- DICARBOXIMIDE-BASED CLATHRATE DESIGN. HOST SYNTHESIS, INCLUSION FORMATION AND X-RAY CRYSTAL STRUCTURES OF A FREE HOST AND OF INCLUSION COMPOUDS WITH 2- AND 3-METHYLCYCLOHEXANONE, 3-METHYLCYCLOPENTANONE, BUTYRONITRILE, PROPAN-1-OL and (-)-FENCHONE GUESTS
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Crystalline host compounds consisting of a roof-shaped dicarboximide framework and pendant diarylethanol analogous subunits were synthesized and shown to form inclusion complexes with small organic molecules such as alcohols, amines, ketones or polar and apolar organic solvents.Clathrate efficiency and selectivity depend on the particular host structure.The crystal and molecular structures of a free host compound (2a) and inclusion compounds were determined by x-ray diffraction analysis.In all the structures, the hydroxyl group is involved in intramolecular hydrogen bonds and the host and guest molecules are held by lattice forces only.The channels and cavities left in the host matrix are large enough to allow disorder or high thermal displacement parameters of the guest molecules.The local packing coeffecients for all guests are 0.42 on average.
- Weber, Edwin,Reutel, Christiane,Foces-Foces, Concepcion,Llamas-Saiz, Antonio L.
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- Low ligand loading, highly enantioselective addition of phenylacetylene to aromatic ketones catalyzed by Schiff-base amino alcohols
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Schiff-base amino alcohols 7a,b derived from L-phenylglycine through three simple steps are found to be highly effective for the enantioselective addition of phenylacetylene to aromatic ketones. When the loading of 7b was 1 mol %, an ee value of up to 95% was obtained. However, when 7b was lowered to 0.1 mol %, a high ee value of 85% was still achieved. A practical solution to synthesize the optically active tertiary propargylic alcohols was described.
- Chen, Chao,Hong, Liang,Xu, Zhao-Qing,Liu, Lei,Wang, Rui
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- Synthesis and structure determination of novel chiral imine-alkoxytitanium complexes
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The imines 4 containing a diphenylcarbinol moiety serve as chiral ligands in novel enantiomerically pure imine-alkoxytitanium(IV) complexes. Depending on the molar ratio of the starting materials, imines 4 and titanium tetraisopropoxide, mono-chelated complexes 5 or bis-chelated complexes 6/7 result. The latter are formed diastereoselectively and the isomers 6 are main or exclusive products. Their (A) configuration is determined by a crystal-structure analysis of 6b. The bis-ligand complexes 6 or mixtures of 6/7, which are found to be remarkably stable, are used as precursors not only for the reactive dihalo complexes 8a/8b but also for the preparation of the mixed chloroisopropoxytitanium complex 8c.
- Fleischer, Ralf,Wunderlich, Hartmut,Braun, Manfred
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- Enantioselective zinc-mediated conjugate alkynylation of saccharin-derived 1-: Aza -butadienes
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The enantioselective 1,4-alkynylation of conjugated imines derived from saccharin with aryl- and alkyl-substituted terminal alkynes has been achieved. The reaction mediated by diethylzinc in the presence of a catalytic amount of a bis(hydroxy)malonamide chiral ligand provides the corresponding imines bearing a propargylic stereocenter with moderate yields and fair to excellent enantioselectivities. This journal is
- Blay, Gonzalo,Castilla, Alvaro,Sanz, David,Sanz-Marco, Amparo,Vila, Carlos,Mu?oz, M. Carmen,Pedro, José R.
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- Synthesis of acrylic polymer beads for solid-supported proline-derived organocatalysts
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A completely non-chromatographic and highly large-scale adaptable synthesis of acrylic polymer beads containing proline and prolineamides has been developed. Novel monomeric proline (meth)acrylates are prepared from hydroxyproline in only one step. Free-radical copolymerization then gives solid-supported proline organocatalysts directly in as little as two steps overall, without using any prefabricated solid supports, by using either droplet or dispersion polymerization. These affordable acrylic beads have highly favorable and adjustable swelling characteristics and are excellent reusable catalysts for organocatalytic reactions.
- Kristensen, Tor E.,Vestli, Kristian,Fredriksen, Kim A.,Hansen, Finn K.,Hansen, Tore
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- Simple primary β-amino alcohols as organocatalysts for the asymmetric Michael addition of β-keto esters to nitroalkenes
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Simple primary β-amino alcohols act as an efficient organocatalysts in the asymmetric Michael addition of β-keto esters with nitroalkenes affording highly pure chiral Michael adducts. Also, both enantiomers of the adducts were obtained, depending on the specific catalyst used and reaction temperature.
