- Inversions in asymmetric conjugate addition reaction of cyclic enones catalyzed by the Cu/NHC-AgX system: Factors affecting the stereoselective formation of both enantiomers
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A switchable enantioselectivity was achieved in a Cu-catalyzed asymmetric conjugate addition (ACA) reaction. The ethylene-bridged, hydroxyamide-functionalized NHC-AgI complex, readily accessible from a chiral β-amino alcohol, was found to be a versatile c
- Nakano, Yuki,Sakaguchi, Satoshi
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p. 407 - 416
(2017/07/28)
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- Electrochemical Coupling of Biomass-Derived Acids: New C8 Platforms for Renewable Polymers and Fuels
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Electrolysis of biomass-derived carbonyl compounds is an alternative to condensation chemistry for supplying products with chain length >C6for biofuels and renewable materials production. Kolbe coupling of biomass-derived levulinic acid is used to obtain 2,7-octanedione, a new platform molecule only two low process-intensity steps removed from raw biomass. Hydrogenation to 2,7-octanediol provides a chiral secondary diol largely unknown to polymer chemistry, whereas intramolecular aldol condensation followed by hydrogenation yields branched cycloalkanes suitable for use as high-octane, cellulosic gasoline. Analogous electrolysis of an itaconic acid-derived methylsuccinic monoester yields a chiral 2,5-dimethyladipic acid diester, another underutilized monomer owing to lack of availability.
- Wu, Linglin,Mascal, Mark,Farmer, Thomas J.,Arnaud, Sacha Pérocheau,Wong Chang, Maria-Angelica
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p. 166 - 170
(2017/01/17)
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- Enantioselectivity switch in copper-catalyzed conjugate addition reactions under the influence of a chiral N-heterocyclic carbene-silver complex
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The asymmetric 1,4-addition of Et2Zn to 2-cyclohexen-1-one using a Cu(i) salt/N-heterocyclic carbene (NHC)-Ag complex catalytic system afforded optically active 3-ethylcyclohexanone. The reversal of enantioselectivity using the same catalytic s
- Matsumoto, Keitaro,Nakano, Yuki,Shibata, Naoatsu,Sakaguchi, Satoshi
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p. 7755 - 7759
(2016/02/05)
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- Cp2ZrMeCl: A Reagent for Asymmetric Methyl Addition
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The use of Cp2ZrMeCl is described as a source of nucleophilic methyl in asymmetric catalysis. This easily prepared reagent is bench stable, weighable in air, and generally useful in highly enantioselective copper-catalyzed addition reactions at room temperature. Methyl is successfully (generally >90% ee) added in 1,4-additions to cyclic and acyclic α,β-unsaturated ketones to provide tertiary and quaternary centers. Examples of catalyst controlled diastereoselective 1,6-addition and dynamic kinetic asymmetric allylic alkylation reactions are also reported. The reagent is used in the catalytic asymmetric synthesis of naturally occurring fragrance (R)-(-)-muscone (82% yield, 91% ee).
- Garrec, Kilian,Fletcher, Stephen P.
