfonylimines was investigated. With cyclic camphor sulfonylimines 1, reduction using NaBH4 in methanol afforded the corresponding camphorsultams 2 in 92-95% yield as single d
- Davis, Franklin A.,Zhou, Ping,Chen, Bang-Chi
-
-
- A two-step synthesis of camphosultam
-
Modifications of the known route to camphosultam led to an easy two-step process. The unique intermediate is simply isolated by filtration. The overall yield is 66% on a hundred gram scale.
- Capet,David,Bertin,Hardy
-
p. 3323 - 3327
(2007/10/03)
-
- 12. Complete ?-Facial Stereoselectivity in the TiCl4-Mediated Cycloaddition of Cyclopentadiene to N,N-Fumaroyldi
-
Under the co-operative influence of two prosthetic groups, and independent of the TiCl4 concentration, complete and constant diastereofacial ?-selection was achieved during the cycloaddition of cyclopentadiene to N,N'-fumaroyl-di((-)-1c); reactive conformations are discussed.
- Chapuis, Christian,Rzepecki, Piotr,Bauer, Tomasz,Jurczak, Janusz
-
p. 145 - 150
(2007/10/02)
-
- Enantioselective synthesis of N-Fmoc protected di-tert-butyl 4-phosphonomethyl-L-phenylalanine: A hydrolytically stable analogue of O-phosphotyrosine
-
Fmoc-L-Pmp(tBu)2-OH was prepared with high enantiomeric purity by an asymmetric synthetic pathway, using a camphor sultam as chiral auxiliary.
- Liu,Roques,Garbay-Jaureguiberry
-
p. 647 - 650
(2007/10/02)
-
- Development of Methods for the Synthesis of Chiral, Highly Functionalized 2-Amino-4-Aryl-4H-Pyrans
-
The development of new methods for the asymmetric synthesis of highly functionalized 2-amino-4-aryl-4H-pyrans is described.Two alternative synthetic routes: the 1,4-conjugate addition of chiral β-ketoesters 3 or the N-acetoacetyl sultam 11 to arylidenemal
- Marco, Jose L.,Martin, Nazario,Martinez-Grau, Angeles,Seoane, Carlos,Albert, Armando,Cano, Felix H.
-
p. 3509 - 3528
(2007/10/02)
-
- Asymmetric Alkylation of β-Ketoesters: Synthesis and Michael Additions of a Chiral Sultam-Derived Acetoacetyl Equivalent
-
The synthesis and Michael reaction of the chiral acetoacetyl equivalent 1 with arylidenemalonitriles 3 is reported.
- Martin, Nazario,Martinez-Grau, Angeles,Seoane, Carlos,Marco, Jose L.
-
p. 5627 - 5630
(2007/10/02)
-
- Non-destructive Cleavage of N-Acylsultams Under Neutral Conditions: Preparation of Enantiomerically, Pure Fmoc-Protected α-Amino Acids
-
Heating diastereoisomerically pure N-acylsultams 3 or 4 with allyl alcohol/Ti(OR)4 efficiently yields sultams 1 or 2 and allyl esters 5.Esters 5 are hydrolyzed under nonbasic conditions in the presence of Wilkinson's catalyst to give enantiomerically and diastereoisomerically pure carboxylic acids 7.A series of carbonyl-(Fmoc)-protected amino acids 14 were thus prepared from N-acylsultams 12.
- Oppolzer, Wolfgang,Lienard, Philippe
-
p. 2572 - 2582
(2007/10/02)
-
- Asymmetric silyl nitronate cycloadditions with bornane-10,2-sultam derivatives
-
Asymmetric silyl nitronate cycloadditions with N-acryloyl (2R)-bornane-10,2-sultam, N-acryloyl (2S)-bornane-10,2-sultam, and N-methacryloyl (2R)-bornane-10,2-sultam have been studied. The asymmetric silyl nitronate cycloaddition/elimination methodology pr
- Kim,Lee
-
p. 1359 - 1370
(2007/10/02)
-
- Bornanesultam-directed asymmetric synthesis of crystalline, enantiomerically pure syn aldols
-
N-acylsultams 2 furnish, via aldolization of their enolates 16 with aldehydes, diastereomerically pure, crystalline syn aldols. The absolute configuration of the product is controlled by the choice of the enolate counterion: 16, M = B → 3; 16, M = Li or S
- Oppolzer, Wolfgang,Blagg, Julian,Rodriguez, Inès,Walther, Eric
-
p. 2767 - 2772
(2007/10/02)
-
- FLUORINATED HETEROCYCLES: TARGETS IN THE SEARCH FOR BIOACTIVE COMPOUNDS AND TOOLS FOR THEIR PREPARATION
-
To strategies for the preparation and use of fluorinated heterocycles are discussed: 1.)the building block approach being used mainly for the preparation of target heterocycles with fluorinated substituents, and 2.)the direct fluorination approach in which fluorinated heterocycles are used as tools for the preparation of bioactive compounds.Strategies presented in the building block approach include electrophilic reactions of building blocks derived from trifluoroacetic acid (1), as well as the use of building blocks obtained from trichlorotrifluoroethane (2) and chlorodifluoro acetic acid (3) through organometallic reactions.The preparation and use of N-fluoro sultams 62 and 66 are shown in the direct fluorination approach.Both strategies can be successfully used n the synthesis of bioactive compounds of pharmaceutical and agrochemical interest.