- Begum, Zubeda,Sannabe, Haruka,Seki, Chigusa,Okuyama, Yuko,Kwon, Eunsang,Uwai, Koji,Tokiwa, Michio,Tokiwa, Suguru,Takeshita, Mitsuhiro,Nakano, Hiroto
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p. 203 - 209
(2021/02/09)
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- Iron-catalysed enantioconvergent Suzuki-Miyaura cross-coupling to afford enantioenriched 1,1-diarylalkanes
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The first stereoconvergent Suzuki-Miyaura cross-coupling reaction was developed to afford enantioenriched 1,1-diarylalkanes. An iron-based complex containing a chiral cyanobis(oxazoline) ligand framework was best to obtain enantioenriched 1,1-diarylalkanes from cross-coupling reactions between unactivated aryl boronic esters and benzylic chlorides. Enhanced yields were obtained when 1,3,5-trimethoxybenzene was used as an additive, which is hypothesized to extend the lifetime of the iron-based catalyst. Exceptional enantioselectivities were obtained with challenging ortho-substituted benzylic chlorides. This journal is
- Tyrol, Chet C.,Yone, Nang S.,Gallin, Connor F.,Byers, Jeffery A.
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supporting information
p. 14661 - 14664
(2020/12/02)
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- Catalytic Asymmetric Intermolecular Cyclopropanation of a Ketone Carbene Precursor by a Ruthenium(II)-Pheox Complex
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The diazo derivative of acetonyl acetate is a useful basic skeleton for the synthesis of cyclopropyl ketones. The intermolecular cyclopropanations of diazo acetoxy acetone with olefins are accomplished by using a novel p-nitro-Ru(II)-diphenyl-Pheox catalyst to give the corresponding optically active cyclopropane derivatives in good yields (up to 95%) with excellent diastereoselectivities (up to 99:1) and enantioselectivities (up to 98% ee). (Figure presented.).
- Chi, Le Thi Loan,Suharto, Agus,Da, Ho Linh,Chanthamath, Soda,Shibatomi, Kazutaka,Iwasa, Seiji
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p. 951 - 955
(2019/01/25)
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- Addition of the Lithium Anion of Diphenylmethanol Methyl/Methoxymethyl Ether to Nonracemic Sulfinimines: Two-Step Asymmetric Synthesis of Diphenylprolinol Methyl Ether and Chiral (Diphenylmethoxymethyl)amines
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Addition of the lithium anion generated from diphenylmethanol methyl and methoxymethyl ether to nonracemic sulfinimines afforded the corresponding addition products in excellent diastereoselctivity and yields. Deprotection of the MOM as well as sulfinyl groups rendered the enantiopure (diphenylhydroxymethyl)amines in excellent yields. The procedure was applied for a two-step synthesis of diphenylprolinol, a privileged ligand in asymmetric catalysis.
- Reddy, Arava Amaranadha,Prasad, Kavirayani R.
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p. 10776 - 10785
(2018/09/12)
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- Hybrid-Type Squaramide-Fused Amino Alcohol Organocatalysts for Enantioselective Nitro-Aldol Reaction of Nitromethane with Isatins
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A series of hybrid-type squaramide-fused amino alcohol (SFAA) catalysts were synthesized, and their catalytic efficiency in the enantioselective nitro-aldol reaction of various isatins with nitromethane has been described. This transformation afforded chiral 3-substituted 3-hydroxyoxindoles in excellent chemical yields (up to 99 %) with high enantioselectivities (up to 95 % ee). The resulting chiral 3-hydroxyoxindoles can be further used as synthetic precursors for the synthesis of several natural products that have a broad spectrum of fascinating biological activities.
- Chennapuram, Madhu,Subba Reddy,Seki, Chigusa,Okuyama, Yuko,Kwon, Eunsang,Uwai, Koji,Tokiwa, Michio,Takeshita, Mitsuhiro,Nakano, Hiroto
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p. 1638 - 1646
(2017/04/06)
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- Simple primary β-amino alcohol catalyzed enantioselective Diels-Alder reaction of 3-hydroxy-2-pyridones
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The simple primary β-amino alcohol catalyzed Diels-Alder reaction of 3-hydroxy-2-pyridones as dienes with N-substituted maleimides to provide the highly substituted optically active isoquinuclidines as a single diastereomers in excellent enantioselectivities (up to 98%) with excellent chemical yields (up to 95%) was demonstrated. A range of simple β-amino alcohols were synthesized from the corresponding inexpensive amino acids and their catalytic activity was examined for this reaction.
