- Asymmetric allylation of aldehydes with chiral platinum phosphinite complexes
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Platinum phosphinite complexes made from chiral diols catalyze the enantioselective allylation of cinnamaldehyde. This reaction proceeds with better yields at shorter reaction times in the presence of acetic acid. Enantiomeric excesses were greater when r
- Sharma, Rakesh K.,Samuelson, Ashoka G.
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- Stereoselective synthesis of cryptomoscatone D2
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Cryptomoscatone D2 was synthesized stereoselectively from trans-cinnamaldehyde. The synthesis of the triol frame work relied on the creations of the stereocenters independently by utilizing double Maruoka allylations and Sharpless epoxidation. The lactone
- Raju, Atla,Sabitha, Gowravaram
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Read Online
- Catalytic Asymmetric Allylation (CAA) reactions. II. A new enantioselective allylation procedure
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A simplified and highly efficient new protocol is described for asymmetric allylation of aldehydes using allyltri-n-butylstannane and a chiral Lewis acid.
- Keck, Gary E.,Geraci, Leo S.
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Read Online
- Bi(cyclopentyl)diol-Derived Boronates in Highly Enantioselective Chiral Phosphoric Acid-Catalyzed Allylation, Propargylation, and Crotylation of Aldehydes
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In this study, we disclose the catalytic addition of bi(cyclopentyl)diol-derived boronates to aldehydes promoted by chiral phosphoric acids, allowing for the formation of enantioenriched homoallylic, propargylic, and crotylic alcohols (up to >99% enantiom
- Yuan, Jinping,Jain, Pankaj,Antilla, Jon C.
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p. 12988 - 13003
(2020/11/23)
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- 3,3′-Bithiophene-Based Chiral Bisphosphine Oxides as Organocatalysts in Silicon-Derived Lewis Acid Mediated Reactions
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This account summarizes the development of new biheteroaromatic chiral bisphosphine oxides. 3,3′-Bithiophene-based phosphine oxides (BITIOPOs) have been successfully used as organocatalysts to promote Lewis base catalyzed, Lewis acid mediated stereoselective transformations. These highly electron-rich compounds, in combination with trichorosilyl derivatives (allyltrichlorosilane and silicon tetrachloride), generate hypervalent silicon species that act as chiral Lewis acids in highly diastereo- and enantioselective organic reactions. Several relevant examples related to these applications are discussed in detail. 1 Introduction 2 The BITIOPO Family 3 Enantioselective Opening of Epoxides 4 Enantioselective Allylation of Aldehydes 5 Stereoselective Direct (Double) Aldol-Type Reaction with Ketones 6 Stereoselective Direct Aldol-Type Reaction with Ester Derivatives 7 Conclusions.
- Benaglia, Maurizio,Benincori, Tiziana,Raimondi, Laura Maria,Rossi, Sergio
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p. 535 - 546
(2020/03/27)
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- Axially chiral N,N′-dioxides ethers for catalysis in enantioselective allylation of aldehydes
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A series of axially chiral ethers synthesized from biscarboline N,N′-dioxides, (S)-1a to (S)-1n, was investigated in enantioselectivity addition reactions of allyltrichlorosilane with a series of substituted aldehydes, including bulky substituted aldehydes. High enantioselectivities (up to 96%ee) were achieved using the catalyst (S)-1k at 1 mol % loading.
- Wu, Shijie,Xing, Yongfei,Wang, Jie,Guo, Xingchen,Zhu, Huajie,Li, Wan
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supporting information
p. 947 - 957
(2019/08/30)
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- TetraPh-Tol-BITIOPO: A new atropisomeric 3,3′-bithiophene based phosphine oxide as an organocatalyst in Lewis base-catalyzed Lewis acid mediated reactions
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A new chiral phosphine oxide based on a 3,3′-bithiophene scaffold (TetraPh-Tol-BITIOPO) was synthesized, fully characterized and separated into antipodes through chiral HPLC. This new compound was successfully employed as an organocatalyst in Lewis base-catalyzed Lewis acid mediated reactions involving trichlorosilyl compounds. The new atropisomeric catalyst was able to promote the allylation of aldehydes with allyltrichlorosilane in up to 98% yield and up to 96% enantiomeric excess (ee), and the direct aldol reaction to afford β-hydroxy ketones and β-hydroxy thioesters, with good chemical yields and modest stereochemical efficiency. Computational studies helped to elucidate and to rationalize the stereochemical outcome of the reactions catalyzed by TetraPh-Tol-BITIOPO that was found to favour the formation of the isomer with an opposite absolute configuration in comparison with the products obtained with the previously reported 3,3′-bithiophene-based catalyst.
