- Symbiotic reagent activation: Oppenauer oxidation of magnesium alkoxides by silylglyoxylates triggers second-stage aldolization
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The treatment of silylglyoxylates with magnesium alkoxides at ambient temperature results in symbiotic Oppenauer oxidation of the alkoxide and Meerwein-Ponndorf-Verley reduction of the silylglyoxylate. The reduced silylglyoxylate undergoes subsequent [1,2
- Linghu, Xin,Satterfield, Andrew D.,Johnson, Jeffrey S.
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Read Online
- 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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Read Online
- Energy-Transfer-Mediated Photocatalysis by a Bioinspired Organic Perylenephotosensitizer HiBRCP
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Energy transfer plays a special role in photocatalysis by utilizing the potential energy of the excited state through indirect excitation, in which a photosensitizer determines the thermodynamic feasibility of the reaction. Bioinspired by the energy-transfer ability of natural product cercosporin, here we developed a green and highly efficient organic photosensitizer HiBRCP (hexaisobutyryl reduced cercosporin) through structural modification of cercosporin. After structural manipulation, its triplet energy was greatly improved, and then, it could markedly promote the efficient geometrical isomerization of alkenes from the E-isomer to the Z-isomer. Moreover, it was also effective for energy-transfer-mediated organometallic catalysis, which allowed realization of the cross-coupling of aryl bromides and carboxylic acids through efficient energy transfer from HiBRCP to nickel complexes. Thus, the study on the relationship between structural manipulation and their photophysical properties provided guidance for further modification of cercosporin, which could be applied to more meaningful and challenging energy-transfer reactions.
- Zhang, Yan,Xia, Mingze,Li, Min,Ping, Qian,Yuan, Zhenbo,Liu, Xuanzhong,Yin, Huimin,Huang, Shuping,Rao, Yijian
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p. 15284 - 15297
(2021/11/01)
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- Highly Enantioselective Iridium-Catalyzed Hydrogenation of Conjugated Trisubstituted Enones
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Asymmetric hydrogenation of conjugated enones is one of the most efficient and straightforward methods to prepare optically active ketones. In this study, chiral bidentate Ir-N,P complexes were utilized to access these scaffolds for ketones bearing the stereogenic center at both the α- and β-positions. Excellent enantiomeric excesses, of up to 99%, were obtained, accompanied with good to high isolated yields. Challenging dialkyl substituted substrates, which are difficult to hydrogenate with satisfactory chiral induction, were hydrogenated in a highly enantioselective fashion.
- Peters, Bram B. C.,Jongcharoenkamol, Jira,Krajangsri, Suppachai,Andersson, Pher G.
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supporting information
p. 242 - 246
(2021/01/13)
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- Cobalt-Catalyzed Asymmetric 1,4-Hydroboration of Enones with HBpin
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Herein, a series of new 8-OIQ cobalt complexes were synthesized and used for cobalt-catalyzed chemo- and enantioselective 1,4-hydroboration of enones with HBpin to access chiral β,β-disubstituted ketones with good to excellent chemo- and enantioselectivties. This protocol is operationally simple and shows a broad substrate scope.
- Ren, Xiang,Lu, Zhan
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supporting information
p. 8370 - 8374
(2021/11/01)
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- Anti-Hydroarylation of Activated Internal Alkynes: Merging Pd and Energy Transfer Catalysis
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A general catalytic anti-hydroarylation of electron-deficient internal alkynes compatible with both electron-poor and electron-rich aryl reagents is reported. This selectivity is achieved through a sequential syn-carbopalladation of the alkyne by an Ar-Pd species, followed by a tandem, Ir-photocatalyzed, counter-thermodynamic E → Z isomerization. The use of ortho-substituted boronic acids enables direct access to pharmaceutically relevant heterocyclic cores via a cascade process. Mechanistic insight into the involvement of Ar-Pd versus Pd-H as an active species is provided.
- Carretero, Juan C.,Corpas, Javier,Gómez Arrayás, Ramón,Mauleón, Pablo
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supporting information
(2020/09/09)
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- Copper-Photocatalyzed Contra-Thermodynamic Isomerization of Polarized Alkenes
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The contra-thermodynamic isomerization of α- and β-substituted cinnamate derivatives catalyzed by the Cu(OAc)2/rac-BINAP complex under blue light irradiation is reported. The use of an oxazolidinone template, which favored the complexation of the copper catalyst to the substrate, allowed the E → Z isomerization of the catalytically formed chromophore under simple and robust reaction conditions in good to excellent ratios. The mechanism of this process based on the transient formation of a chromophore was also studied.
