- Controlled Reduction of Nitriles by Sodium Hydride and Zinc Chloride
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A new protocol for the controlled reduction of nitriles to aldehydes was developed using a combination of sodium hydride and zinc chloride. The iminyl zinc intermediates derived from aromatic nitriles could be further functionalized with allylmetal nucleophiles to afford homoallylamines. As the method allows the reduction of various aliphatic and aromatic nitriles with a concise procedure under milder reaction conditions and exhibits wide functional group compatibility, it is well suited for use in various opportunities in chemical synthesis.
- Chiba, Shunsuke,Ong, Derek Yiren
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p. 1369 - 1378
(2020/04/27)
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- SUBSTITUTED HETEROARYL COMPOUNDS AND METHODS OF USE
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The present invention provides novel heteroaryl compounds, pharmaceutical acceptable salts and formulations thereof. They are useful in preventing, managing, treating or lessening the severity of a protein kinase-mediated disease. The invention also provides pharmaceutically acceptable compositions comprising such compounds and methods of using the compositions in the treatment of protein kinase-mediated disease.
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- Substituted heteroaryl compound and composition thereof, and uses of substituted heteroaryl compound and composition thereof
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The present invention provides a substituted heteroaryl compound and a composition thereof, and uses of the substituted heteroaryl compound and the composition, wherein the compound is a compound represented by a formula (I) or a stereoisomer, a tautomer, a nitrogen oxide, a solvate, a metabolite, a pharmaceutically acceptable salt or a prodrug of the compound represented by the formula (I). The present invention further provides a pharmaceutical composition containing the compound, wherein the pharmaceutical composition can regulate activity of protein kinases, particularly Aurora kinases and JAK kinases, and can be used for prevention, treatment, therapy and alleviation of protein kinases, particularly Aurora kinases and JAK kinase activity mediated diseases or disorders.
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- Ynamide Carbopalladation: A Flexible Route to Mono-, Bi- and Tricyclic Azacycles
-
Bromoenynamides represent precursors to a diversity of azacycles by a cascade sequence of carbopalladation followed by cross-coupling/electrocyclization, or reduction processes. Full details of our investigations into intramolecular ynamide carbopalladation are disclosed, which include the first examples of carbopalladation/cross-coupling reactions using potassium organotrifluoroborate salts; and an understanding of factors influencing the success of these processes, including ring size, and the nature of the coupling partner. Additional mechanistic observations are reported, such as the isolation of triene intermediates for electrocyclization. A variety of hetero-Diels-Alder reactions using the product heterocycles are also described, which provide insight into Diels-Alder regioselectivity.
- Campbell, Craig D.,Greenaway, Rebecca L.,Holton, Oliver T.,Walker, P. Ross,Chapman, Helen A.,Russell, C. Adam,Carr, Greg,Thomson, Amber L.,Anderson, Edward A.
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supporting information
p. 12627 - 12639
(2015/09/01)
-
- A formal synthesis of herboxidiene/GEX1A
-
A formal synthesis of herboxidiene/GEX 1A is described. This approach demonstrates successful application of the Prins cyclization for the construction of the tetrahydropyran core of the target molecule. The chirality of the side chain has been established through the Sharpless asymmetric dihydroxylation and Evan's alkylation. The olefin cross-metathesis was applied to couple both key fragments. Copyright
- Yadav, Jhillu S.,Reddy, G. Madhusudhan,Anjum, S. Rehana,Reddy, B. V. Subba
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p. 4389 - 4397
(2014/07/21)
-
- Palladium on charcoal as a catalyst for stoichiometric chemo- and stereoselective hydrosilylations and hydrogenations with triethylsilane
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Stoichiometric quantities of triethylsilane in the presence of activated Pd/C as the catalyst can be used to effect chemo-, regio-, and stereoselective hydrosilylation and transfer hydrogenation reactions. α,β-Unsaturated aldehydes and ketones are selectively hydrosilylated to give the corresponding enol silanes or transfer hydrogenated to give the saturated carbonyl compounds in the presence of other reducible functional groups.