- Mirco, Abbinante Vincenzo,Maurizio, Benaglia,Sergio, Rossi,Tiziana, Benincori,Roberto, Cirilli,Marco, Pierini
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supporting information
p. 7474 - 7481
(2019/08/20)
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- Axial-Chiral Biisoquinoline N, N′-Dioxides Bearing Polar Aromatic C-H Bonds as Catalysts in Sakurai-Hosomi-Denmark Allylation
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The design, synthesis, and evaluation of axial-chiral biisoquinolines bearing polar aromatic C-H bonds as Lewis base catalysts are reported. Lewis bases containing the 3,5-bis(trifluoromethyl)phenyl group were found to be significantly more enantioselecti
- Reep, Carlyn,Morgante, Pierpaolo,Peverati, Roberto,Takenaka, Norito
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supporting information
p. 5757 - 5761
(2018/09/29)
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- Chiral Unsymmetrically Substituted Bipyridine N,N′-Dioxides as Catalysts for the Allylation of Aldehydes
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A series of unsymmetrically substituted diastereoisomeric (Ra,R) and (Sa,R) bipyridine N,N′-dioxides was synthesized by using oxidative coupling of the corresponding metallated tetrahydroisoquinoline N-oxides in the presence of iodin
- Ul?, Jan,Ne?as, David,Koukal, Petr,Havlí?ek, Vojtěch,To?ner, Zdeněk,Hybelbauerová, Simona,Kotora, Martin
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supporting information
p. 5109 - 5116
(2018/07/31)
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- Enantioselective Allyl-, and Allenylboration of Aldehydes Catalyzed by Chiral Hydroxyl Carboxylic Acid
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Asymmetric allylboration of aldehydes with allylboronic acid pinacol ester catalyzed by chiral hydroxyl carboxylic acid is described. This reaction provides synthetically useful homoallyl alcohols in high yield with good to high enantioselectivity. The pr
- Ota, Yuya,Kawato, Yuji,Egami, Hiromichi,Hamashima, Yoshitaka
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supporting information
p. 976 - 980
(2017/05/05)
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- First total synthesis of the highly potent antitumor lactones 8-chlorogoniodiol and parvistone A: Exploiting a bioinspired late-stage epoxide ring-opening
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The first protecting group-free total syntheses of the highly potent antitumor chlorinated styryllactone secondary metabolites 8-chlorogoniodiol, parvistone A, and one analogue 8-epi-parvistone A, have been accomplished from commercially available trans-cinnamaldehyde in five steps with high overall yields. The chlorine-bearing stereogenic center of these silent secondary metabolites was introduced via a bioinspired late-stage regioselective epoxide ring-opening strategy. Maruoka asymmetric allylation, acrylation, ring-closing metathesis and asymmetric epoxidation, greatly facilitate the synthesis of the key intermediates goniothalamin oxide and (6S,7S,8S)-isogoniothalamin oxide.
- Ramesh, Perla,Narasimha Reddy, Yarram,Narendar Reddy, Thatikonda,Srinivasu, Navuluri
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supporting information
p. 246 - 249
(2017/02/15)
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- Asymmetric Allylation of Carbonyl Compounds Catalyzed by a Chiral Phosphine–Silver Complex
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A catalytic, asymmetric allylation reaction of aldehydes or ketones with allyltrimethoxysilane was achieved by using a BINAP·AgBF4 [BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl] complex as the chiral precatalyst and triethylamine as the
- Yanagisawa, Akira,Yang, Nan,Bamba, Kentaro
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supporting information
p. 6614 - 6618
(2017/12/15)
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- Accessing Both Retention and Inversion Pathways in Stereospecific, Nickel-Catalyzed Miyaura Borylations of Allylic Pivalates
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We have developed a stereospecific, nickel-catalyzed Miyaura borylation of allylic pivalates, which delivers highly enantioenriched α-stereogenic γ-aryl allylboronates with good yields and regioselectivities. Our complementary sets of conditions enable access to either enantiomer of allylboronate product from a single enantiomer of readily prepared allylic pivalate substrate. Excellent functional group tolerance, yields, regioselectivities, and stereochemical fidelities are observed. The stereochemical switch from stereoretention to stereoinversion largely depends upon solvent and can be explained by competitive pathways for the oxidative addition step. Our mechanistic investigations support a stereoretentive pathway stemming from a directed oxidative addition and a stereoinvertive pathway that is dominant when MeCN blocks coordination of the directing group by binding the nickel catalyst.
- Zhou, Qi,Srinivas, Harathi D.,Zhang, Songnan,Watson, Mary P.
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p. 11989 - 11995
(2016/10/07)
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- Polystyrene-Supported TRIP: A highly recyclable catalyst for batch and flow enantioselective allylation of aldehydes
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The widely applicable TRIP phosphoric acid catalyst has been immobilized on polystyrene using a copolymerization-based strategy. The resin (PS-TRIP) has proven to be highly active and enantioselective in the asymmetric allylboration of aldehydes. Moreover
- Clot-Almenara, Lidia,Rodríguez-Escrich, Carles,Osorio-Planes, Laura,Pericas, Miquel A.
