- Asymmetric conjugate addition to alkylidene malonates
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Dialkylzinc and trialkylaluminium reagents undergo conjugate addition to alkylidene malonates with 0.5% copper triflate as catalyst. The reaction could be made enantioselective by completing the reaction in the presence of 0.5-1.0 mol% of chiral phosphorus ligand. Enantiomeric excesses (e.e.s) of up to 73% could be attained with a ligand prepared from TADDOL and 2-naphthylcyclohexanol.
- Alexakis, Alexandre,Benhaim, Cyril
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- Enantioselective intermolecular free radical conjugate additions. Application of a pyrazole template
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An achiral pyrazole template has been evaluated in enantioselective conjugate radical additions. The enantioselectivity using the pyrazole template is inferior to those obtained from an oxazolidinone template. The two templates give products of opposite c
- Sibi, Mukund P.,Shay, John J.,Ji, Jianguo
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- Asymmetric Alkylation of a Chiral α-Amino Alkenenitrile
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Alkylation of the unsymmetric allylic anion generated from 2-(L-ephedrino)-4-phenylbut-3-enenitrile occurred exclusively at C-4 to give predominantly products having the 4R-configuration ; the stereoselectivity increased remarkably when the reaction was conducted in a mixture of hexamethylphosphoramide and lithium iodide.
- Fang, Jim-Min,Chang, Chih-Jung
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- An efficient synthetic route to chiral 4-alkyl-1,2,3,4-tetrahydroquinolines: Enantioselective synthesis of (R)-4-ethyl-1,2,3,4-tetrahydroquinoline
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An efficient synthetic route to non-racemic chiral 4-alkyl-1,2,3,4-tetrahydroquinoline is described. (4R)-4-Ethyl-1,2,3,4-tetrahydroquinoline was obtained by the organoaluminum promoted modified Beckmann rearrangement involving the oxime sulfonate of (3R)
- Mani, Neelakandha S.,Wu, Min
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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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- Ruthenium-catalyzed intramolecular arene C(sp2)-H amidation for synthesis of 3,4-dihydroquinolin-2(1 H)-ones
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We report the [Ru(p-cymene)(l-proline)Cl] ([Ru1])-catalyzed cyclization of 1,4,2-dioxazol-5-ones to form dihydroquinoline-2-ones in excellent yields with excellent regioselectivity via a formal intramolecular arene C(sp2)-H amidation. The reactions of the 2- and 4-substituted aryl dioxazolones proceeds initially through spirolactamization via electrophilic amidation at the arene site, which is para or ortho to the substituent. A Hammett correlation study showed that the spirolactamization is likely to occur by electrophilic nitrenoid attack at the arene, which is characterized by a negative ρ value of -0.73.
- Au, Chi-Ming,Ling, Cho-Hon,Sun, Wenlong,Yu, Wing-Yiu
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supporting information
p. 3310 - 3314
(2021/05/29)
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- Construction of enantioenriched 9H-Fluorene frameworks via a cascade reaction involving remote vinylogous dynamic kinetic resolution
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The benzylic C-H group of α,α-dicyanoolefins from 3-substituted 1-indanones could be significantly activated via transmission along the aromatic system, thus enabling dynamic kinetic resolution via a traditional reversible deprotonation- protonation process. Enantioenriched 9-substituted 9H-fluorene frameworks were finally constructed through an asymmetric vinylogous Michael addition to nitroolefins, followed by a cascade cyclization and oxidative aromatization process, under the catalysis of a chiral bifunctional thiourea-tertiary amine.
- Hu, Cui-Xia,Chen, Lin,Hu, Di,Song, Xue,Chen, Zhi-Chao,Du, Wei,Chen, Ying-Chun
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supporting information
p. 8973 - 8977
(2020/11/30)
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- Identification of an Esterase Isolated Using Metagenomic Technology which Displays an Unusual Substrate Scope and its Characterisation as an Enantioselective Biocatalyst
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Evaluation of an esterase annotated as 26D isolated from a marine metagenomic library is described. Esterase 26D was found to have a unique substrate scope, including synthetic transformations which could not be readily effected in a synthetically useful manner using commercially available enzymes. Esterase 26D was more selective towards substrates which had larger, more sterically demanding substituents (i. e. iso-propyl or tert-butyl groups) on the β-carbon, which is in contrast to previously tested commercially available enzymes which displayed a preference for substrates with sterically less demanding substituents (e.g. methyl group) at the β-carbon. (Figure presented.).
- Gavin, Declan P.,Murphy, Edel J.,Foley, Aoife M.,Castilla, Ignacio Abreu,Reen, F. Jerry,Woods, David F.,Collins, Stuart G.,O'Gara, Fergal,Maguire, Anita R.