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supporting information
p. 3814 - 3817
(2016/08/16)
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- Hydroxy-amide functionalized azolium salts for Cu-catalyzed asymmetric conjugate addition: Stereocontrol based on ligand structure and copper precatalyst
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A series of hydroxy-amide functionalized azolium salts have been designed and synthesized for Cu-catalyzed asymmetric conjugate addition reaction. The (CH2)2-bridged hydroxy-amide functionalized azolium ligand precursors 2, in addition to the previously reported CH2-bridged azolium salts 1, have been prepared from readily available enantiopure β-amino alcohols. The combination of a Cu species with 1 or 2 efficiently promoted the 1,4-addition reaction of cyclic enones with dialkylzincs. For example, the reaction of 2-cyclohepten-1-one (17) with Bu2Zn in the presence of catalytic amounts of Cu(OTf)2 and 1 gave (S)-3-butylcycloheptanone (20) in 99% yield and 96% ee. On the other hand, when the reaction was carried out under the influence of Cu(OTf)2 combined with 2, (R)-20 in preference to (S)-20 was obtained in 98% yield and 80% ee. In this manner, the enantioselecvity was switched by controlling the structure of chiral ligand. Additionally, the reversal of enantioselectivity was also achieved by changing the Cu precatalyst from Cu(OTf)2 to Cu(acac)2 with the same ligand. The combination of Cu(acac) 2 with CH2-bridged azolium salt 1 in the reaction of 17 with Bu2Zn led to formation of (R)-20 as a major product in 55% yield and 80% ee. This result was in contrast to the Cu(OTf)2/1 catalytic system, where the 1,4-adduct with opposite configuration was obtained. Moreover, use of the Cu(acac)2/2 catalytic system produced (S)-20, while (R)-20 was formed by the Cu(OTf)2/2 catalytic system. Thus, it was found that either varying the linker of the chiral ligands or changing the counterion of Cu species between a OTf and acac ligand initially on the metal led to dual enantioselective control in the 1,4-addition reaction.
- Shibata, Naoatsu,Yoshimura, Misato,Yamada, Haruka,Arakawa, Ryuichi,Sakaguchi, Satoshi
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experimental part
p. 4079 - 4086
(2012/06/04)
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- Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones using a novel N,N,P-Cu(II) complex
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Enantioselective copper-catalyzed 1,4-additions of dialkylzincs to enones were carried out in the presence of 1 mol % of Cu(OTf)2 and 2.5 mol % of an N,N,P-ligand possessing a tert-butyl group at the adjacent position of the nitrogen of pyridin
- Ebisu, Yasuhiro,Kawamura, Kenjiro,Hayashi, Masahiko
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experimental part
p. 959 - 964
(2012/09/25)
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- Preparation and characterization of new C2- and C 1-symmetric nitrogen, oxygen, phosphorous, and sulfur derivatives and analogs of TADDOL. part i
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The chloro alcohols 4-6 derived from TADDOLs (=α,α, α′,α′-tetraaryl-1,3-dioxolan-4,5-dimethanols) are used to prepare corresponding sulfanyl alcohols, ethers, and amines (Scheme 1 and Table 1). The dithiol analog of TADDOL and derivatives thereof, 45-49,
- Pichota, Arkadius,Gramlich, Volker,Beck, Albert K.,Seebach, Dieter
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experimental part
p. 1239 - 1272
(2012/09/21)
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- Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones followed by trapping with allyl iodide derivatives
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Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones proceeded in the presence of 0.1 mol% of Cu(OTf)2 and 0.25 mol% of an N,N,P-ligand containing a quinoline moiety to afford the corresponding conjugated adducts in 99%ee. The intermediate zinc enolates were trapped with substituted allyl iodides to give disubstituted ketones with high diastereoselectivity and enantioselectivity.
- Kawamura, Kenjiro,Fukuzawa, Hitomi,Hayashi, Masahiko
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experimental part
p. 640 - 647
(2011/08/06)
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- Copper-catalyzed asymmetric 1,4-conjugate addition of dialkylzinc to enones
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Asymmetric 1,4-conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)-6,6'-Br2-BINOL(1f), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy2NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to84%ee) and isolated yield (up to 94%) under mild reaction conditions.
- Gou, Shaohua,Ye, Zhongbin,Shi, Leiting,Qing, Dayong,Zhang, Wen,Wang, Yuliang
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experimental part
p. 517 - 522
(2010/10/18)
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- Thieme chemistry journal awardees - Where are they now? Asymmetric br?nsted acid catalyzed transfer hydrogenations
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Asymmetric hydrogenations are of great importance in the synthesis of optically active amines. This account highlights the development of the first metal-free transfer hydrogenation that is both highly enantioselective and inspired by natures dehydrogen?ase. Further focus is given to the extension of this bioinspired process to provide a variety of valuable, biologically active products and natural products under mild reaction conditions. Georg Thieme Verlag Stuttgart - New York.
- Rueping, Magnus,Sugiono, Erli,Schoepke, Fenja R.