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p. 7647 - 7651
(2018/05/23)
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- Extremely Active Organocatalysts Enable a Highly Enantioselective Addition of Allyltrimethylsilane to Aldehydes
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The enantioselective allylation of aldehydes to form homoallylic alcohols is one of the most frequently used carbon–carbon bond-forming reaction in chemical synthesis and, for several decades, has been a testing ground for new asymmetric methodology. Howe
- Kaib, Philip S. J.,Schreyer, Lucas,Lee, Sunggi,Properzi, Roberta,List, Benjamin
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supporting information
p. 13200 - 13203
(2016/10/30)
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- Biosynthesis-Inspired Total Synthesis of Bioactive Styryllactones (+)-Goniodiol, (6S,7S,8S)-Goniodiol, (-)-Parvistone D, and (+)-Parvistone e
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A protecting-group-free total synthesis of (+)-goniodiol (1), (6S,7S,8S)-goniodiol (2), (-)-parvistone D (4), and (+)-parvistone E (6) was efficiently achieved in five steps from commercially available trans-cinnamaldehyde with high overall yields (72-75%). The synthesis strategy was inspired from the proposed biosynthesis pathway of styryllactones. Key transformations of the strategy include a one-pot conversion of goniothalamin oxide to goniodiol or 9-deoxygoniopypyrone in aqueous media, stereoselective epoxidation, ring-closing metathesis, and stereoselective Maruoka allylation. The route is amenable to synthesis of various analogues for biological evaluation.
- Ramesh, Perla,Rao, Tadikamalla P.
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p. 2060 - 2065
(2016/09/09)
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- Protecting-Group-Free Total Synthesis of 8-Methoxygoniodiol
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A concise stereoselective total synthesis of the naturally occurring styryl lactone 8-methoxygoniodiol in five simple steps from readily available inexpensive trans-cinnamaldehyde is described. The efficient synthesis features a successful protecting-group-free strategy, with desirable step- and atom-economy. The synthetic strategy relies on a Maruoka asymmetric allylation, an epoxidation, a ring-closing metathesis, and a stereoselective epoxide ring opening as key steps.
- Ramesh, Perla
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p. 4300 - 4304
(2016/11/26)
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- Total synthesis of cryptomoscatone F1 through an asymmetric aldol approach
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A stereoselective total synthesis of naturally occurring styryl lactone, cryptomoscatone F1 is described. A Mukaiyama asymmetric aldol reaction, Brown's asymmetric allylation, Maruoka asymmetric allylation, and cross metathesis were used as the key steps.
- Ramesh, Perla,Raju, Atla,Fadnavis, Nitin W.
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p. 1251 - 1255
(2015/11/09)
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- Oxazoline derivatives tagged with tosylated amino acids as recyclable organocatalysts for enantioselective allylation of aldehydes
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A series of amino acid-based oxazoline compounds have been prepared and successfully applied to the enantioselective allylation reaction of aldehydes. The fine-tuning of the structure of the oxazolines led to (S,S)-4 as an efficient organocatalyst which gave homoallyl alcohols in good yield (up to 90%) and excellent ee (up to 99%) for a wide range of substrates including aromatic, hetero-aromatic and α,β-unsaturated aldehydes. The chiral organocatalyst was synthesized in three easy steps with an overall 88% yield and successfully recycled for up to three cycles. On the basis of the experimental observations and NMR studies, a probable mechanism was proposed for this reaction.
- Ghosh, Debashis,Sadhukhan, Arghya,Maity, Nabin Ch.,Abdi, Sayed H. R.,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Bajaj, Hari C.
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p. 12257 - 12265
(2014/03/21)
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- Br?nsted acid-catalyzed asymmetric allylation and propargylation of aldehydes
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A method synthesizing homoallylic or homopropargylic alcohols was developed to react aldehydes with allyl boronates, such as allylboronic acid pinacol ester, or allenylborates in the presence of a catalytic amount of a chiral binaphthyl-derived chiral pho
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Page/Page column 8; 19; 20
(2013/08/28)
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- Stereospecific allyl-aryl coupling catalyzed by in situ generated palladium nanoparticles in water under ambient conditions
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A practical process for the stereospecific cross-coupling of secondary allylic carbonates with arylboronic acids has been developed. The reaction is catalyzed by in situ generated palladium nanoparticles (PdNPs) without any ligands and additional stabilizers in water under ambient conditions and furnishes the allyl-aryl coupling products in high isolated yields with high stereospecificities as well as excellent chemo-, regio- and E/Z-selectivities. The in situ generated PdNPs showed extraordinary catalytic activity (S/C up to 5000) even for the allyl-aryl coupling reactions of easily eliminated allylic carbonates under aqueous ambient conditions. The mechanism of the process has also been investigated.