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p. 2466 - 2474
(2019/03/11)
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- Enantioselective Hydrogenation of β,β-Disubstituted Unsaturated Carboxylic Acids under Base-Free Conditions
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An additive-free enantioselective hydrogenation of β,β-disubstituted unsaturated carboxylic acids catalyzed by the Rh-(R,R)-f-spiroPhos complex has been developed. Under mild conditions, a wide scope of β,β-disubstituted unsaturated carboxylic acids were hydrogenated to the corresponding chiral carboxylic acids with excellent enantioselectivities (up to 99.3% ee). This methodology was also successfully applied to the synthesis of the pharmaceutical molecule indatraline.
- Yan, Qiaozhi,Kong, Duanyang,Zhao, Wei,Zi, Guofu,Hou, Guohua
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p. 2070 - 2077
(2016/03/15)
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- Trialkyl Methanetricarboxylate as Dialkyl Malonate Surrogate in Copper-Catalyzed Enantioselective Propargylic Substitution
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The first copper-catalyzed enantioselective propargylation of trialkyl methantricarboxylate with propargylic alcohol derivatives was developed. The tricarboxylate unit in the obtained adducts could be easily transformed into a malonate moiety by treating with in situ generated NaOEt in excellent yield without racemization.
- Huang, Guanxin,Cheng, Cang,Ge, Luo,Guo, Beibei,Zhao, Long,Wu, Xiaoyu
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p. 4894 - 4897
(2015/10/12)
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- Facile palladium-catalyzed hydrocarboxylation of olefins without external CO gas
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An effective Pd-catalyzed hydrocarboxylation of olefins with phenyl formate and formic acid is described. A variety of carboxylic acids are obtained in good yields with high regioselectivities under operationally simple conditions without the use of toxic CO gas.
- Wang, Yang,Ren, Wenlong,Li, Jingfu,Wang, Haining,Shi, Yian
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supporting information
p. 5960 - 5963
(2015/02/19)
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- A rotary molecular motor gated by electrical energy
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DFT calculations predict that the chiral pentiptycene derivative E-1 possesses distinct rotational potential energy surfaces in the neutral vs the radical anionic (E-1?-) form such that continued electrochemical switching between E-1 and E-1su
- Kao, Chen-Yi,Lu, Hsiu-Feng,Chao, Ito,Yang, Jye-Shane
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supporting information
p. 6100 - 6103
(2015/02/19)
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- Influence of the position of the substituent on the efficiency of lipase-mediated resolutions of 3-aryl alkanoic acids
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Hydrolase-catalysed kinetic resolutions to provide enantioenriched α-substituted 3-aryl alkanoic acids are described. (S)-2-Methyl-3- phenylpropanoic acid (S)-1a was prepared in 96% ee by Pseudomonas fluorescens catalysed ester hydrolysis, while, Candida antarctica lipase B (immob) resolved the α-ethyl substituted 3-arylalkanoic acid (R)-1b in 82% ee. The influence of the position of the substituent relative to the ester site on the efficiency and enantioselectivity of the biotransformation is also explored; the same lipases were found to resolve both the α- and β-substituted alkanoic acids. Furthermore, the steric effect of substituents at the C2 stereogenic centre relative to that for their C3 substituted counterparts on the efficiency and stereoselectivity is discussed.
- Deasy, Rebecca E.,Moody, Thomas S.,Maguire, Anita R.
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p. 1480 - 1487
(2013/12/04)
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- The studies on chemoenzymatic synthesis of Femoxetine
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The studies on enzymatic kinetic resolution of 3-phenyl-4-pentenoic acid esters were performed. The obtained results demonstrated that the careful choice of biocatalyst and a reaction type are very important for successful enzymatic kinetic resolution. Ki
- Brodzka, Anna,Koszelewski, Dominik,Ostaszewski, Ryszard
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- Lipase catalysed kinetic resolutions of 3-aryl alkanoic acids
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Hydrolase catalysed kinetic resolutions leading to a series of 3-aryl alkanoic acids (≥94% ee) are described. Hydrolysis of the ethyl esters with a series of hydrolases was undertaken to identify biocatalysts that yield the corresponding acids with excellent enantiopurity in each case. Steric and electronic effects on the efficiency and enantioselectivity of the biocatalytic transformation were also explored.
- Deasy, Rebecca E.,Brossat, Maude,Moody, Thomas S.,Maguire, Anita R.