- Tuokko, Sakari,Pihko, Petri M.
-
p. 1740 - 1751
(2015/02/19)
-
- DIHYDROPYRONE COMPOUNDS AND HERBICIDES COMPRISING THE SAME
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The present invention provides a compound having an excellent efficacy for controlling weeds. A dihydropyrone compound of formula (I): wherein m is 1, 2 or 3; n is an integer of any one of 1 to 5; X represents O, S, S(O) or S(O)2; R1 /sup
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-
- Tethered aminohydroxylation: Synthesis of the β-amino acid of microsclerodermins A and B
-
The utility of the tethered aminohydroxylation (TA) has been demonstrated by synthesis of the complex β-amino acid residue of microsclerodermins A and B. The TA provided a regio- and stereoselective functionalization of a complex homoallylic alcohol. The route includes late-stage introduction of the aliphatic side chain via a cuprate addition and cross metathesis, a tactic designed to render the synthesis applicable to other microsclerodermins.
- Pullin, Robert D. C.,Rathi, Akshat H.,Melikhova, Ekaterina Y.,Winter, Christian,Thompson, Amber L.,Donohoe, Timothy J.
-
supporting information
p. 5492 - 5495
(2013/11/19)
-
- Synthesis of the gymnodimine tetrahydrofuran core through a Ueno-Stork radical cyclization
-
A straightforward access to the C10-C20 skeleton of gymnodimine, incorporating a tetrahydrofuran fragment, is described. The elaboration of the THF moiety is based on a stereocontrolled Ueno-Stork cyclization. A Lewis-acid mediated allylation of the resulting acetal at C13 and a Horner-Wadsworth-Emmons olefination on the ketone at C17 complete the synthesis.
- Toumieux, Sylvestre,Beniazza, Redouane,Desvergnes, Valerie,Araoz, Romulo,Molgo, Jordi,Landais, Yannick
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supporting information; experimental part
p. 3726 - 3732
(2011/06/27)
-
- Palladium-catalyzed cascade cyclization of ynamides to azabicycles
-
Cascade reactions: A modular assembly of azabicycles by using a cascade cyclization/Suzuki coupling/6π-electrocyclization of bromoenynamides is reported (see scheme). The reaction offers a wide substituent scope on the bicyclic aminodiene products, which can be selectively oxidized as a general approach to aromatic azabicycles.
- Greenaway, Rebecca L.,Campbell, Craig D.,Holton, Oliver T.,Russell, C. Adam,Anderson, Edward A.
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supporting information; scheme or table
p. 14366 - 14370
(2012/02/04)
-
- Stereoselective synthesis of the C15-C26 fragment of the antitumor agent (-)-dictyostatin
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The synthesis of the C15-C26 fragment of (-)-dictyostatin is reported in 10 steps and 28% overall yield. The key steps are the two stereoselective sulfoxide-directed processes: a Reformatsky-type reaction and a β-keto sulfoxide reduction.
- Ferreiro-Mederos, Leticia,Vila-Gisbert, Silvia,Urbano, Antonio,Carreno, M. Carmen,Colobert, Franoise
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p. 758 - 764
(2011/04/16)
-
- Solvent-free olefin hydroformylation using hemispherical diphosphites
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With rhodium complexes containing hemispherical diphosphite ligands derived from a calixarene skeleton, olefins can be hydroformylated efficiently under solvent-free conditions. For example, in the hydroformylation of 1-octene (T = 80 °C, P = 20 bar, olefin:Rh = 200 000:1) one of the catalysts investigated resulted in a TOP of 17290 mol (converted 1-octene)mol(Rh)-1h -1, the regioselectivity towards the linear aldehyde reaching then 97.9%.
- Monnereau, Laure,Semeril, David,Matt, Dominique
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experimental part
p. 3068 - 3073
(2010/08/07)
-
- COMPOUNDS FOR THE TREATMENT OF METABOLIC DISORDERS
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The present invention is directed to therapeutic compotmds of the following formula (I) which have activity as agonists of GPR 119 and are useful for the treatment of metabolic disorders including type II diabetes.