- Zhao, Jingming,Ye, Jiang,Zhang, Yong Jian
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supporting information
p. 491 - 498
(2013/05/09)
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- Synthetically amenable amide derivatives of tosylated-amino acids as organocatalysts for enantioselective allylation of aldehydes: Computational rationale for enantioselectivity
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A phenylalanine derived chiral amide is developed that serves as an effective organocatalyst for the reaction of allyltrichlorosilane with aryl, hetero-aryl and α,β-unsaturated aldehydes to afford the desired homoallylic alcohols in good yield (up to 90%)
- Ghosh, Debashis,Sahu, Debashis,Saravanan,Abdi, Sayed H. R.,Ganguly, Bishwajit,Khan, Noor-Ul H.,Kureshy, Rukhsana I.,Bajaj, Hari C.
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supporting information
p. 3451 - 3460
(2013/06/05)
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- Chiral bis(imidazolinyl)phenyl NCN pincer rhodium(III) Catalysts for enantioselective allylation of aldehydes and carbonyl-ene reaction of trifluoropyruvates
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Chiral NCN pincer rhodium(III) complexes with bis(imidazolinyl)phenyl ligands were found to be effective catalysts for the allylation of a variety of electronically and structurally diverse aldehydes with allyltributyltin, giving the corresponding optical
- Wang, Tao,Hao, Xin-Qi,Huang, Juan-Juan,Niu, Jun-Long,Gong, Jun-Fang,Song, Mao-Ping
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p. 8712 - 8721
(2013/09/24)
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- Consecutive iridium catalyzed C-C and C-H bond forming hydrogenations for the diastereo- and enantioselective synthesis of syn-3-fluoro-1-alcohols: C-H (2-fluoro)allylation of primary alcohols
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Commercially available (2-fluoro)allyl chloride serves as an efficient allyl donor in highly enantioselective iridium catalyzed carbonyl (2-fluoro)allylations from the alcohol or aldehyde oxidation level via transfer hydrogenation. Diastereoselective Crab
- Hassan, Abbas,Montgomery, T. Patrick,Krische, Michael J.
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supporting information; experimental part
p. 4692 - 4694
(2012/06/01)
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- Conformationally rigid chiral pyridine N-oxides as organocatalyst: Asymmetric allylation of aldehydes
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A pyridine unit with a conformationally rigid chiral backbone has been designed and synthesized in an enantiomerically pure form to utilize in the Lewis base-catalyzed Sakurai-Hosomi-Denmark-type allylation reaction. The chiral pyridine N-oxide in 1:1 mix
- Gnanamani, Elumalai,Someshwar, Nagamalla,Ramanathan, Chinnasamy Ramaraj
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supporting information
p. 2101 - 2106
(2012/11/07)
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- Asymmetric allylboration of aldehydes with pinacol allylboronates catalyzed by 1,1′-spirobiindane-7,7′-diol (SPINOL) based phosphoric acids
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The asymmetric allylboration of aldehydes with pinacolallylboronates catalyzed by 1,1′-spirobiindane-7,7′-diol (SPINOL) based phosphoric acids is described. 6,6′-Bis(2,4,6-triisopropylphenyl)SPINOL-based phosphoric acid was found to be a general, highly e
- Xing, Chun-Hui,Liao, Yuan-Xi,Zhang, Yimei,Sabarova, Darya,Bassous, Monica,Hu, Qiao-Sheng
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supporting information; experimental part
p. 1115 - 1118
(2012/04/10)
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- First example of hydrolytic kinetic resolution of acrylate of secondary alcohols by lipase Amano AK
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Lipase Amano AK is found to be extremely efficient catalyst for hydrolytic kinetic resolution of acrylates of secondary alcohols in aqueous phosphate buffer at pH 7.0. Both aliphatic and benzylic secondary alcohols show good to excellent E values.
- Bora, Pranjal P.,Bez, Ghanashyam,Anal, Jasha Momo H.
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experimental part
p. 270 - 275
(2012/07/03)
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- Sequencing cross-metathesis and non-metathesis reactions to rapidly access building blocks for synthesis
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The olefin cross-metathesis reaction has been sequenced with four common organic transformations in a one- or two-pot manner to rapidly access useful building blocks. Those reactions are: (1) phosphorus-based olefination (e.g., Wittig and Horner-Wadsworth-Emmons); (2) hydride reduction; (3) Evans propionate aldol reaction; (4) Brown allyl- and Roush crotyl-boration. The products of these reactions include stereodefined 2,4-dienoates, trans allylic alcohols, syn-propionate aldols, and chiral non-racemic homoallylic alcohols, respectively. Many of these intermediates have been carried further to natural products, demonstrating the utility of the methodology.