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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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- An unusual β-vinyl effect leading to high efficiency and enantioselectivity of the amidase, nitrile biotransformations for the preparation of enantiopure 3-arylpent-4-enoic acids and amides and their applications in synthesis
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(Chemical Equation Presented) Biotransformations of 3-arylpent-4- enenitriles catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst were studied, and an unusual β-vinyl effect of the substrate on
- Gao, Ming,Wang, De-Xian,Zheng, Qi-Yu,Wang, Mei-Xiang
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p. 9532 - 9535
(2007/10/03)
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- (S,S)-(+)-pseudoephedrine as chiral auxiliary in asymmetric conjugate addition and tandem conjugate addition/α-alkylation reactions
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(Chemical Equation Presented) Organolithium reagents undergo highly regio- and diastereoselective 1,4-addition to (S,S)-(+)-pseudoephedrine enamides furnishing the corresponding β-alkyl-substituted adducts in excellent yields and diastereoselectivities. In addition, the intermediate lithium enolates generated after the conjugate addition step undergo a highly diastereoselective alkylation reaction, furnishing α,β-dialkyl- substituted amides in high yields. The obtained adducts have been converted into chiral nonracemic β-alkyl- and α,β-dialkyl-substituted carboxylic acids and γ-alkyl- and β,γ-dialkyl-substituted alcohols using very simple and high-yielding procedures.
- Reyes, Efraim,Vicario, Jose L.,Carrillo, Luisa,Badia, Dolores,Uria, Uxue,Iza, Ainara
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p. 7763 - 7772
(2007/10/03)
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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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- Diastereoselective conjugate addition of 1-(α,β-unsaturated acyl)hydantoin with nucleophiles
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A diastereomeric conjugate addition of dialkylaluminum chloride to 1-(α,β-unsaturated acyl)hydantoin provided the corresponding alkyl adduct with inducted chirality in the β-position. Treatment of 1-(α,β-unsaturated acyl)hydantoin with Gilman reagent in the presence of Lewis acid also gave the same product. In this reaction, diethylaluminum chloride was the most effective Lewis acid and the absolute configuration of the major adduct at the β-position of acyl group depended on the kinds of existing metals.
- Yamaguchi, Jun-Ichi,Harada, Masakazu,Narushima, Takao,Saitoh, Asumi,Nozaki, Kanako,Suyama, Takayuki
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p. 6411 - 6415
(2007/10/03)
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- Direct competitive enzyme-linked immunosorbent assay for the determination of the highly polar short-chain sulfophenyl carboxylates
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A direct enzyme-linked immunosorbent assay for the detection of the short-chain sulfophenylcarboxylic acids (SPCs), the main metabolites of the linear alkylbenzene-sulfonates, is reported. Six SPCs (2C3, 2C 4, 3C4, 2C
- Estevez, M.-Carmen,Galve, Roger,Sanchez-Baeza, Francisco,Marco, M.-Pilar
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p. 5283 - 5293
(2008/02/02)
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- Stereoselective conjugate addition of mixed organoaluminum reagents to α,β-unsaturated N-acyloxazolidinones derived from carbohydrates
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The stereoselective synthesis of β-branched carboxylic acid derivatives was accomplished by conjugate addition of mixed organoaluminum reagents to chiral α,β-unsaturated N-acyloxazolidinones. Mixed organoaluminum reagents were generated in situ by transmetalation of Grignard or organolithium compounds with methylaluminum dichloride. Efficient stereocontrol was achieved using different bicyclic glycosamine-derived oxazolidinones, yielding alternatively (R)- or (S)-configured β-branched carboxylic acid derivatives.
- Elzner, Stephan,Maas, Steffen,Engel, Stefan,Kunz, Horst
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p. 2153 - 2164
(2007/10/03)
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- Pyran-2-ones and 5,6-dihydropyran-2-ones useful for treating hyperplasia and other diseases
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Certain 2H-pyran-2-ones are useful for treating benign prostatic hypertrophy or hyperplasia, prostatic cancer, alopecia, hirsutism, acne vulgaris and seborrhea.
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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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- Unprecedented effects of achiral oxazolidinones on enantioselective radical-mediated conjugate additions using a chiral zinc triflate
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equation presented A role of achiral oxazolidinones to enhance the enantioselectivity in reactions of N-cinnamoyloxazolidinones with alkyl radicals promoted by a chiral Lewis acid is described. Efficient enantioselective radical-mediated conjugate additio
- Murakata, Masatoshi,Tsutsui, Hideyuki,Hoshino, Osamu
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p. 299 - 302
(2007/10/03)
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- Asymmetric conjugate additions of chiral phosphonamide anions to α,β-unsaturated carbonyl compounds. A versatile method for vicinally substituted chirons
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Reactions of anions derived from chiral nonracemic allyl, crotyl, and cinnamyl bicyclic C2-symmetrical phosphonamides with α,β-unsaturated cyclic ketones, esters, lactones, and lactams take place at the γ-position of the reagents. The products are diastereomerically pure or enriched β-substituted carbonyl compounds. The method also provides easy access to vicinal substitution of as many as three stereogenic centers including in some cases quaternary carbon atoms, in a one-pot sequence.