- Bouillon, Jean-Philippe,Brégent, Thibaud,Poisson, Thomas
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supporting information
p. 7688 - 7693
(2020/10/09)
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- Catalytic Asymmetric Transfer Hydrogenation of trans-Chalcone Derivatives Using BINOL-derived Boro-phosphates
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Chiral phosphoric-acid-catalyzed asymmetric reductions of trans-chalcones have been investigated in this work. A BINOL-derived boro-phosphate-catalyzed asymmetric transfer hydrogenation of the carbon-carbon double bond of trans-chalcone derivatives employing borane as a hydride source was realized. This methodology provides a convenient procedure to access chiral dihydrochalone derivatives in high yields and with high enantioselectivities under mild conditions.
- Na, Fei,Lopez, Susana S.,Beauseigneur, Alice,Hernandez, Lucas W.,Sun, Zhuoxin,Antilla, Jon C.
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supporting information
p. 5953 - 5957
(2020/08/12)
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- Highly Selective and Catalytic Generation of Acyclic Quaternary Carbon Stereocenters via Functionalization of 1,3-Dienes with CO2
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The catalytic asymmetric functionalization of readily available 1,3-dienes is highly important, but current examples are mostly limited to the construction of tertiary chiral centers. The asymmetric generation of acyclic products containing all-carbon quaternary stereocenters from substituted 1,3-dienes represents a more challenging, but highly desirable, synthetic process for which there are very few examples. Herein, we report the highly selective copper-catalyzed generation of chiral all-carbon acyclic quaternary stereocenters via functionalization of 1,3-dienes with CO2. A variety of readily available 1,1-disubstituted 1,3-dienes, as well as a 1,3,5-triene, undergo reductive hydroxymethylation with high chemo-, regio-, E/Z-, and enantioselectivities. The reported method features good functional group tolerance, is readily scaled up to at least 5 mmol of starting diene, and generates chiral products that are useful building blocks for further derivatization. Systemic mechanistic investigations using density functional theory calculations were performed and provided the first theoretical investigation for an asymmetric transformation involving CO2. These computational results indicate that the 1,2-hydrocupration of 1,3-diene proceeds with high π-facial selectivity to generate an (S)-allylcopper intermediate, which further induces the chirality of the quaternary carbon center in the final product. The 1,4-addition of an internal allylcopper complex, which differs from previous reports involving terminal allylmetallic intermediates, to CO2 kinetically determines the E/Z- and regioselectivity. The rapid reduction of a copper carboxylate intermediate to the corresponding silyl-ether in the presence of Me(MeO)2SiH provides the exergonic impetus and leads to chemoselective hydroxymethylation rather than carboxylation. These results provide new insights for guiding further development of asymmetric C-C bond formations with CO2
- Chen, Xiao-Wang,Zhu, Lei,Gui, Yong-Yuan,Jing, Ke,Jiang, Yuan-Xu,Bo, Zhi-Yu,Lan, Yu,Li, Jing,Yu, Da-Gang
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p. 18825 - 18835
(2019/11/28)
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- Enantioselective epoxidation of β,β-disubstituted enamides with a manganese catalyst and aqueous hydrogen peroxide
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Enantioselective epoxidation of β,β-disubstituted enamides with aqueous hydrogen peroxide and a novel manganese catalyst is described. Epoxidation is stereospecific and proceeds fast under mild conditions. Amides are disclosed as key functional groups to enable high enantioselectivity.
- Clarasó, Carlota,Vicens, Laia,Polo, Alfonso,Costas, Miquel
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supporting information
p. 2430 - 2435
(2019/03/29)
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- Spatiotemporal Control of Pre-existing Alkene Geometry: A Bio-Inspired Route to 4-Trifluoromethyl-2H-chromenes
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Routes to prepare C4-trifluoromethyl analogues of the 2H-chromene scaffold are scarce: this is particularly striking given the importance of fluorine in pharmaceutical development. To address this limitation, a facile strategy has been developed that is reliant on catalytic, geometric isomerization of easily accessible allylic alcohols (up to >95:5) followed by intramolecular cyclization via Pd catalysis (up to 96%). This concise biomimetic approach emulates the photoisomerization/cyclization cascade inherent to phenylpropanoid biosynthesis.