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-
Page/Page column 28
(2010/10/03)
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- Total synthesis of emericellamide A: A secondary metabolite of marine cyclic depsipeptide with antimicrobial properties
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Emericellamide A is a secondary metabolite of marine cyclic depsipeptide from the co-culture of the marine-derived fungus Emericella sp. and actinomycete Salinispora arenicola. A general method for the total synthesis of emericellamide A is depicted in th
- Ma, Jing-Yi,Xu, Long-Fei,Huang, Wen-Feng,Wei, Bang-Guo,Lin, Guo-Qiang
-
scheme or table
p. 1307 - 1310
(2009/11/30)
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- Highly regioselective hydroformylation with hemispherical chelators
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The hemispherical diphosphites (R,R)- or (S,S)-5,11,17,23-tetratert-butyl- 25,27-di(OR)-26,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy) -calix[4]arene (R = OPr, OCH2Ph, OCH2-naphtyl, O-fluorenyl; R = H, R' = OPr) (LR), all with C2 symmetry, have been synthesised starting from the appropriate di-O-alkylated calix[4]-arene precursor. In the presence of [Rh(acac)(CO)2], these ligands straightforwardly provide chelate complexes in which the metal centre sits in a molecular pocket defined by two naphthyl planes related by the C 2 axis and the two apically situated R groups. Hydroformylation of octene with the LPr/Rh system turned out to be highly regioselective, the linear-to-branched (l:b) aldehyde ratio reaching 58:1. The l:b ratio significantly increased when the propyl groups were replaced by -CH 2Ph (l:b = 80) or -CH2naphthyl (1:b = 100) groups, that is, with substituents able to sterically interact with the apical metal sites, but without inducing an opening of the cleft nesting the catalytic centre. The trend to preferentially form the aldehyde the shape of which fits with the shape of the catalytic pocket was further confirmed in the hydroformylation of styrene, for which, in contrast to catalysis with conventional diphosphanes, the linear aldehyde was the major product (up to ca. 75 % linear aldehyde). In the hydroformylation of frarts-2-octene with the Lbenzyl/ Rh system, combined isomerisation/hydroformylation led to a remarkably high 1:b aldehyde ratios of 25, thus showing that isomerisation is more effective than hydroformylation. Unusually large amounts of linear products were also observed with all the above diphosphites in the tandem hydroformylation/amination of styrene (1:b of ca. 3:1) as well as in the hydroformylation of allyl benzyl ether (1:b ratio up to 20).
- Semeril, David,Matt, Dominique,Toupet, Loic
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experimental part
p. 7144 - 7155
(2009/08/07)
-
- Total synthesis of epothilones B and D: Stannane equivalents for β-keto ester dianions
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(Chemical Equation Presented) Studies leading to a total synthesis of epothilones B and D are described. The overall synthetic plan was based on late-stage fragment assembly of two segments representing C1-C 9 and C10-C21 of the structure. The C 1-C9 fragment was prepared by elaboration of commercially available (2R)-3-hydroxy-2-methylpropanoate at both ends of the three-carbon unit. Introduction of carbons 1-4 containing the gem-dimethyl unit was achieved in a convergent manner using a diastereoselective addition of a stannane equivalent of a β-keto ester dianion. An enantioselective addition of such a stannane equivalent for a β-keto ester dianion was also used to fashion one version of the C10-C21 subunit; however, the fragment assembly (using bimolecular esterification followed by ring-closing metathesis) with this subunit failed. Therefore, fragment assembly was achieved using a Wittig reaction; this was followed by macrolactonization to close the macrocycle. The C10-C21 subunit needed for this approach was prepared in an efficient manner using the Corey-Kim reaction as a key element. Other key reactions in the synthesis include a stereoselective SmI 2 reduction of a β-hydroxy ketone and a critical opening of a valerolactone with aniline which required extensive investigation.