- Hanessian, Stephen,Gomtsyan, Arthur,Malek, Nadia
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p. 5623 - 5631
(2007/10/03)
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- Conjugate addition of organolithium reagents to α,β-unsaturated carbocyclic acids
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Conjugate addition of primary, secondary, tertiary alkyi and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.
- Aurell, Maria Jose,Domingo, Luis Ramon,Mestres, Ramon,Munos, Elena,Zaragoza, Ramon Jose
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p. 815 - 830
(2007/10/03)
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- Enantioselective conjugate radical addition reactions mediated by chiral Lewis acid complexes of (R,R)-4,6-dibenzofurandiyl-2,2'-bis(4- phenyloxazoline) (DBFOX/Ph)
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A high-yielding synthesis (50% overall yield) of tridentate bisoxazoline ligand (R,R)-4,6-dibenzofurandiyl-2,2'-bis(4-phenyloxazoline) (DBFOX/Ph) was developed. DBFOX/Ph was subsequently tested in enantioselective conjugate radical additions onto 3-(3-phe
- Iserloh, Ulrich,Curran, Dennis P.,Kanemasa, Shuji
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p. 2417 - 2428
(2007/10/03)
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- Conjugate addition of organolithium reagents to α,β- unsaturated carboxylic acids
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Conjugate addition of primary, secondary, tertiary alkyl and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Substitution by methyl groups at the α-carbon strongly decreases reactivity, whereas deprotonation of the starting acid occurs almost exclusively with methyl substitution at the β-carbon of the 2- alkenoic acid.
- Aurell, Maria Jose,Mestres, Ramon,Munoz, Elena
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p. 6351 - 6354
(2007/10/03)
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- Stereocontrol in the intramolecular Buchner reaction of diazoketones
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Rhodium(II) acetate catalysed intramolecular Buchner cyclisation of a series of diazoketones 1 proceeds with excellent diastereoselectivity to produce the trans substituted azulenones 2, which exist as a rapidly equilibrating cycloheptatriene-norcaradiene system, from which the norcaradiene tautomers can be efficiently trapped as PTAD cycloadducts 4. The cyclisation-cycloaddition sequence can be conducted in either a stepwise or a tandem process, leading to the pentacyclic systems 4 as a single diastereomer in each case. In the reaction of diazoketone If intramolecular cyclopropanation competes with cyclisation to the aromatic ring.
- Maguire, Anita R.,Buckley, N. Rachael,O'Leary, Patrick,Ferguson, George
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p. 4077 - 4091
(2007/10/03)
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- SYNTHESIS OF ENANTIOMERICALLY PURE (5S)-4-AZA-2-OXA-6,6-DIMETHYL-7,10-METHYLENE-5-SPIRODECAN-3-ONE, A NOVEL CHIRAL OXAZOLIDIN-2-ONE FROM (-)-CAMPHENE FOR USE AS A RECYCLABLE CHIRAL AUXILIARY IN ASYMMETRIC TRANSFORMATIONS
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By an intramolecular nitreno-mediated route (-)-camphene is transformed into a novel spiro-oxazolidin-2-one whose efficiency as a chiral auxiliary is highlighted by the excellent levels of chiral induction attained in an array of asymmetric transformations such as the Diels-Alder, conjugate addition, aldol condensation, alkylation and acylation reactions.
- Banks, Malcolm R.,Cadogan, J. I. G.,Gosney, Ian,Grant, Keith J.,Hodgson, Philip K. G.,Thorburn, Paul
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p. 199 - 206
(2007/10/02)
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- Preparation of chiral indanones and dihydrocoumarins; Application to synthesis of (+)-3-(2,6-dimethoxyphenyl) pentanoic acid
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Chiral β-aryl carboxylic acids, prepared by Michael addition of organocuprates to chiral unsaturated imides, are transformed into chiral 3- alkyl-4-benzoyloxyindan-1-ones via two intramolecular acylations, with intermediate formation of chiral 3-alkylindanones and corresponding dihydrocoumarins. The 3-(S)-ethyl-4-benzoyloxyindanone is transformed into(+)-3-(S)-(2,6-dimethoxyphenyl)pentanoic acid.