- Sirasani, Gopal,Paul, Tapas,Andrade, Rodrigo B.
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experimental part
p. 2197 - 2205
(2011/04/22)
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- Enantioselective allylation of α,β-unsaturated aldehydes with allyltrichlorosilane catalyzed by METHOX
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α,β-Unsaturated aldehydes 6a-j undergo an enantioselective allylation with allylic trichlorosilanes 2a,b in the presence of METHOX (4) as a Lewis basic catalyst (≤10 mol %) to produce the homoallylic alcohols 7a-l at good to high enantioselectivity (83-96% ee). This study shows that the reactivity scope of METHOX can be extended from aromatic to nonaromatic aldehydes.
- Malkov, Andrei V.,Barlog, MacIej,Jewkes, Yvonne,Mikusek, Jiri,Kocovsky, Pavel
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experimental part
p. 4800 - 4804
(2011/07/09)
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- Sulfoxides in the allylation of aldehydes in the presence of silicon tetrachloride and allyltributylstannane
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SiCl4 can be conveniently activated by catalytic amounts of dimethyl sulfoxide or other readily-available sulfoxides for the allylation of aromatic, hetero-aromatic and unsaturated aldehydes in the presence of allyltributyl stannane. Chiral ary
- Massa, Antonio,Capozzolo, Laura,Scettri, Arrigo
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experimental part
p. 1210 - 1215
(2011/12/15)
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- Asymmetrie allylation of aldehydes catalyzed by simple dual small organic molecules: L-proline and L-prolinol
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A novel and simple methodology for the asymmetric allylation of aldehydes was reported. Double small organic molecules such as L-proline and L-prolinol were first employed for providing a chiral environment so as to afford chiral homoallylic alcohols in high yields and moderate enantioselectivities in our protocol.
- Chen, Guo-Hong,Liu, Ling-Yan,Wei, Xiao-Ning,Chang, Wei-Xing,Li, Jing
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scheme or table
p. 1013 - 1015
(2011/01/06)
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- Chiral bronsted acid-catalyzed allylboration of aldehydes
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The catalytic enantioselective allylation of aldehydes is a long-standing problem of considerable interest to the chemical community. We disclose a new high-yielding and highly enantioselective chiral Bronsted acid-catalyzed allylboration of aldehydes. Th
- Jain, Pankaj,Antilla, Jon C.
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supporting information; experimental part
p. 11884 - 11886
(2010/11/17)
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- Lewis base catalyzed enantioselective allylation of α,β- unsaturated aldehydes
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Being selective: The catalytic allylation of, α,β-unsaturated aldehydes with allyltrichlorosilane in the presence of chiral 3,3′-unsymmetrically substituted bis(tetrahydroisoquinoline) N,N-dioxides was explored. The allylation of various aldehydes proceeded under mild reaction conditions (-78□ °C) with high yields and enantioselectivity (see scheme). This allylation was applied in the synthesis of (S)-(-)-goniothalamin.
- Kadlcikova, Aneta,Valterova, Irena,Duchackova, Lucie,Roithova, Jana,Kotora, Martin
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supporting information; experimental part
p. 9442 - 9445
(2010/11/04)
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- Enantioselective allylation of aldehydes catalyzed by diastereoisomeric bis(tetrahydroisoquinoline) N,N′-dioxides
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Enantioselective allylation of aromatic and α,β-unsaturated aldehydes with allyltrichlorosilane catalyzed by two diastereoisomeric (R,R ax,R)- and (R,Sax,R)-bis-1,1′-[5,6,7,8-tetrahydro-3- (tetrahydrofuran-2-yl)isoquinoline] N,N′-dio
- Vlasana, Klara,Hrdina, Radim,Valterova, Irena,Kotora, Martin
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supporting information; experimental part
p. 7040 - 7044
(2011/02/25)
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- De novo asymmetric syntheses of (+)-goniothalamin, (+)-goniothalamin oxide, and 7,8-bis-epi-goniothalamin using asymmetric allylations
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A highly enantio- and diastereoselective approach to either enantiomer of (+)-goniothalamin, (+)-goniothalamin oxide, and 7,8-bis-epi-goniothalamin oxide has been developed from achiral cinnamyl alcohol or cinnamaldehyde. The asymmetry of the synthesis wa
- Harsh, Philip,O'Doherty, George A.