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scheme or table
p. 852 - 865
(2010/07/06)
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- ORGANIC SALTS AND METHOD FOR PRODUCING CHIRAL ORGANIC COMPOUNDS
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The invention relates to a method for producing chiral organic compounds by asymmetric catalysis, using ionic catalysts comprising a chiral catalyst anion. The claimed method is suitable for reactions which are carried out over cationic intermediate stages, such as iminium ions or acyl pyridinium ions. The invention enables the production of chiral compounds with high ee values, that until now could only be obtained by means of costly purification methods.
- -
-
Page/Page column 7; 8
(2009/02/11)
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- Asymmetric total synthesis of PDIM A: A virulence factor of Mycobacterium tuberculosis
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The first asymmetric synthesis of phthiocerol was achieved in 15 simple steps and 5.6% overall yield by applying three efficient catalytic transformations. The construction of building block 4 started with the copper/phosphoramidite-catalyzed asymmetric conjugate addition of Me 2Zn to cycloheptenone, followed by in situ ethylation. Baeyer Villiger oxidation using excess m-chloroperoxybenzoic acid (mCPBA) followed by treatment of the resulting lactone 7 with K2C03 in MeOH led to the formation of the linear product. Treatment with TBAF followed by a Fleming-Tamao oxidation using KHCO3 and H2O2, resulted in the formation of the corresponding hydroxy ketones, which could be separated by column chromatography affording 16 as a pure isomers.
- Casas-Arce, Eva,Ter Horst, Bjorn,Feringa, Ben L.,Minnaard, Adriaan J.
-
supporting information; experimental part
p. 4157 - 4159
(2009/05/07)
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- Novel N,N,P-tridentate ligands for the highly enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones
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(Chemical Equation Presented) Use of 0.25 mol % of the N,N,P-tridentate ligand containing the 2-quinolyl moiety (1 and 2) and 0.1 mol % of Cu(OTf) 2 enabled the enantioselective 1,4-addition of dialkylzincs to cyclic enones to produce 1,4-adduc
- Kawamura, Kenjiro,Fukuzawa, Hitomi,Hayashi, Masahiko
-
supporting information; scheme or table
p. 3509 - 3512
(2009/05/07)
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- Highly enantioselective transfer hydrogenation of α,β- unsaturated ketones
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We describe an efficient and highly enantioselective conjugate transfer hydrogenation of α,β-unsaturated ketones that is catalyzed by a salt made from tert-butyl valinate and a recently introduced powerful chiral phosphoric acid catalyst (TRIP). Copyright
- Martin, Nolwenn J. A.,List, Benjamin
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p. 13368 - 13369
(2007/10/03)
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- Asymmetric conjugate addition of metal alkyl reagents catalyzed by copper complexes with BINPO: A hemilabile P,O-heterobidentate axially chiral ligand
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We herein report the use of a new class of P,O-bidentate arylphosphine ligand for the asymmetric copper catalyzed conjugate addition of dialkylzinc and trialkylaluminium with the enantiomeric excesses reaching 91% while (R)-muscone was obtained with 77% ee.
- Fuchs, Nicolas,D'Augustin, Magali,Humam, Munir,Alexakis, Alexandre,Taras, Rossana,Gladiali, Serafino
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p. 3143 - 3146
(2007/10/03)
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- Highly enantioselective copper(I)-phosphoramidite-catalysed additions of organoaluminium reagents to enones
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Simple phosphoramidite ligands afford good to excellent levels of enantioselectivity in 1,4-additions of AIR3 species to enones; sequential carboalumination-ACA cascades are possible. The Royal Society of Chemistry 2005.
- Alexakis, Alexandre,Albrow, Victoria,Biswas, Kallolmay,D'Augustin, Magali,Prieto, Oscar,Woodward, Simon
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p. 2843 - 2845
(2007/10/03)
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- Highly Enantioselective 1,4-Addition of Diorganozinc Reagents to Cyclic Enones Using Chiral Diphosphite Ligands Derived from H8-Binaphthol
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(Matrix Presented) High enantioselectivities have been achieved in the 1,4-addition of dialkylzincs to 2-cyclopentenone, 2-cyclohexenone, and 2-cycloheptenone with ee values up to 99% by using chiral aryl diphosphite ligands derived from H8-binaphthol.