- Stephan,Rocher,Aubouet,Pourcelot,Cresson
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- Enantioselective Michael Additions of Grignard Reagents to Cinnamamides deriving from N-Fluoroalkyl (R)-(-)-2-Aminobutan-1-ol. Determination of Diastereomeric Excess by means of 19F NMR
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N-Alkylation of (R)-(-)-2-aminobutan-1-ol 1 (a readily available reagent) with ortho-fluorobenzyl chloride, followed by reaction with cinnamoyl chloride, afforded the cinnamamide (R)-(+)-6.Michael addition of n-alkyl magnesium halides to the latter gave t
- Touet, Joel,Grumelec, Christelle Le,Huet, Francois,Brown, Eric
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p. 1469 - 1472
(2007/10/02)
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- Regio-, Stereo-, and Enantioselectivity in the Electrophilic Reactions of 2-Amino-4-phenyl-3-butenenitriles
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The allylic anion generated from 2-(N-methylanilino)-4-phenyl-3-butenenitrile (1) reacted with iodomethane and 3-bromo-1-chloropropane in THF/HMPA to give γ-substituted products exclusively, predominantly in the 2Z-configuration.Substitution of the N-methylanilino group with the methyl ether of L-(-)-ephedrine resulted in the generation of chiral aminonitrile 2.Lithiated 2 reacted sluggishly in THF with allyl bromide and benzyl chloride in the absence of HMPA to give the γ-substituted products predominantly in the 2Z-configuration, with little diastereoselectivity.The aminonitrile 3 prepared from cinnamaldehyde, L-(-)-ephedrine, and KCN was lithiated with 2 equiv of LDA resulting in high facial selectivity (76 - 100 percent diastereomeric excess) in alkylations in the presence of HMPA and LiI.Lithiated 3 reacted with propionaldehyde, benzaldehyde, and p-bromobenzaldehyde at -78 deg C to give the γ-addition products, predominantly in the 4R-configuration (64 -78 percent de).The stereochemistry of the isomers of each product was determined by chemical correlation and spectral methods including analyses of the CD spectra and X-ray diffraction.A bicyclic transition state C wherein lithium is chelated by both amino and alkoxy groups is proposed to interpret the observed stereoselectivity.
- Chang, Chih-Jung,Fang, Jim-Min,Liao, Li-Fan
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p. 1754 - 1761
(2007/10/02)
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- Asymmetric Michael additions of Grignard reagents to cinnamamides deriving from N-alkyl (R)-(-)-2-aminobutan-1-ol
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Reaction of cinnamoyl chloride with various N-alkyl derivatives of (R)-(-)-2-aminobutan-1-ol (a readily available reagent) afforded the corresponding cinnamamides. Michael additions of Grignard reagents to the latter, followed by acidic hydrolysis, yielde
- Touet,Baudouin,Brown
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p. 587 - 590
(2007/10/02)
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- l-Menthyl (2S)-2-phenyl-3-(p-anisyl)-(5Z)-benzylidene-4,6-dioxo-1,3-oxazine-2-ca rboxylate: A new chiral heterodiene and Michael acceptor
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The title homochiral oxazinedione has been synthesized from l-menthyl phenylglyoxylate in three steps and found to exhibit high diastereofacial selectivity (≥99%) when used as heterodiene and Michael acceptor.
- Sato,Nagashima,Furuya,Kaneko
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p. 1972 - 1974
(2007/10/02)
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- Reactions of 2-(2-propenyl)-3-chloromethyloxirane with benzene
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The reaction of 2-(2-propenyl)-3-chloromethyloxirane with benzene in the presence of aluminum chloride gives a 3:6:1 mixture of 1,4-dichloro-2-hexanone, 1-chloro-4-phenyl-2-hexanone, and 1-chloro-3,4-diphenyl-2-hexanone
- Akhmedov, M.A.,Sardarov, I.K.,Akhmedov, I.M.,Kostikov, R.R.,Babaev, N.M.,Shukyurova, M.B.
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p. 2025 - 2028
(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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- A FACILE ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED ALKANOIC ACID. THE HIGHLY STEREOSELECTIVE MICHAEL ADDITION OF GRIGNARD REAGENTS TO α,β-UNSATURATED CARBOXYLIC AMIDES DERIVED FROM L-EPHEDRINE
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The Michael addition of Grignard reagents to chiral α,β-unsaturated carboxylic amides derived from l-ephedrine affords highly optically active β-substituted alkanoic acids after acid hydrolysis.This high stereoselectivity is explained by considering the formation of rigid internal chelate complexes.
- Mukaiyama, Teruaki,Iwasawa, Nobuharu
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p. 913 - 916
(2007/10/02)
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