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scheme or table
p. 5051 - 5055
(2009/12/01)
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- Aryl tert-butyl sulfoxide-promoted highly enantioselective addition of allyltrichlorosilane to aldehydes
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A series of enantiomerically pure mono- and bis-aryl tert-butyl sulfoxides were synthesised to promote the enantioselective allylation of aldehydes with allyltrichlorosilane. Moderate to good yields and modest to high enantioselectivities were achieved. The absence of nonlinear effect, spacer effect, promoter loading and concentration effect indicate that only one molecule of aryl tert-butyl sulfoxide is involved in the stereodetermining step.
- Wang, Peng,Chen, Junmin,Cun, Linfeng,Deng, Jingen,Zhu, Jin,Liao, Jian
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experimental part
p. 3741 - 3747
(2009/10/24)
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- Enantioselective iridium-catalyzed carbonyl allylation from the alcohol or aldehyde oxidation level via transfer hydrogenative coupling of allyl acetate: Departure from chirally modified allyl metal reagents in carbonyl addition
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Under the conditions of transfer hydrogenation employing an iridium catalyst generated in situ from [Ir(COd)Cl]2, chiral phosphine ligand (R)-BINAP or (R)-Cl,MeO-BIPHEP, and m-nitrobenzoic acid, allyl acetate couples to allylic alcohols 1a-c, aliphatic alcohols 1d-1, and benzylic alcohols 1m-u to furnish products of carbonyl allylation 3a-u with exceptional levels of asymmetric induction. The very same set of optically enriched carbonyl allylation products 3a-u are accessible from enals 2a-c, aliphatic aldehydes 2d-1, and aryl aldehydes 2m-u, using iridium catalysts ligated by (-)-TMBTP or (R)-Cl,MeO-BIPHEP under identical conditions, but employing isopropanol as a hydrogen donor. A catalytically active cyclometallated complex V, which arises upon ortho-C-H insertion of iridium onto m-nitrobenzoic acid, was characterized by single-crystal X-ray diffraction. The results of isotopic labeling are consistent with intervention of symmetric iridium π-allyl intermediates or rapid interconversion of σ-allyl haptomers through the agency of a symmetric π-allyl. Competition experiments demonstrate rapid and reversible hydrogenation-dehydrogenation of the carbonyl partner in advance of C-C coupling. However, the coupling products, which are homoallylic alcohols, experience very little erosion of optical purity by way of redox equilibration under the coupling conditions, although isopropanol, a secondary alcohol, may serve as terminal reductant. A plausible catalytic mechanism accounting for these observations is proposed, along with a stereochemical model that accounts for the observed sense of absolute stereoinduction. This protocol for asymmetric carbonyl allylation transcends the barriers imposed by oxidation level and the use of preformed allyl metal reagents.
- Kim, In Su,Ngai, Ming-Yu,Krische, Michael J.
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supporting information; experimental part
p. 14891 - 14899
(2009/02/08)
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- A concise enantioselective strategy to (+)-(R)-goniothalamin and (+)-(R)-goniothalamin oxide by employing hydrolytic kinetic resolution and ring-closing metathesis as key steps
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An efficient and general strategy to (R)-goniothalamin and (R)-goniothalamin oxide is described by using Jacobsen's hydrolytic kinetic resolution of racemic epoxide and ring-closing metathesis (RCM) as key steps, which provided a rapid access to these natural products that display a fascinating array of biological activity. (R)-Goniothalamin oxide was prepared in high yield and diastereomeric excess under various epoxidation conditions. Georg Thieme Verlag Stuttgart.
- Bose, D. Subhas,Reddy, A. V. Narsimha,Srikanth, Bingi
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body text
p. 2323 - 2326
(2009/04/04)
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- A new class of chiral lewis basic metal-free catalysts for stereoselective allylations of aldehydes
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A new class of amine N-oxides derived from trans-2,5-diphenylpyrrolidine were synthesized in enantiomerically pure form and tested as metal-free catalysts in the reaction of aldehydes with allyl(trichloro)silane to afford homoallylic alcohols. The products were obtained in fair to good yields and up to 85% ee. The behavior of structurally different catalysts and the influence of a coordinating unit present in the organocatalyst on controlling the stereochemical efficiency of the reaction were also investigated. Noteworthy a catalyst capable of promoting the allylation of aliphatic aldehydes with an almost unprecedent and unusually high enantioselectivity, up to 85%, was identified. Georg Thieme Verlag Stuttgart.