- Takahashi, Toshihisa,Subba Reddy,Kohari, Yoshihito,Seki, Chigusa,Furuyama, Taniyuki,Kobayashi, Nagao,Okuyama, Yuko,Kwon, Eunsang,Uwai, Koji,Tokiwa, Michio,Takeshita, Mitsuhiro,Nakano, Hiroto
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p. 5771 - 5776
(2016/12/03)
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- Silyloxy Amino Alcohol Organocatalyst for Enantioselective 1,3-Dipolar Cycloaddition of Nitrones to α,β-Unsaturated Aldehydes
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The catalytic activity of a simple amino alcohol that contains a bulky super silyl group [i.e., tris(trimethylsilyl)silyl (TTMSS)] bonded to the oxygen atom at the γ-position along with a primary amine moiety was examined in the enantioselective 1,3-dipolar cycloaddition of nitrones to α,β-unsaturated aldehydes. The organocatalyst successfully provided optically active isoxazolidines in good chemical yields (up to 86 %) with excellent diastereoselectivities (endo/exo, up to 96:4) and enantioselectivities (up to 97 % ee). Furthermore, the obtained isoxazolidines were easily converted into γ-amino diols that contain three contiguous stereogenic centers.
- Otsuki, Teppei,Kumagai, Jun,Kohari, Yoshihito,Okuyama, Yuko,Kwon, Eunsang,Seki, Chigusa,Uwai, Koji,Mawatari, Yasuteru,Kobayashi, Nagao,Iwasa, Tatsuo,Tokiwa, Michio,Takeshita, Mitsuhiro,Maeda, Atushi,Hashimoto, Akihiko,Turuga, Kana,Nakano, Hiroto
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p. 7292 - 7300
(2015/11/25)
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- Chiral Bis(oxazolidine)pyridine-copper-catalyzed enantioselective friedel-crafts alkylation of indoles with nitroalkenes
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Catalytic asymmetric Friedel-Crafts reaction of indoles with nitroalkenes was catalyzed by the stereochemically tunable bis(oxazolidine)pyridine (PyBodine)-Cu(OTf)2 complex. Using the PyBodine(Val)-Cu(OTf) 2 catalyst gave the Friedel-Crafts ?adducts with highly enantioselective manner. For the 1,4-bis[(E)-2-nitrovinyl]benzene, the reaction proceeded in a meso-trick manner to give the chiral double Friedel-Crafts adduct with 97% enantiomeric excess. Georg Thieme Verlag Stuttgart New York.
- Sato, Toru,Arai, Takayoshi
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p. 349 - 354
(2014/03/21)
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- Efficient asymmetric addition of diethylzinc to aldehydes using C 2-novel chiral pyridine β-amino alcohols as chiral ligands
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A series of novel C2-symmetric chiral pyridine β-amino alcohol ligands have been synthesized from 2,6-pyridine dicarboxaldehyde, m-phthalaldehyde and chiral β-amino alcohols through a two-step reaction. All their structures were characterized by 1H NMR, 13C NMR and IR. Their enantioselective induction behaviors were examined under different conditions such as the structure of the ligands, reaction temperature, solvent, reaction time and catalytic amount. The results show that the corresponding chiral secondary alcohols can be obtained with high yields and moderate to good enantiomeric excess. The best result, up to 89% ee, was obtained when the ligand 3c (2S,2R)-2,2-((pyridine-2,6-diylbis(methylene)) bisazanediyl))bis(4-methyl-1,1-diphenylpentan-1-ol) was used in toluene at room temperature. The ligand 3g (2S,2R)-2,2-((1,3-phenylenebis(methylene)) bis(azanediyl))bis(4-methyl-1,1-diphenylpentan-1-ol) was prepared in which the pyridine ring was replaced by the benzene ring compared to 3c in order to illustrate the unique role of the N atom in the pyridine ring in the inductive reaction. The results indicate that the coordination of the N atom of the pyridine ring is essential in the asymmetric induction reaction. Copyright
- Zhang, Weijie,Tang, Ruiren,Yu, Huirong,Gao, Shu
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p. 545 - 551
(2014/07/07)
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- Stereochemical lability of azatitanacyclopropanes: Dynamic kinetic resolution in reductive cross-coupling reactions with allylic alcohols
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Azatitanacyclopropanes (titanaziridines) are shown to be stereochemically labile under reaction conditions for reductive cross-coupling. This fundamental property has been employed to realize highly selective asymmetric coupling reactions with allylic alcohols that proceed by dynamic kinetic resolution. The Royal Society of Chemistry 2013.