- Differding, E.,Frick, W.,Lang, R. W.,Martin, P.,Schmit, C.,et al.
-
p. 647 - 671
(2007/10/02)
-
- ASYMMETRIC ALKYLATION OF N-ACYLSULTAMS: A GENERAL ROUTE TO ENANTIOMERICALLY PURE, CRYSTALLINE C(α,α)-DISUBSTITUTED CARBOXYLIC ACID DERIVATIVES.
-
Successive treatment of acylsultams 2 with nBuLi or NHMDS and primary alkyl halides, followed by crystallization, gave pure C(α)-alkylation products 4 and, via their non-destructive cleavage, enantiomerically pure alcohols 5 or carboxylic acids 6.
- Oppolzer, Wolfgang,Moretti, Robert,Thomi, Silvia
-
p. 5603 - 5606
(2007/10/02)
-
- Asymmetric Induction on Copper(I) Chloride Catalyzed 1,4-Addition of Alkylmagnesium Chlorides to α,β-Disubstituted (E)-Enoylsultams and Subsequent Protonation
-
Successive treatment of conjugated N-enoylsultams 2 with alkyl Grignard reagents/CuCl and aq.NH4Cl solution generated selectively two stereogenic centers at C(α) and C(β) providing, after flash chromatography and crystallization, acylsultams 5 in high purity.Mild cleavage afforded the recovered sultam auxiliary 1 and enantiomerically pure carboxylic acids 7.
- Oppolzer, Wolfgang,Kingma, Arend J.
-
p. 1337 - 1345
(2007/10/02)
-
- ASYMMETRIC 1,4-ADDITIONS OF GILMAN REAGENTS TO α,β-DISUBSTITUTED (E)-ENOYLSULTAMS / "ENOLATE" PROTONATIONS.
-
Successive treatment of (E)-Cα,Cβ-disubstituted N-enoyl sultams 6 and 13 with organocopper reagents (Me2CuLi, (CH2=CH)2CuLi, Ph2CuLi in the presence of PBu3 or SCN(1-)) and aq.NH4Cl gave products 7 and 14, respectively, with good to excellent stereoface d
- Oppolzer, Wolfgang,Kingma, Arend J.,Poli, Giovanni
-
p. 479 - 488
(2007/10/02)
-
- Methylenecyclopropanes, XI. - Asymmetric Nickel(0)-Catalyzed Cycloadditions of Methylenecyclopropanes with Chiral Derivatives of Acrylic Acid
-
The nickel(0)-catalyzed codimerisation of methylenecyclopropane 1a or 2,2-dimethylmethylenecyclopropane (1b) with the chiral derivatives of acrylic acid 2a-2f leads to the optically active 3-methylenecyclopentanecarboxylic esters 3a, 3c-3f, 4a, and 4c, or amides 3b and 4b in good yields.The diastereomeric excess accesible depends on the steric demand of the chiral auxiliaries, de values up to 98percent can be achieved.Some improvements of the preparation of optically pure auxiliaries are also described.
- Binger, Paul,Brinkmann, Axel,Roefke, Petra,Schaefer, Bernd
-
p. 739 - 750
(2007/10/02)
-
- ENANTIOSELECTIVE SYNTHESIS AND ABSOLUTE CONFIGURATION OF (-)-PULO'UPONE BY ASYMMETRIC INTRAMOLECULAR DIELS-ALDER REACTION
-
(-)-Pulo'upone (1) was synthesized via an asymmetric, bornane-10,2-sultam- directed, intramolecular Diels-Alder reaction (3->2) and a 2-pyridylcuprate/allylacetate coupling (18->1).The (6'R,9'S,13'R,14'R)-configuration of (-)-1 follows from an X-ray diffraction analysis of the cycloaddition product 2.