- Simonini, Valentina,Benaglia, Maurizio,Pignataro, Luca,Guizzetti, Stefania,Celentano, Giuseppe
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experimental part
p. 1061 - 1065
(2009/04/06)
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- Enantioselective allylation of aldehydes with allyltrichlorosilane promoted by new chiral dipyridylmethane N-oxides
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New chiral dipyridine N-monoxides and N,N′-dioxides, which possess an isopropylidene backbone between two pyridine rings, have been prepared from naturally occurring monoterpenes. Their utility as organocatalysts has been demonstrated in the enantioselect
- Chelucci, Giorgio,Belmonte, Nicola,Benaglia, Maurizio,Pignataro, Luca
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p. 4037 - 4041
(2008/02/04)
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- Enantioselective allylation of aldehydes catalyzed by new bifunctional bisoxazoline-metal complexes
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The asymmetric allylation reactions of aldehydes catalyzed by a 10 mol % bisoxazoline complex bearing a phosphine oxide moiety, which was newly designed and synthesized from l-serine, afforded the corresponding homoallylic alcohols in 48-74% yields with 3
- Takeuchi, Keiichi,Takeda, Takuma,Fujimoto, Tetsuya,Yamamoto, Iwao
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p. 5319 - 5322
(2008/02/02)
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- Catalytic asymmetric allylation of aldehydes using the chiral (salen)chromium(III) complexes
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The enantioselective addition of allylstannanes to glyoxylates and glyoxals, as well as simple aromatic and aliphatic aldehydes, catalyzed by chiral (salen)Cr(III) complexes, has been studied. The reaction proceeded smoothly for the reactive 2-oxoaldehydes and allyltributyltin in the presence of small amounts (1-2 mol %) of (salen)Cr(III)BF4 (1b) under mild, undemanding conditions. However, in the case of other simple aldehydes, the use of high-pressure conditions is required to obtain good yields. Classic chromium catalyst 1b, easily prepared from the commercially available chloride complex 1a, affords homoallylic alcohols usually in good yield and with enantiomeric purity of 50-79% ee. The stereochemical results are rationalized on the basis of the proposed model.
- Kwiatkowski, Piotr,Cha?adaj, Wojciech,Jurczak, Janusz
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p. 5116 - 5125
(2007/10/03)
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- Application of tridentate bis(oxazoline) ligands in catalytic asymmetric Nozaki-Hiyama allylation and crotylation: An example of high enantioselection with a non-symmetric bis(oxazoline) ligand
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A series of both symmetric and non-symmetric bis(oxazoline) ligands was applied in the Nozaki-Hiyama allylation and crotylation of benzaldehyde. It was found that both the magnitude and sense of the asymmetric induction depended strongly on the nature and
- McManus, Helen A.,Cozzi, Pier Giorgio,Guiry, Patrick J.
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p. 551 - 558
(2007/10/03)
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- Catalytic enantioselective and catalyst-controlled diastereofacial- selective additions of allyl- and crotylboronates to aldehydes using chiral Bronsted acids
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(Chemical Equation Presented) Towards the ideal: A chiral diol-SnCl 4 complex is applied to the allylboration of aldehydes (see scheme). This approach highlights the use of chiral Bronsted acid catalysis in the development of an ideal method for the allylation of aldehydes which would display high diastereo- and enantioselectivity, wide substrate scope, and high practicality (ease of use, low cost, and low environmental impact).
- Rauniyar, Vivek,Hall, Dennis G.
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p. 2426 - 2428
(2007/10/03)
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- Chiral phosphoramide-catalyzed enantioselective addition of allylic trichlorosilanes to aldehydes. Preparative studies with bidentate phosphorus-based amides
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On the basis of the mechanistic insight that more than one Lewis basic moiety (phosphoramide) is involved in the rate- and stereochemistry-determining step of enantioselective allylation, bidentate chiral phosphoramides were developed. Different chiral phosphoramide moieties were connected by tethers of methylene chains of varying length. The rate and enantioselectivity of allylation with allyltrichlorosilane promoted by the bidentate phosphoramides was found to be highly dependent on the tether length. A new phosphoramide based on a 2,2′-bispyrrolidine skeleton has been designed and afforded good yield, efficient turnover, and high enantioselectivity in allylation reactions. The synthesis of enantiopure 2,2′-bispyrrolidine was easily accomplished on large scale by photodimerization of pyrrolidine followed by resolution with L(or D)-tartaric acid. The scope of the allylation reaction was examined with variously substituted allylic trichlorosilanes and unsaturated aldehydes. This method has been applied to the construction of stereogenic, quaternary centers by the addition of unsymmetrically γ-disubstituted allylic trichlorosilanes.
- Denmark, Scott E.,Fu, Jiping,Lawler, Michael J.
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p. 1523 - 1536
(2007/10/03)
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- Asymmetric allylation of aldehydes with allyltrichlorosilane using aza-paracyclophane-oxazoline-N-oxide catalysts
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Novel aza-paracyclophane-oxazoline catalysts 4, 5 were produced from V?gtle's Rp-2-cyano-aza-paraclycophane and amino alcohols reacted with zinc chloride followed by m-chloroperbenzoic acid. 4′-Benzyl and tert-butyl-S and R-oxazoline variants w
- Chai, Qiang,Song, Chun,Sun, Zhijun,Ma, Yudao,Ma, Chanqin,Dai, Yong,Andrus, Merritt B.