- Yang, Dexi,Micalizio, Glenn C.
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supporting information
p. 8857 - 8859
(2013/09/24)
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- Titanium-mediated cross-coupling reactions of imines with ketones or aldehydes: An efficient route for the synthesis of 1,2-amino alcohols
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The cross-coupling reactions of imines with ketones using Ti(O iPr)4/c-C5H9MgCl reagent lead to 1,2-amino alcohols after hydrolysis. The coupling reactions with aldehydes could also afford 1,2-amino alcohols, however, in some cases, aziridines were obtained as major products in a stereoselective manner.
- Fan, Guoqin,Liu, Yuanhong
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p. 5084 - 5087
(2012/09/25)
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- New phenylglycine-derived primary amine organocatalysts for the preparation of optically active warfarin
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In this work we present new, fully synthetic phenylglycinederived primary amine organocatalysts useful, for the onestep preparation, of optically active warfarin, an. important anticoagulant. Both enantiomeric forms of the catalysts are equally available and can be prepared by robust procedures without recourse to chromatographic purification. Together with a co-catalyst, particularly acetic acid or2,4-dinitrophen- ol, they can furnish warfarin in approximately 80 % ee and represent inexpensive alternatives to other primary amine organocatalysts such as the chiral diamines and. Cinchona-derived primary amines.
- Kristensen, Tor E.,Vestli, Kristian,Hansen, Finn K.,Hansen, Tore
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experimental part
p. 5185 - 5191
(2010/01/11)
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- 2,4-Dinitrophenol as an effective cocatalyst: Greatly improving the activities and enantioselectivities of primary amine organocatalysts for asymmetric aldol reactions
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Seven primary amine organocatalysts 1a-g were readily prepared from natural primary amino acids via two steps and then were used to catalyze the direct asymmetric aldol reaction, but they showed very poor enantioselectivities and activities. As an effective cocatalyst, 2,4-dinitrophenol (DNP) dramatically elevated the activities and enantioselectivities of these very inefficient primary amine organocatalysts. This remedial course to the very inefficient organocatalysts by selection and employment of the optimal cocatalyst was particularly cost-effective and environment-beneficial compared with de novo development of catalysts. The highest efficient organocatalytic system that was composed of If and DNP showed high enantioselectivities and good to high diastereoselectivities with a broad spectrum of seven ketones. The linear ketones and cyclopentanone got predominant syn products whereas cyclohexanone mainly gave anti products.
- Da, Chao-Shan,Che, Li-Ping,Guo, Qi-Peng,Wu, Feng-Chun,Xiao, Ma.,Jia, Ya-Ning
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experimental part
p. 2541 - 2546
(2009/08/07)
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- Highly efficient primary amine organocatalysts for the direct asymmetric aldol reaction in brine
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Organocatalytic systems made up of six primary amine organocatalysts, derived from natural primary amino acids, in combination with 2,4-dinitrophenol (DNP) have proven to be efficient in the presence of brine without further addition of organic solvents. The system formed by 1f and DNP was the most efficient one; it can catalyze the direct aldol reaction with a broad range of ketones and aromatic aldehydes, giving the corresponding aldol products in high yields with up to nearly perfect diastereo- and enantioselectivities (up to 99/1 syn/anti, >99% ee).
- Ma, Xiao,Da, Chao-Shan,Yi, Lei,Jia, Ya-Ning,Guo, Qi-Peng,Che, Li-Ping,Wu, Feng-Chun,Wang, Jun-Rui,Li, Wei-Ping
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experimental part
p. 1419 - 1424
(2009/12/04)
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- Design and evaluation of inclusion resolutions, based on readily available host compounds
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Resolution of enantiomers through selective crystallisation of diastereomeric inclusion compounds can extend the scope of traditional racemate resolution beyond salt forming compounds. To assess the practical value of this approach the literature was carefully screened and promising results were checked. Also an extensive range of new inclusion hosts suitable for resolution processes, derived from simple hydroxy- and amino acids were prepared and tested. Several techniques, including the Dutch Resolution approach utilizing mixtures of resolving agents, were applied. Over 70 potential resolving agents were tested in combinations with 34 racemates (over 100 racemates if literature results are included). Reproducibility of literature results was found to be problematic. Also the number of successful new resolutions found was very limited: only two efficient resolutions out of 1200 combinations of racemate and resolving agent tested in over 10.000 experiments! Crystal studies of representative combinations of resolving agents and inclusion compounds revealed some of the causes for the low rate of success in inclusion resolution. Compared to diastereomeric salts, the absence of strong electrostatic interactions substantially reduces the probability of forming crystals including both components. Molecular structure features allowing formation of intricate intramolecular and intermolecular H-bond networks were found to be responsible for inclusion crystal formation, and for the quality of the ensuing resolution through selective diastereomer crystallisation, in the successful cases. Whereas diastereomeric salt resolution continues to be of scientific and industrial interest, inclusion resolution should be viewed as of very limited scope; useful in specific instances, but lacking the wide applicability of classical resolution. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Mueller, Simona,Afraz, Marcel Cyrus,De Gelder, Rene,Ariaans, Gerry J. A.,Kaptein, Bernard,Broxterman, Quirinus B.,Bruggink, Alle
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p. 1082 - 1096
(2007/10/03)
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- Synthesis of heavily substituted 1,2-amino alcohols in enantiomerically pure form
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A simple and convenient methodology for the preparation of optically pure 2-amino-2-aryl-1,1-diphenylethanols is presented. Allylamine was found to produce the ring-opening of triaryloxiranes in a regioselective and a stereospecific fashion. Removal of the allyl protecting group provided the free 1,2-amino alcohols in enantiomerically pure form.
