- Cu-catalyzed enantioselective conjugate additions of alkyl zinc reagents to unsaturated N-acyloxazolidinones promoted by a chiral triamide phosphane
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A chiral triamide phosphane promotes highly efficient and enantioselective Cu-catalyzed conjugate additions of alkyl zinc compounds to unsaturated oxazolidinones (see scheme). The resulting β-alkyl chiral oxazolidinones are readily converted into synthetically useful carbonyl compounds not accessible by alternative catalytic methods.
- Hird, Alexander W.,Hoveyda, Amir H.
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- Asymmetric hydrogenation of prochiral carboxylic acids catalyzed by the five-coordinate ruthenium(II)-hydride complex PF6 (binap = (R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl)
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The five-coordinate complex PF6 (1, binap = (R)- or (S)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) has been found to have sufficient catalytic activity for asymmetric hydrogenation of itaconic acid and other prochiral carboxylic acids under mild conditions.The catalytic hydrogenation of itaconic acid by I was examined under a variety of conditions, and the addition of triethylamine was found to effect high enantioselectivities (above 90percent ee). 1H and 31 P NMR examinations of reaction mixtures of I and itaconic acid under conditions similar to the hydrogenation suggested the formation of ruthenium species containing one binap chelate.
- Saburi, Masahiko,Takeuchi, Hiroshi,Ogasawara, Masamichi,Tsukahara, Touru,Ishii, Youichi,et al.
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- A Concise Synthesis of (-)-Dihydroprotolichesterinic Acid via Consecutive Stereocontrolled 1,4-Conjugate Addition and syn-Aldol Condensation Reactions
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(-)-Dihydroprotolichesterinic acid 1a is synthesised in 6 steps and 57percent overall yield by a strategy employing the camphene-derived chiral auxiliary 2 to construct the three contiguous stereogenic centres in consecutive stereocontrolled 1,4-conjugate addition and syn-aldol reactions.
- Banks, Malcolm R.,Dawson, Ian M.,Gosney, Ian,Hodgson, Philip K. G.,Thorburn, Paul
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- Characterization of chlorinated valepotriates from Valeriana jatamansi
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HPLC-PDA-MS and TLC analysis were used to look for minor cytotoxic chlorinated valepotriates from whole plants of Valeriana jatamansi (syn. Valeriana wallichii DC.). This resulted in isolation of 15 chlorinated valepotriates, designated as chlorovaltrates A-O, together with six known analogues, (1S,3R,5R,7S,8S,9S)-3,8-epoxy-1,5-dihydroxyvalechlorine, volvaltrate B, chlorovaltrate, rupesin B, (1S,3R,5R,7S,8S,9S)-3,8-epoxy-1-O-ethyl-5- hydroxyvalechlorine, and (1R,3R,5R,7S,8S,9S)-3,8-epoxy-1-O-ethyl-5- hydroxyvalechlorine. Their structures were elucidated by spectroscopic methods including homo- and heteronuclear two-dimensional NMR experiments. Chlorovaltrates K-N, chlorovaltrate and rupesin B showed moderate cytotoxicity against lung adenocarcinoma (A 549), metastatic prostate cancer (PC-3M), colon cancer (HCT-8) and hepatoma (Bel 7402) cell lines with IC50 values of 0.89-9.76 μM.
- Lin, Sheng,Zhang, Zhong-Xiao,Chen, Tao,Ye, Ji,Dai, Wei-Xing,Shan, Lei,Su, Juan,Shen, Yun-Heng,Li, Hui-Liang,Liu, Run-Hui,Xu, Xi-Ke,Wang, Hui,Zhang, Wei-Dong
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- Novel iridium complex of spirophosphine-carboxylic acid, preparation method and application thereof
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The invention relates to an iridium complex of spirophosphine-carboxylic acid, a preparation method and application thereof. The iridium complex of spirophosphine-carboxylic acid is a compound with a structure shown as formula (I), wherein n=0-3; and the values of R1, R2, R3, R4, R5, R6 and R7 are defined as claim 1. Substituted 7-carboxyl-7'-diarylphosphino-1, 1'-spirobiindane is taken as the ligand to from carboxylic acid anion under the action of alkali, and then complexation with an iridium precursor is carried out to obtain different iridium/spirophosphine-carboxylic acid complexes. The iridium complex of spirophosphine-carboxylic acid provided by the invention can catalyze the asymmetric hydrogenation reaction of a variety of unsaturated carboxylic acids, and show high activity and enantioselectivity, thus having good industrialization prospects. (formula (I)).
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Paragraph 0076; 0077; 0079
(2017/05/20)
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- Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids
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We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF?) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.