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p. 8611 - 8615
(2007/10/03)
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- A sterically modified (salen)chromium(III) complex - An efficient catalyst for high-pressure asymmetric allylation of aldehydes
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A novel (salen)chromium(III) catalyst with a modified salen ligand was synthesised in a simple way starting from readily available precursors. High-pressure allylation reaction of aromatic and aliphatic aldehydes with allyltributyltin upon application of
- Kwiatkowski, Piotr,Cha?adaj, Wojciech,Jurczak, Janusz
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p. 2301 - 2304
(2007/10/03)
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- Stereochemical diversity in chiral ligand design: Discovery and optimization of catalysts for the enantioselective addition of allylic halides to aldehydes
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(Chemical Equation Presented) We have identified a new set of stereochemically diverse oxazoline ligands derived from simple amino acids that promote the Cr-catalyzed enantioselective addition of allylic halides to aldehydes in up to 95% ee. The Cr-cataly
- Lee, Jae-Young,Miller, Jeremie J.,Hamilton, Steven S.,Sigman, Matthew S.
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p. 1837 - 1839
(2007/10/03)
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- Asymmetric allyl- and crotylboration with the robust, versatile, and recyclable 10-TMS-9-borabicyclo[3.3.2]decanes
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The remarkable versatility and selectivity of the 10-(trimethylsilyl)-9- borabicyclo[3.3.2]decanes (10-TMS-9-BBDs) in the allyl- and crotylboration of representative aldehydes are reported. The new reagents are prepared through air-stable crystalline pseudoephedrine borinic ester complexes of the 10-TMS-9-BBDs (4), which are available in 63% overall yield from B-MeO-9-BBN through a simple two-step procedure. These complexes 4 are directly converted to the corresponding B-allyl-10-TMS-9-BBDs (1) with allylmagnesium bromide, which either can be isolated (98%) or used in situ for the allylations. The remarkable enantioselectivity (96 to ≥99% ee) of these reagents in the rapid (3 h), asymmetric allylboration process at -78 °C is only slightly diminished when it is conducted at 25 °C, a phenomenon attributable to its rigid bicyclic structure. In addition to providing the homoallylic alcohols 6 efficiently (68-80%), the procedure also permits the efficient recovery of 4 (68-84%) for the direct regeneration of 1. Alternatively, an oxidative workup procedure can be used for the preparation of 6. The reagent gives predictable stereochemistry and exhibits an extremely high level of reagent control in the allylboration of D-glyceraldehyde acetonide. A simple and efficient procedure has been developed for the preparation of all four geometric and enantiomeric isomers of the B-crotyl-10-TMS-9-BBDs (10) from optically pure enantiomers of B-MeO-10-TMS-9-BBD (3). These reagents 10 also add rapidly (3 h) and efficiently to representative aldehydes at -78 °C, providing ready access to all four of the possible stereoisomers of the β-methyl homoallylic alcohols 12-15 (69-92%) in high dr (≥98:2) and ee (94-99%).
- Burgos, Carlos H.,Canales, Eda,Matos, Karl,Soderquist, John A.
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p. 8044 - 8049
(2007/10/03)
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- Highly enantioselective allylation of aldehydes catalyzed by indium(III) - PYBOX complex
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(Chemical Equation Presented) A chiral indium(III) - PYBOX complex prepared from indium triflate and chiral PYBOX has been discovered to effect high enantioselectivities in the addition of allyltributyl stannane to aldehydes. The allylation of a variety of aromatic, α,β-unsaturated, and aliphatic aldehydes resulted in good yields and high enantioselectivities (up to 94% ee).
- Lu, Jun,Ji, Shun-Jun,Teo, Yong-Chua,Loh, Teck-Peng
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p. 159 - 161
(2007/10/03)
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- (R)-Goniothalamin: Total syntheses and cytotoxic activity against cancer cell lines
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The total syntheses of (R)-goniothalamin (1), a styryl lactone isolated from several Goniothalamus species, via catalytic asymmetric allylation of α-benzyloxyacetaldehyde (2), followed by ring-closing metathesis and Wittig olefination and via catalytic asymmetric allylation of trans-cinnamaldehyde (12), followed by ring-closing metathesis are reported. The antiproliferative activities of (R)-1 and its Z-isomer 10 as well as of the synthetic dihydropyranone intermediates 7 and 8 against eight different cancer cell lines are also described.
- De Fatima, Angelo,Kohn, Luciana Konecny,Antonio, Marcia Aparecida,De Carvalho, Joao Ernesto,Pilli, Ronaldo Aloise
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p. 2927 - 2933
(2007/10/03)
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