- Garcia-Delgado, Noemi,Reddy, Katamreddy Subba,Sola, Lluis,Riera, Antoni,Pericas, Miquel A.,Verdaguer, Xavier
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p. 7426 - 7428
(2007/10/03)
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- Stereoselective alkylations in rigid systems. Effect of remote substituents on π-facial additions to lactam enolates. Stereoelectronic and steric effects
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A series of chiral bicyclic lactams has been studied by both experiment and ab initio molecular orbital calculations, The facial selectivity of the alkylation of their enolates shows a high degree of endo or exo entry, depending upon certain substituents and their positions in the lactams. The suggested reasons for the exo or endo selectivity for alkylation were determined to be purely electronic or purely steric in certain instances, The results of the selectivity study now allow the asymmetric synthesis of various ketones, acids, and pyrrolidines in either enantiomeric form based on the choice of lactam employed.
- Meyers,Seefeld, Mark A.,Lefker, Bruce A.,Blake, James F.,Williard, Paul G.
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p. 7429 - 7438
(2007/10/03)
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- Asymmetric Induction in Intramolecular SN2' Reaction. Enantioselective Synthesis of Cyclopenta[b]benzofuran with Chiral Lithium Alkoxides
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An enantioselective intramolecular cyclization of the bis-phenyllithium species 3 was attained by addition of chiral lithium alkoxides to produce a cyclopenta[b]benzofuran 2 with high % ee's up to 87 %.
- Nishiyama, Hisao,Sakata, Naoya,Motoyama, Yukihiro,Wakita, Hisanori,Nagase, Hiroshi
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p. 1147 - 1148
(2007/10/03)
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- Synthesis of Optically Active Siloxycyclopropanes by Asymmetric Catalysis, I. - Influence of the Catalyst on the Cyclopropanation of (Z)-1-Phenyl-1-(trimethylsiloxy)prop-1-ene
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The cyclopropanation of silyl enol ether 1a with methyl diazoacetate (2a) and diazoesters 2b-d in the presence of optically active copper salicylimine complexes 4-Cu was systematically studied.Up to 88percent enantiomeric excess in products 3 were obtained by employing the appropriate reaction conditions and the optimal catalyst ligands.Thus, for the first time respectable optical yields were achieved in asymmetric cyclopropanations of silyl enol ethers with easily available copper-Schiff base catalysts.The ring opening of the separated diastereomers of 3a employing nBu4NF provided methyl γ-oxocarboxylate 6a in good optical purity.This demonstrates that this process occurs without racemization and also that 3a is formed with the same absolute configuration at C-1. - Key Words: Cyclopropanecarboxylates, 2-silyloxy, methyl / Cycloaddition / Enantioselectivity / Asymmetric catalysis / Copper-Schiff base complexes, chiral
- Dammast, Franziska,Reissig, Hans-Ulrich
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p. 2449 - 2456
(2007/10/02)
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- ASYMMETRIC SYNTHESES VI: ASYMMETRIC ALDOL REACTION OF D-CAMPHOR IMINE DERIVED FROM BENZYLAMINE
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Addition of the D-camphor imine of benzylamine to a variety of aldehydes or ketones gives diastereoselectivites ranging from 16-70percent.The d.e. value is attributed by the difference of the orientation of C-11 groups.The rotation of (5e) indicates that addition reaction occurs from the pro-R face of lithium derivative (2).
- Yaozhong, Jiang,Guilan, Liu,Jingen, Deng
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p. 1291 - 1298
(2007/10/02)
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