- Keck, Gary E.,Giles, Robert L.,Cee, Victor J.,Wager, Carrie A.,Yu, Tao,Kraft, Matthew B.
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supporting information; experimental part
p. 9675 - 9691
(2009/04/07)
-
- PIPERIDINES AND RELATED COMPOUNDS FOR TREATMENT OF ALZHEIMER’S DISEASE
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Compounds of formula (I) are modulators of gamma-secretase, and hence are useful in treatment of Alzheimer’s disease.
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-
- Studies directed towards the synthesis of botcinolides: synthesis of the nonalactone ring of 2-epibotcinolide
-
Synthesis of the polyoxygenated nonalactone ring of 2-epibotcinolide was achieved using a highly stereoselective aldol reaction of the titanium enolate from a lactate-derived chiral ketone, a stereoselective dihydroxylation and a Yamaguchi macrolactonizat
- Chakraborty, Tushar Kanti,Goswami, Rajib Kumar
-
p. 4917 - 4919
(2007/10/03)
-
- The first stereoselective total synthesis of lankanolide. Part 2
-
The seco-acid derivative designed by conformation calculation and lactonization experiment of model seco-acids was synthesized, and subjected to macrolactonization to afford the lactone derivative. The lankanolide was synthesized via several steps after the lactonization, and the synthetic lankanolide was confirmed to have the same physical data (NMR, mass, IR and αD) as the lankanolide prepared from lankamycin according to the reported method.
- Hamada, Tatsuo,Kobayashi, Yukinari
-
p. 4347 - 4350
(2007/10/03)
-
- Stereoselective synthesis of (2R,3R,4R)-3-hydroxy-2,4,6-trimethylheptanoic acid and determination of the absolute stereochemistry of the natural product from callipeltin A
-
A revised stereostructure of 3-hydroxy-2,4,6-trimethylheptanoic acid, the β-hydroxy acid that acylates the N-terminus of callipeltin A, is proposed on the basis of analysis of J-coupling in the 1H NMR spectrum of the acetonide derivative obtain
- Zampella, Angela,D'Auria, Maria Valeria
-
p. 1237 - 1239
(2007/10/03)
-
- Synthetic studies on callipeltin A: Stereoselective synthesis of (2R,3R,4S)-3-hydroxy-2,4,6-trimethylheptanoic acid
-
An efficient and highly stereocontrolled synthesis of protected (2R,3R,4S)-3-hydroxy-2,4,6-trimethylheptanoic acid, the β-hydroxy acid unit that acylates the N-terminus of callipeltin A, has been devised starting from methyl (2S)-2-methyl-3-hydroxypropion
- Zampella, Angela,Sorgente, Maria,D'Auria, Maria Valeria
-
p. 681 - 685
(2007/10/03)
-
- 6-AZAINDOLE COMPOUNDS AS ANTAGONISTS OF GONADOTROPIN RELEASING HORMONE
-
There are disclosed compounds of formula (I) and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and women.
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-
- Chemoenzymatic Approach toward the Pure Enantiomers of 2-Methyl-1,3-propanediol Mono(p-Methoxybenzyl Ether)
-
In a route towards the enantiomerically pure 2-methylpropane-1,3-diol mono(p-methoxybenzyl ether), which is an important starting material for natural product synthesis, a kinetic resolution approach by means of lipase-catalyzed hydrolysis as well as acyl
- Akeboshi, Tomohiro,Ohtsuka, Yoshikazu,Ishihara, Takashi,Sugai, Takeshi
-
p. 624 - 637
(2007/10/03)
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- ANTAGONISTS OF GONADOTROPIN RELEASING HORMONE
-
There are disclosed compounds of formula (I) STR1 and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and women.
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-
- Antagonists of gonadotropin releasing hormone
-
There are disclosed compounds of formula (I) STR1 and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and women.
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-
- Antagonists of gonadotropin releasing hormone
-
There are disclosed compounds of formula (I) and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and women.
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-
- Synthesis of the C1-C13 fragment of leucascandrolide A.