- Oppolzer, Wolfgang,Dupuis, Dominique,Poli, Giovanni,Raynham,Tony M.,Bernardinelli, Gerald
-
p. 5885 - 5888
(2007/10/02)
-
- The Preparation of Optically Active Δ2-Isoxazolines. A Model for Asymmetric Induction in the Non Lewis Acid Catalyzed Reactions of Oppolzer's Chiral Sultam
-
Good diastereoselectivity (ca. 90/10) is reported in the cycloaddition reactions of Oppolzer's chiral sultam with nitrile oxides.A model is proposed which may apply to other non Lewis acid promoted reactions of this sultam.
- Curran, Dennis P.,Kim, Byeang Hyean,Daugherty, James,Heffner, Timothy, A.
-
p. 3555 - 3558
(2007/10/02)
-
- NEW FLUORINATING REAGENTS - I. THE FIRST ENANTIOSELECTIVE FLUORINATION REACTION
-
Crystalline, optically pure N-fluoro sultams (-)-3 and (+)-5 are the first examples of enantioselective fluorinating reagents.Thus unprecedented enantiomeric excesses up to 70 percent are observed when various prochiral metal enolates are fluorinated by u
- Differding, Edmond,Lang, Robert W.
-
p. 6087 - 6090
(2007/10/02)
-
- Asymmetric Dihydroxylations of β-Substituted N-(α,β-Enolyl)bornane-10,2-sultams
-
Pure (E)- or (Z)-enoylsultams 2 were oxidized with OsO4/N-methylmorpholine N-oxide in a stereospecific and highly ?-face selective manner.Acetalization of the resulting 1,2-diols furnished, after purification, the stable, crystalline acetals 6 in >99percent d.e. and in 63-74percent overall yield from 2.Reductive or hydrolytic cleavage of 6 gave enantiometrically pure alcohols 8 or carboxylic acids 9 with recovery of the sultam auxiliary 1.
- Oppolzer, Wolfgang,Barras, Jean-Pierre
-
p. 1666 - 1675
(2007/10/02)
-
- ASYMMETRIC INDUCTION AT C(β) AND C(α) OF N-ENOYL SULTAMS BY 1,4-HYDRIDE ADDITION/ENOLATE TRAPPING
-
Conjugate addition of L-Selectride to α,β-enoyl sultams 1 and 4 followed by electrophilic trapping of the resulting enolates gave in one operation saturated imides with high β- and/or α- stereodifferentiation.
- Oppolzer, Wolfgang,Poli, Giovanni
-
p. 4717 - 4720
(2007/10/02)
-
- ASYMMETRIC INTRAMOLECULAR DIELS-ALDER REACTIONS OF N-ACYL-CAMPHOR-SULTAM TRIENES.
-
Treatment of triene-imides 4 with EtAlCl2 at -20 deg C gave crystalline cycloadducts 5 which furnished enantiomerically pure bicyclic alcohols 9 with regeneration of the chiral auxilary.
- Oppolzer, Wolfgang,Dupuis, Dominique
-
p. 5437 - 5440
(2007/10/02)
-
- Camphor-Derived N-Acryloyl and N-Crotonoyl Sultams: Practical Activated Dienophiles in Asymmetric Diels-Alder Reactions
-
Starting from (+)-camphor-10-sulfonyl chloride (5), the crystalline sultam 8 was easily prepared.Lewis-acid-promoted Diels-Alder additions of the crystalline N-acryloyl and N-crotonoyl derivatives 9 and 10, respectively, to cyclopentadiene and 1,3-butadiene at -130 to -78 grad furnished adducts 11, 12 and 17 with high chiral efficiency.Crystallization of the adducts and nondestructive removal of 8 gave either alcohols 13, 14 and 18 or acid 19 in 99percent enantiomeric purity.The sense of induction was reversed on using the enantiomer of 8 as the auxiliary.The structure of 10 was established by X-ray diffraction analysis
- Oppolzer, Wolfgang,Chapuis, Christian,Bernardinelli, Gerald
-
p. 1397 - 1401
(2007/10/02)
-