- Fa?bender, Svenja I.,Metternich, Jan B.,Gilmour, Ryan
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supporting information
p. 724 - 727
(2018/02/09)
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- Rh-Catalyzed Asymmetric Hydrogenation of β-Branched Enol Esters for the Synthesis of β-Chiral Primary Alcohols
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An asymmetric hydrogenation of β-branched enol esters has been developed for the first time, providing a new route for the synthesis of β-chiral primary alcohols. Using a (S)-SKP-Rh complex bearing a large bite angle and enol ester substrates possessing an O-fomyl directing group, the desired products were obtained in quantitative yields and with excellent enantioselectivities.
- Liu, Chong,Yuan, Jing,Zhang, Jian,Wang, Zhihui,Zhang, Zhenfeng,Zhang, Wanbin
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supporting information
p. 108 - 111
(2018/01/17)
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- Transition-Metal-Free Formylation of Allylzinc Reagents Leading to α-Quaternary Aldehydes
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The first example of formylation of allylzinc reagents using S-phenyl thioformate is presented. The reaction proceeded under mild conditions without any transition-metal catalyst, forming quaternary carbon centers with reactive functionalities, such as formyl and vinyl groups. Moreover, Barbier-type formylation of an allylic bromide with a sterically demanding thioformate was achieved. As a preliminary result, asymmetric formylation was conducted using a menthol-derived chiral thioformate.
- Haraguchi, Ryosuke,Kusakabe, Akinori,Mizutani, Nakaba,Fukuzawa, Shin-Ichi
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supporting information
p. 1613 - 1616
(2018/03/23)
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- Copper(i)-catalysed asymmetric allylic reductions with hydrosilanes
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A copper(i)-catalysed asymmetric allylic reduction enables a regio- and stereoselective transfer of a hydride nucleophile in an SN2′-fashion onto allylic bromides. This transformation represents a conceptually orthogonal approach to allylic substitution reactions with carbon nucleophiles. A copper(i) complex based upon a chiral N-heterocyclic carbene (NHC) ligand allows for stereoselectivity reaching 99% ee. The catalyst enables a stereoconvergent reaction irrespective of the double bond configuration of the starting materials.
- Thanh Nguyen,Thiel, Niklas O.,Teichert, Johannes F.
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supporting information
p. 11686 - 11689
(2017/11/03)
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- Pd(II)/Bipyridine-Catalyzed Conjugate Addition of Arylboronic Acids to α,β-Unsaturated Carboxylic Acids. Synthesis of β-Quaternary Carbons Substituted Carboxylic Acids
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Pd(II)/bipyridine-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated carboxylic acids (including β,β-disubstituted acrylic acids) was developed and optimized, which provided a mild and convenient method for the highly challenging synthesis of β-quaternary carbons substituted carboxylic acids.
- Liu, Rui,Yang, Zhenyu,Ni, Yuxin,Song, Kaixuan,Shen, Kai,Lin, Shaohui,Pan, Qinmin
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p. 8023 - 8030
(2017/08/14)
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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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- A Bio-Inspired, Catalytic e → Z Isomerization of Activated Olefins
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Herein, Natures flavin-mediated activation of complex (poly)enes has been translated to a small molecule paradigm culminating in a highly (Z)-selective, catalytic isomerization of activated olefins using (-)-riboflavin (up to 99:1 Z/E). In contrast to the prominent Z → E isomerization of the natural system, it was possible to invert the directionality of the isomerization (E → Z) by simultaneously truncating the retinal scaffold, and introducing a third olefin substituent to augment A1,3-strain upon isomerization. Consequently, conjugation is reduced in the product chromophore leading to a substrate/product combination with discrete photophysical signatures. The operationally simple isomerization protocol has been applied to a variety of enone-derived substrates and showcased in the preparation of the medically relevant 4-substituted coumarin scaffold. A correlation of sensitizer triplet energy (ET) and reaction efficiency, together with the study of additive effects and mechanistic probes, is consistent with a triplet energy transfer mechanism.