- Liang, Liang,Au-Yeung, Terry T.-L.,Chan, Albert S. C.
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p. 3799 - 3801
(2007/10/03)
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- Solvolysis of 4-methylcyclohexylidenemethyliodonium salt: Chirality probe approach to a primary vinyl cation intermediate
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Optically active 4-methylcyclohexylidenemethyl(aryl)iodonium tetrafiuoroborate (1·BF4-) was prepared and its solvolysis was carried out at 60 °C in various solvents. The main product is optically active 4-methylcycloheptanone (or its enol derivative) in unbuffered solvents, accompanied by the iodoarene. The rearranged product always maintains the optical purity of the starting 1. Its stereochemistry conforms to a mechanism involving the rearrangement via the σ-bond participation in departure of the nucleofuge, followed by trapping of the resulting chiral 5-methylcyclohept-1-enyl cation with a nucleophilic solvent. That is, the achiral, primary vinyl cation is not involved during the reaction. The unrearranged substitution product is also obtained in a minor fraction in unbuffered methanol, ethanol, and acetic acid, but not in trifluoroethanol or hexafluoro-2-propanol: the methoxy product from methanolysis is largely racemized, but the acetolysis product is obtained mainly via retention of configuration. Reactions of 1 with bromide, acetate, and trifluoroacetate in chloroform give unrearranged substitution products in different degrees of inversion. These unrearranged products are concluded to be formed via the direct nucleophilic substitutions. Added bases such as sodium acetate in methanol lead to the unrearranged methoxy products of complete racemization, which is ascribed to the α elimination (to give an alkylidene-carbene) followed by the solvent insertion.
- Fujita, Morifumi,Sakanishi, Yuichi,Nishii, Masayoshi,Yamataka, Hiroshi,Okuyama, Tadashi
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p. 8130 - 8137
(2007/10/03)
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- Chiral bicyclic phosphoramidites - A new class of ligands for asymmetric catalysis
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The development of new ligands for catalytic asymmetric C-C bond formation is of great interest to organic synthesis. We describe here a new class of chiral phosphoramidites that embody one or two binaphthol units attached to an achiral azabicyclic [3.3.1] or [3.3.0] framework. These ligands were easily accessible from (R)-1,1′-binaphthyl-2,2′-dioxaphosphorchloridite (4) and the corresponding heterobicyclic core 1, 2, or 3. They were employed in enantioselective Cu-catalyzed additions of different dialkylzinc reagents to cyclic and acyclic enones. The chiral ketones were obtained with an enantiomeric ratio up to 91:9. The choice of the best ligand proved to be strongly dependent on each substrate. In addition, ligand 6 was found to be the most suitable for Rh-catalyzed hydrogenations of α,β-unsaturated esters, giving rise to dimethyl 2-methylsuccinate and methyl N-acetylalaninate with enantiomer ratios up to 95:5.
- Huttenloch, Oliver,Spieler, Jan,Waldmann, Herbert
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p. 671 - 675
(2007/10/03)
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- Novel biphenol phosphoramidite ligands for the enantioselective copper-catalyzed conjugate addition of dialkyl zincs
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Phosphoramidite ligands, based on a chiral amine and atropoisomerically flexible biphenols, induce high enantioselectivities (ee's up to 98%) in the copper-catalyzed conjugate addition of dialkyl zinc reagents to a variety of Michael acceptors.
- Alexakis,Rosset,Allamand,March,Guillen,Benhaim
-
p. 1375 - 1378
(2007/10/03)
-
- An asymmetric conjugate addition reaction of lithium organocopper reagent controlled by a chiral amidophosphine
-
Examination of the behaviors of the chiral amidophosphines 1-14 in the asymmetric conjugate addition reaction of lithium organocopper with chalcone and cycloalkenone revealed that the reaction efficiency is governed by many factors including copper salt, solvent, molecular ratio of copper and organolithium, and the structure of the substrate. The reaction with cycloalkenone gave the adduct in up to 94% ee under the stoichiometric conditions.