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[reaction: see text] The synthesis of the C1-C13 fragment 3 of leucascandrolide A has been completed utilizing a stereoselective and regioselective reductive cleavage of a highly functionalized spiroketal to incorporate the cis-2,6-disubstituted tetrahydropyan. The spiroketal was constructed by addition of a lithiated pyrone 5 to aldehyde 6.
- Crimmins,Carroll,King
-
p. 597 - 599
(2007/10/03)
-
- ANTAGONISTS OF GONADOTROPIN RELEASING HORMONE
-
There are disclosed compounds of formula (I) STR1 and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and wo
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-
-
- ANTAGONISTS OF GONADOTROPIN RELEASING HORMONE
-
There are disclosed compounds of formula (I) STR1 and pharmaceutically acceptable salts thereof which are useful as antagonists of GnRH and as such may be useful for the treatment of a variety of sex-hormone related and other conditions in both men and women.
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-
- Palladium(II)-catalyzed oxidation of alcohols to aldehydes and ketones by molecular oxygen
-
A novel combination of Pd(OAc)2/pyridine/MS3A catalyzes the aerobic oxidation in toluene of a variety of primary and secondary alcohols into the corresponding aldehydes and ketones in high yields. Various substituents and protecting groups are compatible with this oxidation. The ca. 2:3 ratio of O2 uptake to product yield is observed, whereas in the absence of MS3A, the ratio is ca. 1:1, suggesting the in situ formation of H2O2 and its decomposition by MS3A into water and oxygen. A catalytic cycle including the formation of a Pd(II)-alcoholate followed by β-elimination of a Pd(II)H species and a carbonyl compound and then the formation of a Pd(II)OOH species is proposed.
- Nishimura, Takahiro,Onoue, Tomoaki,Ohe, Kouichi,Uemura, Sakae
-
p. 6750 - 6755
(2007/10/03)
-
- The total synthesis of scytophycin C. Part 1: Stereocontrolled synthesis of the C1-C32 protected seco acid
-
A stereocontrolled synthesis of the C1-C32 seco acid derivative 9 for scytophycin C (1) was completed in 14 steps (18.2% yield, 85% ds) from aldehyde (S)-18. Key steps include: (i) the asymmetric crotylboration of (S)- 18 to give hom
- Paterson, Ian,Yeung, Kap-Sun,Watson, Christine,Ward, Richard A.,Wallace, Paul A.
-
p. 11935 - 11954
(2007/10/03)
-
- Improved Synthesis of the C8-C23 Segment of Aplysiatoxins via Asymmetric Dihydroxylation of the Chiral Homoallylic Alcohol
-
Important intermediate 2 of the segment (3) possessing four sequential asymmetric centers (C9-C12) of aplysiatoxins was synthesized via dihydroxylation of 5 in only 7 steps from methyl (S)-3-hydroxy-2-methylpropionate.Another promising compound (10a) was
- Toshima, Hiroaki,Ichihara, Akitami
-
p. 599 - 602
(2007/10/03)
-
- Synthesis of the acyltetronic acid ionophore tetronasin (ICI M139603)
-
A synthetic strategy for the preparation of tetronasin 1, an acyltetronic acid ionophore demonstrating antibiotic, antiparasitic and growth promotion in ruminants is described. The key step involves a metal mediated cyclization reaction which creates two
- Ley, Steven V.,Brown, Dearg S.,Clase, J. Andrew,Fairbanks, Antony J.,Lennon, Ian C.,Osborn, Helen M. I.,Stokes, Elaine S. E.,Wadsworth, David J.
-
p. 2259 - 2276
(2007/10/03)
-
- Highly Diastereoselective Cycloadditions via Chelation Control: Asymmetric Synthesis of β-Lactones
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Chelation controlled cycloadditions of trimethylsilylketene to chiral α- and β-benzyloxyaldehydes followed by desilylation provides a highly diastereoselective route to functionalized β-lactones.Several Lewis acids were examined and MgBr2*Et2O was found to give the highest diastereoselectivities and yields.