- Metternich, Jan B.,Gilmour, Ryan
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supporting information
p. 11254 - 11257
(2015/09/21)
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- Enantioselective halogenative semi-pinacol rearrangement: A stereodivergent reaction on a racemic mixture
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An efficient, quantitative deracemization strategy for optically inactive allylic cycloalkanols has been achieved using the biphasic halogenative semi-pinacol reaction protocol. The resultant β-halo spiroketones, containing three contiguous stereogenic ce
- Romanov-Michailidis, Fedor,Pupier, Marion,Gune, Laure,Alexakis, Alexandre
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supporting information
p. 13461 - 13464
(2015/02/19)
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- Highly enantioselective hydrogenation of steric hindrance enones catalyzed by Ru complexes with chiral diamine and achiral phosphane
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An asymmetric hydrogenation of sterically hindered β,β- disubstituted enones has been well-established by using a ruthenium complex composed of an achiral diphosphane and a chiral diamine as catalyst, wherein the carbonyl group was selectively hydrogenated to give a wide range of chiral allylic alcohols with high levels of enantioselectivity and complete chemoselectivity.
- Chen, Xiangning,Zhou, Han,Zhang, Kunyu,Li, Jiawen,Huang, Hanmin
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supporting information
p. 3912 - 3915
(2014/08/18)
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- Superacid-promoted dual C-C bond formation by Friedel-Crafts alkylation and acylation of ethyl cinnamates: Synthesis of indanones
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A superacid (triflic acid) promoted dual C-C bond formation via intermolecular Friedel-Crafts alkylation (Michael addition type) and intramolecular acylation for the efficient synthesis of 3-substituted indan-1-ones is presented. This method was successful in activating ethyl cinnamates towards dual aromatic electrophilic substitution. Moreover, it enabled us to synthesize novel spirotetracyclic systems. Georg Thieme Verlag Stuttgart · New York.
- Venkat Ramulu, Bokka,Gopi Krishna Reddy, Alavala,Satyanarayana, Gedu
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p. 868 - 872
(2013/05/22)
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- Highly enantioselective asymmetric hydrogenation of (E)-β,β- disubstituted α,β-unsaturated Weinreb amides catalyzed by Ir(i) complexes of SpinPhox ligands
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The Ir(i) complexes of chiral spiro phosphino-oxazoline ligands (SpinPhox) have demonstrated good to excellent enantioselectivity in the asymmetric hydrogenation (AH) of a variety of (E)-β,β-disubstituted α,β-unsaturated N-methoxy-N-methylamides, affording the corresponding optically active Weinreb amides with up to 97% ee.
- Shang, Jian,Han, Zhaobin,Li, Yang,Wang, Zheng,Ding, Kuiling
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supporting information; experimental part
p. 5172 - 5174
(2012/06/18)
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- Highly enantioselective iridium-catalyzed hydrogenation of α,β-unsaturated esters
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α,β-Unsaturated esters have been employed as substrates in iridium-catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic- and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural products and pharmaceuticals. Asymmetric hydrogenation: A variety of α,β-unsaturated esters were hydrogenated with high enantioselectivities (see scheme). The hydrogenated products have been used in synthetic transformations as well as in formal total syntheses. Copyright
- Li, Jia-Qi,Quan, Xu,Andersson, Pher G.
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supporting information
p. 10609 - 10616
(2012/11/07)
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- Highly enantioselective asymmetric isomerization of primary allylic alcohols with an iridium-N,P complex
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Access to chiral aldehydes: The asymmetric isomerization of primary allylic alcohols was studied with a bicyclic phosphine-oxazoline iridium catalyst. This method displays a broad substrate scope and leads to the desired chiral aldehydes with excellent enantioselectivities (see scheme; R1, R 2=Ar or alkyl). Copyright
- Li, Jia-Qi,Peters, Byron,Andersson, Pher G.
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supporting information; experimental part
p. 11143 - 11145
(2011/10/31)
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- Pd-catalyzed asymmetric hydrogenation of C=C bond of α,β- unsaturated ketones
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Homogenous palladium-catalyzed asymmetric hydrogenation of C=C double bond of ,-unsaturated ketones has been -developed by using palladium(II) trifluoroacetate/(S)-7,7-bis-[di(4-methoxyphenyl]phosphino)-1,1-spirobiindane complex [Pd(OCOCF3)2-(S)-An-SDP] as the catalyst under ambient hydrogen pressure and room temperature with up to 89% ee. Georg Thieme Verlag Stuttgart · New York.