- Yang, Shuang,Che, Wen,Wu, Hui-Ling,Zhu, Shou-Fei,Zhou, Qi-Lin
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p. 1977 - 1980
(2017/03/09)
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- Copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to α′-oxy enones
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The copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to α'-oxy enones was investigated. Cu(OTf)2, ligand, and toluene were placed in a flame-dried Schlenk tube. the resulting mixture was stirred at room temperature f
- Garcia, Jesus M.,Gonzalez, Alberto,Kardak, Bharat G.,Odriozola, Jose M.,Oiarbide, Mikel,Razkin, Jesus,Palomo, Claudio
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supporting information; experimental part
p. 8768 - 8771
(2009/10/01)
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- Highly enantioselective copper-phosphoramidite-catalyzed conjugate addition of dialkylzinc reagents to acyclic α,β-unsaturated imides
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A new and practical way to introduce an alkyl fragment in the β-position of aliphatic carboxylic acid derivatives with high enantioselectivities by the use of a commercially available chiral ligand is reported. N-Acylpyrrolidinones, as simple derivatives
- Pineschi, Mauro,Del Moro, Federica,Di Bussolo, Valeria,Macchia, Franco
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p. 301 - 304
(2007/10/03)
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- Syntheses of new chiral bicyclic sultams and their use as auxiliaries in asymmetric conjugate addition of Grignard reagents
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Starting from L-aminoacids, 5-N-unsubstituted isothiazolo[4,5-c]isoxazole 4,4-dioxides have been synthesized and used as chiral auxiliaries in asymmetric conjugated additions of Grignard reagents to α,β-unsaturated carboxylic acids.
- Chiacchio, Ugo,Corsaro, Antonino,Gambera, Giovanni,Rescifina, Antonio,Piperno, Anna,Romeo, Roberto,Romeo, Giovanni
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p. 1915 - 1921
(2007/10/03)
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- Practical synthesis of (+)-alloisoleucine
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Subsequent treatment of N-crotoyl-(1S,2R)-bornane-10,2-sultam with EtMgCl, recrystallization of the product and saponification, afforded R-(-)- 3-methylpenthanoic acid which was used for acylation of (1R,2S)-bornane-10,2- sultam. The product was converted into N-[(2S,3R)-2-amino-3- methylpentanoyl](1R,2S)-bornane-10,2-sultam by hydroxyamination with 1- chloro-1-nitrosocyclohexane, followed by reduction of the hydroxylamine grouping. Saponification of the sultam imide provided (+)-alloisoleucine.
- Belzecki, Czeslaw,Trojnar, Jerzy,Chmielewski, Marek
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p. 2245 - 2252
(2007/10/03)
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- Pheromone synthesis, CXCVIII. Synthesis of (1S,2S,6S,10R)- and (1S,2R,6R,10R)-1,2,6,10-tetramethyldodecyl propanoate, the components of the sex pheromone of the pine sawfly, Microdiprion pallipes
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(1S,2S,6S,10R)- and (1S,2R,6R,10R)-1,2,6,10-tetramethyldodecyl propanoate (1 and 2), the components of the pheromone of Microdiprion pallipes, were synthesized from two chiral and nonracemic building blocks, (R)-3-tert-butoxycarbonyl-2-methylpropanoic acid (D) and (2R,6S)-7-acetoxy- 2,6-dimethyl-1-heptanol (G), by employing lipase-catalyzed kinetic resolution in a later step.
- Nakamura, Yoshihide,Mori, Kenji
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p. 2175 - 2182
(2007/10/03)
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- Asymmetric Michael addition reactions using ethyl (S)-4,4- dimethylpyroglutamate as a chiral auxiliary
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Ethyl 4,4-dimethylpyroglutamate has been used as a chiral auxiliary for α,β-unsaturated acids in Michael addition reactions. The conjugate addition of Grignard reagents to the amides in the presence of copper iodide, tetramethylene diamine (TMEDA) and trimethylsilyl chloride, proceeded with high yields and excellent stereoselectivities, yielding after hydrolysis enantiomerically pure β-substituted carboxylic acid derivatives.
- Ezquerra, Jesus,Prieto, Lourdes,Avendano, Carmen,Martos, Jose Luis,De La Cuesta, Elena
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p. 1575 - 1578
(2007/10/03)
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- Determination of the Enantiomeric Excesses of Chiral Acids by 19F NMR Studies of their Esters deriving from (R)-(+)-2-(Trifluoromethyl)benzhydrol
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15-Chiral acids were esterified with optically pure (R)-(+)-2-(trifluoromethyl)benzhydrol (R)-(+)-1, a readily available reagent.With respect to the carboxy group, the stereogenic centre is in the β-position in the case of the acids 5a-10a and 12a-16a, and in the α position in the case of the acids 17a-20a.The diastereomeric excesses of the corresponding esters 5b-10b and 12b-20b, respectively, were easily determined by means of 19F NMR.These d.e. values were in very good agreement with the e.e. values of the corresponding acids when the latter were known compounds.