- Zemribo, Ronald,Romo, Daniel
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p. 4159 - 4162
(2007/10/02)
-
- Palladium(II)-Catalyzed Asymmetric Acetalization of Alkenes
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The terminal olefinic carbon of N-methaacryloyl-2-oxazolidinones is smoothly acetalized by alcohols in the presence of PdCl2 catalyst.The use of 4(S)-isopropyl-, phenyl-, and tert-butyl-2-oxazolidinones as the chiral auxiliary resulted in the formation of the corresponding (2'S)-acetals in 61, 80, and 95percent de, respectively.Reductive removal of the auxiliary with LiAlH4 followed by deacetalization produced (R)-3-hydroxy-2-methylpropanal.The enantiomer of this compound, derived from 4(R)-substituted oxazolidinones, served as a building block for synthesizing a 1β-methylcarbapenem precursor in high enantiomeric excess.In the acetalization of 3',3'-dideuteriated methacryloyl-4-isopropyloxazolidinone with MeOH, one D-atom on the terminal olefinic carbon stereoselectively migrated to the chiral center in the product acetal.On the basis of this 1,2-hydride migration and the conformational preference of the methacryloyl moiety, the reaction pathway and the mechanism of the diastereoselection are discussed.
- Hosokawa, Takahiro,Yamanaka, Toshio,Itotani, Motohiro,Murahashi, Shun-Ichi
-
p. 6159 - 6167
(2007/10/03)
-
- SN2'-Reactions of Peptide Aziridines. A Cuprate-Based Approach to (E)-Alkene Isosteres
-
Alkenylaziridines were prepared from allylic alcohols via Sharpless epoxidation, oxirane to aziridine conversion under modified Staudinger conditions, and Wittig chain extension.Alternatively, β-hydroxy α-amino acids such as threonine can serve as readily
- Wipf, Peter,Fritch, Paul C.
-
p. 4875 - 4886
(2007/10/02)
-
- 1,5-Asymmetric Induction in Lewis Acid-promoted Reactions of (5-Alkoxy-2,4-dimethylpent-2-enyl)tributylstannanes and Aldehydes
-
Allyltin trihalides generated in situ from (5-alkoxy-2,4-dimethylpent-2-enyl)tributylstannanes 8-10 and tin(IV) halides react with aldehydes with excellent 1,5-stereocontrol.
- Teerawutgulrag, Aphiwat,Thomas, Eric J.
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p. 2863 - 2864
(2007/10/02)
-
- Pheromone Synthesis, CXXXV. Synthesis of (4R,5R,6S,7E,9E)-4,6,8-Trimethyl-7,9-undecadien-5-ol and Its Antipode, the Female Specific Compound of the Woodroach Cryptocercus punctulatus
-
(4R,5R,6S,7E,9E)-4,6,8-Trimethyl-7,9-undecadien-5-ol (1) and its antipode 1', the female specific compound of the woodroach Cryptocercus punctulatus, were synthesized by starting from methyl (R)-3-hydroxy-2-methylpropanoate (C). Key Words: Chiral centers,
- Mori, Kenji,Itou, Masamichi
-
-
- Super-acid Catalysed Addition of Allylsilanes to Carbonyl Compounds; Synthetic and Mechanistic Aspects
-
The addition of allyltrimethylsilane 8 to a variety of aldehydes and one ketone (cyclohexanone) was found to be induced by the super-acid TfOH2(1+)B(OTf)4(1-) (Tf = CF3SO2).In contrast to the analogous Lewis acid catalysed reaction, only catalytic amounts
- Davis, Anthony P.,Jaspars, Marcel
-
p. 2111 - 2118
(2007/10/02)
-
- NOREPHEDRINE DERIVED 2-METHOXY OXAZOLIDINES AS CHIRAL FORMYL CATION EQUIVALENTS
-
Lewis acid catalyzed reaction of silylenolethers with 1 followed by a straightforward nondestructive removal of the chiral auxiliary affords the corresponding aldehydes in good e.e.Compound 1 respresents the first effective synthetic equivalent of formyl cation.