- Wang, Duo-Sheng,Wang, Da-Wei,Zhou, Yong-Gui
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supporting information; experimental part
p. 947 - 950
(2011/06/17)
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- Iron-catalyzed asymmetric epoxidation of β,β-disubstituted enones
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The combination of Fe(OTf)2 and novel phenanthroline ligands enables the catalytic asymmetric epoxidation of acyclic β,β- disubstituted enones, which have been a heretofore inaccessible substrate class. The reaction provides highly enantioenriched α,β-epoxyketones (up to 92% ee) that can be further converted to functionalized β-ketoaldehydes with an all-carbon quaternary center.
- Nishikawa, Yasuhiro,Yamamoto, Hisashi
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supporting information; experimental part
p. 8432 - 8435
(2011/07/29)
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- Enantioselective synthesis of allylboronates bearing a tertiary or quaternary B-substituted stereogenic carbon by NHC-Cu-catalyzed substitution reactions
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Allylic substitutions that afford α-substituted allylboronates bearing B-substituted tertiary or quaternary carbon stereogenic centers are presented. C-B bond-forming reactions, catalyzed by chiral bidentate Cu-NHC complexes, are performed in the presence of commercially available bis(pinacolato)diboron. Transformations proceed in high yield (up to >98%) and site selectivity (>98% SN2′), and in up to >99:1 enantiomer ratio. Trans- or cis-disubstituted alkenes can be used; alkyl- (linear as well as branched) and aryl-trisubstituted allylic carbonates serve as effective substrates. Allylboronates that bear a quaternary carbon center are air-stable and can be easily purified by silica gel chromatography; in contrast, secondary allylboronates cannot be purified in the same manner and are significantly less stable. Oxidation of the enantiomerically enriched products furnishes secondary or tertiary allylic alcohols, valuable small molecules that cannot be easily obtained in high enantiomeric purity by alternative synthesis or kinetic resolution approaches.
- Guzman-Martinez, Aikomari,Hoveyda, Amir H.
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supporting information; scheme or table
p. 10634 - 10637
(2010/11/05)
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- Improved catalysts for the iridium-catalyzed asymmetric isomerization of primary allylic alcohols based on charton analysis
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An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes that were not accessible previously have been obtained with high levels of enantioselectivity, thus validating the initial hypothesis regarding the selected ligand-design elements. A rationale for the high enantioselectivities achieved in most cases is also presented. Achieving enantioselectivity: An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relies on preliminary mechanistic information and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation (see figure).
- Mantilli, Luca,Gerard, David,Torche, Sonya,Besnard, Celine,Mazet, Clement
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supporting information; experimental part
p. 12736 - 12745
(2011/02/21)
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- Iridium-catalyzed asymmetric isomerization of primary allylic alcohols
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Nothing to sm(Ir)k at: Under appropriate reaction conditions, iridium hydride catalysts promote the isomerization of primary allylic alcohols. The best catalysts, like (R)-1 (P green, O red, N blue, Ir yellow), deliver the desired chiral aldehydes with excellent enantioselectivity and good yields. Mechanistic hypotheses have been developed on the basis of preliminary investigations.
- Mantilli, Luca,Gerard, David,Torche, Sonya,Besnard, Celine,Mazet, Clement
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supporting information; experimental part
p. 5143 - 5147
(2009/12/07)
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- Highly chemo- And enantioselective hydrogenation of linear α,β-unsaturated ketones
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A study was conducted to report the synthesis of sulfoximine-derived P,N-ligands and their applications in indium-catalyzed asymmetric hydrogenation reactions. Investigations were conducted using linear β,β- disubstituted 1,3-diphenyl-2-butenone as model substrate and iridium, having a ketonic phenyl group and two alkyl substituents at the olefinic β-positions. Methyl ketone with β-methyl and β-phenyl substituent was also applied in the investigations.
- Lu, Sheng-Mei,Bolm, Carsten
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supporting information; experimental part
p. 7513 - 7516
(2009/09/06)
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- Conjugate reduction of α,β-unsaturated carbonyl compounds catalyzed by a copper carbene complex
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(Matrix presented) An N-heterocyclic carbene copper chloride (NHC-CuCl) complex (2) has been prepared and used to catalyze the conjugate reduction of α,β-unsaturated carbonyl compounds. The combination of catalytic amounts of 2 and NaOt-Bu with poly(methy
- Jurkauskas, Valdas,Sadighi, Joseph P.,Buchwald, Stephen L.