- Brown, Eric,Chevalier, Christelle,Huet, Francois,Grumelec, Christelle Le,Leze, Antoine,Touet, Joel
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p. 1191 - 1194
(2007/10/02)
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- Asymmetric Conjugate Addition to Unsaturated Chiral Amido Alcohols Using Grignard Reagents Co-ordinated with Tertiary Amines or DBU. Preparation of Optically Active 3-Substituted Carboxylic Acids and (S)-(-)-Citronellol
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Optically active 3-substituted carboxylic acids and (S)-(-)-citronellol have been obtained by diastereoselective conjugate addition of Grignard reagents co-ordinated with 1,8-diazabicyclo-undec-7-ene (DBU) to chiral amidoalcohols derived from (S)-proline.
- Soai, Kenso,Machida, Hideaki,Yokota, Noriko
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p. 1909 - 1914
(2007/10/02)
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- EFFICIENT ASYMMETRIC HYDROGENATIONS OF CAMPHOR-SULTAM-IMIDE-CONJUGATED ALKENES.
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The trisubstituted olefinic bond of sultam-imides 2 was hydrogenated in the presence of Pd/C with >90percent diastereoface discrimination to give after saponification recovered auxiliary 7 and the β-substituted carboxylic acids 5 or 6 in high e.e..
- Oppolzer, Wolfgang,Mills, Robert J.,Reglier, Marius
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p. 183 - 186
(2007/10/02)
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- ASYMMETRIC CONJUGATE ADDITION REACTION BY THE USE OF (S)-γ-TRITYLOXYMETHYL-γ-BUTYROLACTAM AS A CHIRAL AUXILIARY
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(S)-γ-Trityloxymethyl-γ-butyrolactam (2) serves as a chiral auxiliary in the conjugate addition reaction of the corresponding imide (3) of α,β-unsaturated carboxylic acids with Grignard reagents in the presence of CuBr-SMe2 in THF to give, after hydrolysis, the β,β-disubstituted carboxylic acids (5) with predictable absolute configuration and high enantiomeric excess.
- Tomioka, Kiyoshi,Suenaga, Toshiro,Koga, Kenji
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p. 369 - 372
(2007/10/02)
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- ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED ALCANOIC ACIDS VIA HIGHLY STEREOSELECTIVE CONJUGATE ADDITIONS OF ORGANOCOPPER COMPOUNDS TO CHIRAL ENOATES
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Conjugate additions of organocopper compounds RCu*BF3 to enoates of sulfonamide-shielded alcohols 1x and 1n quite generally proceed with >99percent ee and >90percent yield.
- Helmchen, Guenter,Wegner, Guenter
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p. 6051 - 6054
(2007/10/02)
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- Asymmetric Conjugate Addition of Grignard Reagents in the Presence of Tertiary Amines to α,β-Unsaturated Amides Derived from (S)-2-(1-Hydroxy-1-methylethyl)pyrrolidine or (S)-Prolinol
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In the presence of tertiary amines, diastereoselective conjugate addition of Grignard reagents to α,β-unsaturated amides affords 3-substituted carboxylic acids of high enantiomeric excess (up to 89percent e.e.).
- Soai, Kenso,Machida, Hideaki,Ookawa, Atsuhiro
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p. 469 - 470
(2007/10/02)
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- ASYMMETRIC 1,4-ADDITIONS OF COORDINATED MeCu.BF3 TO CHIRAL ENOATES: ENANTIOSELECTIVE SYNTHESES OF (S)-(-)-CITRONELLIC ACID
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nBu3P- or cyanide-stabilized RCu.BF3 (R=Me, 4-Me-3-pentenyl) undergo efficient 1,4-additions to neopentylether-shielded trans-enoates.Thus chiral β-substituted carboxylic acids e.g. (S)-citronellic acid were obtained in high e.e. (Schemes 2 and 4).
- Oppolzer, Wolfgang,Moretti, Robert,Godel, Thierry,Meunier, Anne,Loeher, Heinz
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p. 4971 - 4974
(2007/10/02)
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- SYNTHESIS OF ALL OF THE FOUR POSSIBLE STEREOISOMERS OF 4,8-DIMETHYLDECANAL, THE AGGREGATION PHEROMONE OF THE FLOUR BEETLES
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The four stereoisomers of 4,8-dimethyldecanal were synthesized employing organometallic or electrolytic coupling reactions as the key step.The response of the red flour beetle, Tribolium castaneum, to the (4R,8R)-isomer was identical with that to the natural pheromone, while other isomers induced only very weak or no responses.The (4R,8R)-isomer is therefore the natural pheromone.
- Mori, Kenji,Kuwahara, Shigefumi,Ueda, Hiraki
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p. 2439 - 2444
(2007/10/02)
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