- Bernardi, Anna,Cardani, Silvia,Carugo, Oliviero,Colombo, Lino,Scolastico, Carlo,Villa, Roberto
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p. 2779 - 2782
(2007/10/02)
-
- Total synthesis of N-phthaloyl adda methyl ester: All stereocenters originating from a single chiral epoxyalcohol
-
Selective ring opening of (2S,3R)-epoxide of 4-benzyloxy-cis-2-buten-1-ol either at 2- or 3-position ensures stereospecific construction of all the chiral centers of Adda.
- Chakraborty,Joshi
-
p. 2043 - 2046
(2007/10/02)
-
- THE ABSOLUTE CONFIGURATIONS AT 8 And 9-CARBONS OF ADDA, AN AMINO ACID COMPONENT OF A HEPATOTOXIN, CYANOVIRIDIN RR
-
The absolute configurations at 8 and 9-positions of Adda (2), a component of cyanoviridin RR isolated from Microcystis species (Cyanobacteria), have been synthetically determined as S, S.
- Tsukuda, Takuo,Kakisawa, Hiroshi,Painuly, Praba,Shimizu, Yuzuru
-
p. 4245 - 4248
(2007/10/02)
-
- ALDOL CONDENSATIONS OF CHIRAL ETHYLKETONES: CONTROL BY CHIRAL BORON REAGENTS.
-
The chiral reagents (+)- and (-)-(Ipc)2BOTf, in the presence of Et3N, are used to control the aldol condensation reactions of chiral ethylketone 5 with prochiral aldehydes.The SS isomer, 6 or 8, or SA isomer, 7 or 9, is then formed in >99 percentee and wi
- Paterson, Ian,Lister, Anne M.
-
p. 585 - 588
(2007/10/02)
-
- A NOVEL, DOUBLE-ASYMMETRIC ALDOL APPROACH TO THE SYNTHESIS OF A 1β-METHYL CARBAPENEM ANTIBIOTIC PRECURSOR
-
A novel synthetic approach to the 1β-methyl carbapenem key precursor is described which involves the chelation-controlled double-asymmetric aldol reaction as the key step.
- Shirai, Fumiyuki,Nakai, Takeshi
-
p. 6461 - 6464
(2007/10/02)
-
- Stereochemistry of SN2' Additions to Acyclic Vinyloxiranes
-
The isomeric trans-(E)-, trans-(Z)-, cis-(E)-, and cis-(Z)-vinyloxiranes 7,9,17 and 19 were prepared from 2-(benzyloxy)ethanol by sequential Swern-Wittig or Swern-Horner-Emmons propionate condensation, DIBAH reduction, Sharpless epoxidation, Swern oxidation, Wittig or Horner-Emmons acetate condensation, and a second DIBAH reduction.Addition of lithium dimethylcuprate and lithium methylcyanocuprate to these epoxides in THF-eather at -20 to 0 deg C afforded the allylic alcohols 22,25, ent-23, and ent-22 as the major products.These products are formed by anti addition to the lower energy conformer (s-trans for 7,17, and 19 and s-cis for 9) of the respective vinyloxirane.The conformational preferences of transition-state-like geometries of the vinyl-oxiranes, calculated with the aid of Still's MACROMODEL program, were in agreement with the observed trends.
- Marshall, James A.,Trometer, Joseph D.,Blough, Bruce E.,Crute, Thomas D.
-
p. 4274 - 4282
(2007/10/02)
-
- Chelation-Controlled Enantioselective Synthesis of Key Intermediates for the Preparation of Carbapenem Antibiotics PS-5 and 1β-Methyl-PS-5
-
Reaction of the E silyl ketene acetal derived from (1S,2R)-N-methylephedrine butyrate (7) with TiCl4 and β-alkoxy aldehyde 5 gave the aldol product in 75percent yield as a 78:11:11 mixture of stereoisomers.In agreement with a chelated transition structure
- Gennari, Cesare,Cozzi, Pier Giorgio
-
p. 4015 - 4021
(2007/10/02)
-