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p. 2417 - 2420
(2007/10/03)
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- Novel syntheses of α,β-unsaturated esters, α,β-unsaturated γ-lactones, and 2-alkoxypyrroles via 1,2,4-triazole-stabilized allenic anions
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The dianion 12 (?13) of 1-(1,2,4-triazol-1-yl)phenylpropargyl ethyl ether 11 (readily prepared from phenylpropargylaldehyde diethyl acetal 8 and 1,2,4-triazole) reacts with alkyl halides, aldehydes, ketones, and α,β-unsaturated ketones to give exclusively γ-substituted allenic products of type 10. These adducts underwent mild in situ hydrolysis enabling convenient syntheses of α,β-unsaturated esters 9a-c and α,β-unsaturated γ-lactones 16, 18, 20, and 22. Reactions of dianion 13 with imines generated the 1,3,4-trisubstituted 2-alkoxypyrroles 27, 30, and 31 in high yields. The alkylsubstituted analog 34 underwent similar reactions to give predominantly the γ-products 39, 40, and 42 along with a small proportion of α-analogs.
- Katritzky, Alan R.,Feng, Darning,Lang, Hengyuan
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p. 715 - 720
(2007/10/03)
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- New reaction mode of the Horner-Wadsworth-Emmons reaction using Sn(OSO2CF3)2 and N-ethylpiperidine
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Excellent Z or E selectivity is observed in the Horner-Wadsworth-Emmons reactions of methyl bis(trifluoroethyl)phosphonoacetate 2 with aryl alkyl ketones 3a-d or aldehydes 3f,g using Sn(OSO2CF3)2 in the presence of N-ethylpiperidine, which should have a different reaction mode to those using sodium hydride.
- Sano, Shigeki,Yokoyama, Kenji,Fukushima, Mari,Yagi, Tetsuo,Nagao, Yoshimitsu
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p. 559 - 560
(2007/10/03)
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- Stereoselective synthesis of 3-alkylcinnamic esters via coupling reaction of (2Z)-3-(aryltelluro) cinnamic esters in presence of CuI
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Coupling reaction of (2Z)-3-(aryltelluro) cinnamic esters with Grignard reagents in presence of CuI produced trisubstituted alkenes containing ester groups with retention of configuration.
- Huang, Xian,Zhao, Chang-Qiu
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p. 237 - 241
(2007/10/03)
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- Stereoselective coupling reaction of (2Z)-β-arylselenocinnamic esters with Grignard reagents in presence of CuI
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Stereoselective synthesis of trisubstituted alkenes linked with ester groups via coupling reaction of (2Z)-β-arylselenocinnamic esters with Grignard reagents in presence of Equal molar quantities of CuI was reported.
- Huang, Xian,Zhao, Chang-Qiu
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p. 3491 - 3495
(2007/10/03)
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- Mechanism of Formation of α,β-Unsaturated Esters in the Reaction of Ethyl Mercaptoacetate Dianion with Carbonyl Compounds
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Dianion derived fron ethyl mercaptoacetate undergoes aldol type reaction with a carbonyl compounds to give an adduct, which exhibited low diastereoselectivity.However, the adducts obtained by the reaction with a variety of aldehydes were subsequently treated with ethyl chloroformate in the presence of trivalent phosphorus compound to give (E)-isomers of α,β-unsaturated esters in high yields with greater than 85percent stereoselectivity regardless of the stereochemistry of the diastereomers of the adducts.The stereochemical mechanism and application of this reaction were studied in detail.
- Matsui, Syuichi
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p. 426 - 434
(2007/10/02)
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- Stereochemistry of the Reactions of CuI Catalyzed Grignard Reagents with Ethyl (E)- and (Z)-β-Chlorocinnamates
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Ethyl (E)- and (Z)-3-chloro-3-phenyl-2-propenoate were prepared and separated.The (Z)-isomer gave β-alkylated ethyl cinnamates in good yield when reacted with alkyl Grignard reagents in the presence of 10percent CuI.The (Z)-isomer reacted with retention o
- Jalander, Lars,Broms, Merete
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p. 173 - 178
(2007/10/02)
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