- Kanai, Motomu,Nakagawa, Yuichi,Tomioka, Kiyoshi
-
p. 3831 - 3842
(2007/10/03)
-
- Enantioselective 1,4-Addition of Aliphatic Grignard Reagents to Enones Catalyzed by Readily Available Copper(I) Thiolates Derived from TADDOL
-
Two simple thiols derived from the parent TADDOL, α,α,α + ′,α + ′-tetraphenyl-2,2-dimethyl-1,3-dioxolan-4,5-dimethanol, are used to prepare Cu1 complexes C and D to catalyze (0.05 equiv.) 1,4-additions of Grignardreagents RMgCl to cyclic enones
- Seebach, Dieter,Jaeschke, Georg,Pichota, Arkadius,Audergon, Laurent
-
p. 2515 - 2519
(2007/10/03)
-
- Ring Opening of Cyclopropylketones Induced by Photochemical Electron Transfer
-
Depending on the substitution pattern of cyclopropylketones, the photochemically induced electron transfer of tertiary amines to cyclopropylketones leads either to the formation of 3-substituted cycloalkanones or to ring expanded products.
- Cossy, Janine,Furet, Nathalie,BouzBouz, Samir
-
p. 11751 - 11764
(2007/10/02)
-
- Asymmetric conjugate addition of organocopperamidophosphine reagents to cycloalkenones
-
Mediated by a noncovalently bound chiral amidophosphine ligand 1, reaction of organocoppers with cycloalkenones 2 afforded the corresponding 3-substituted cycloalkanones 3 in 95-68% ee.
- Kanai, Motomu,Tomioka, Kiyoshi
-
p. 895 - 898
(2007/10/02)
-
- Enantioselective conjugate addition to cyclic enones with scalemic lithium organo(amido)cuprates, part IV. Relationship between ligand structure and enantioselectivity
-
Scalemic lithium amides derived from primary and secondary amines react with organocopper compounds in ether or dimethyl sulfide to form lithium organo(amido)cuprates capable of enantioselective conjugate addition to 2-cycloalkenones. The most successful heterocuprate, in which the chiral ligand is (S)-N-methyl-1-phenyl-2-(1-piperidinyl)ethanamine, (S)-MAPP, 13, reacts with cyclic enones to form products with up to 97% ee. Nonlinear asymmetric induction was observed with the cuprate formed from ligand 13.
- Rossiter, Bryant E.,Eguchi, Masakatsu,Miao, Guobin,Swingle, Nicole M.,Hernandez, Amelia E.,Vickers, Denise,Fluckiger, Ezdan,Greg Patterson,Vasavi Reddy
-
p. 965 - 986
(2007/10/02)
-
- Photochemical ring opening of cyclopropyl ketones induced by electron transfer
-
Irradiation of substituted bicyclo[n.1.0]alkan-2-ones at 254 nm in the presence of triethylamine and lithium perchlorate (LiClO4) can lead to cyclopropane ring opening with cleavage of the C(1)-C(n +2) (ring enlargement) or C(1)-C(n+3) bonds.
- Cossy, Janine,Furet, Nathalie
-
p. 8107 - 8110
(2007/10/02)
-
- ENANTIOSELECTIVE CONJUGATE ADDITION TO CYCLIC ENONES WITH (S)-MAPP-CUPRATES
-
Chiral amidocuprates, formed from CuI, n-butyl or methyl lithium and (S)-N-methyl-1-phenyl-2-(1-piperidinyl)ethanamine, (S)-MAPP, react enantioselectively with 5, 6, 7 and 8-membered cyclic enones to give products with up to 97percent e.e.The synthesis of (S)-MAPP is also reported.
- Rossiter, Bryant E.,Eguchi, Masakatsu,Hernandez, Amelia E.,Vickers, Denise,Medich, John,et al.
-
p. 3973 - 3976
(2007/10/02)
-