- Copper-Catalyzed Enantiotopic-Group-Selective Allylation of gem-Diborylalkanes
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We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination of copper(I) bromide and H8-BINOL derived phosphoramidite ligand proved to be the most effective catalytic system to provide various enantioenriched homoallylic boronate esters, containing a boron-substituted stereogenic center that is solely derived from gem-diborylalkanes, in good yields with high enantiomeric ratios under mild conditions. Experimental and theoretical studies have been conducted to elucidate the reaction mechanism, revealing how the enatiotopic-group-selective transmetalation of gem-diborylalkanes with chiral copper complex occurs to generate chiral α-borylalkyl-copper species for the first time. Additional synthetic applications to the synthesis of various chiral building blocks are also included.
- Kim, Minjae,Park, Bohyun,Shin, Minkyeong,Kim, Suyeon,Kim, Junghoon,Baik, Mu-Hyun,Cho, Seung Hwan
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supporting information
p. 1069 - 1077
(2021/01/25)
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- Enantioselective hydroesterificative cyclization of 1,6-enynes to chiral γ-lactams bearing a quaternary carbon stereocenter
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A palladium-catalyzed asymmetric hydroesterification-cyclization of 1,6-enynes with CO and alcohol was developed to efficiently prepare a variety of enantioenriched γ-lactams bearing a chiral quaternary carbon center and a carboxylic ester group. The approach featured good to high chemo-, region-, and enantioselectivities, high atom economy, and mild reaction conditions as well as broad substrate scope. The correlation between the multiple selectivities of such process and the N-substitutes of the amide linker in the 1,6-enyne substrate has been depicted by the crystallographic evidence and control experiments.
- Dong, Kaiwu,Li, Huimin,Ren, Xinyi,Shen, Chaoren,Tang, Lin,Wang, Peng
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p. 3561 - 3566
(2021/05/29)
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- Complex Polyheterocycles and the Stereochemical Reassignment of Pileamartine A via Aza-Heck Triggered Aryl C-H Functionalization Cascades
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Structurally complex benzo- and spiro-fused N-polyheterocycles can be accessed via intramolecular Pd(0)-catalyzed alkene 1,2-aminoarylation reactions. The method uses N-(pentafluorobenzoyloxy)carbamates as the initiating motif, and this allows aza-Heck-type alkene amino-palladation in advance of C-H palladation of the aromatic component. The chemistry is showcased in the first total synthesis of the complex alkaloid (+)-pileamartine A, which has resulted in the reassignment of its absolute stereochemistry.
- Bower, John F.,Caiger, Lewis,García-Cárceles, Javier,Hazelden, Ian R.,Jones, Benjamin T.,Langer, Thomas,Lewis, Richard J.
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supporting information
p. 15593 - 15598
(2021/10/12)
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- Asymmetric Reductive and Alkynylative Heck Bicyclization of Enynes to Access Conformationally Restricted Aza[3.1.0]bicycles
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Conformationally restricted azabicycles are becoming increasingly important in medicinal research. Asymmetric Heck bicyclization of enynes proceeds to give medicinally useful aza[3.1.0] and aza[4.1.0] bicycles with excellent enantioselectivity. The key organopalladium species after bicyclization can be trapped by silanes and terminal alkynes.
- Chi, Yonggui Robin,Huang, Xiaolei,Nguyen, Minh Hieu,Pu, Maoping,Wu, Yun-Dong,Zhang, Luoqiang,Zhou, Jianrong Steve
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supporting information
p. 10814 - 10818
(2020/06/09)
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- Copper-Catalyzed Enantioselective Hydroalkoxylation of Alkenols for the Synthesis of Cyclic Ethers
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The copper-catalyzed enantioselective intramolecular hydroalkoxylation of unactivated alkenes for the synthesis of tetrahydrofurans, phthalans, isochromans, and morpholines from 4- and 5-alkenols is reported. The substrate scope is complementary to existing enantioselective alkene hydroalkoxylations and is broad with respect to substrate backbone and alkene substitution. The asymmetric induction and isotopic labeling studies support a polar/radical mechanism involving enantioselective oxycupration followed by C-[Cu] homolysis and hydrogen atom transfer. Synthesis of the antifungal insecticide furametpyr was accomplished.
- Chen, Dake,Berhane, Ilyas A.,Chemler, Sherry R.
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supporting information
p. 7409 - 7414
(2020/06/29)
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- Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
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Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
- He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
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p. 2328 - 2332
(2020/01/08)
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- When Gold Meets Perfumes: Synthesis of Olfactive Compounds via Gold-Catalyzed Cycloisomerization Reactions
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An efficient, and mild synthetic route for the preparation of functionalized volatile oxa-bicyclo[4.1.0]-hept-4-ene (29 compounds, 44-98% isolated yields) has been developed relying on the association of IPrAuCl with NaBArF. The remarkable selectivity was demonstrated on a 1 g and 25 g scale with low catalyst loadings. The synthetic utility of these low-molecular-weight enols was further demonstrated by the derivatization of some adducts and by the unprecedented olfactory evaluation of all bicyclic derivatives.
- Laher, Romain,Marin, Christophe,Michelet, Véronique
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p. 4058 - 4062
(2020/04/20)
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- Intramolecular Remote C-H Activation via Sequential 1,4-Palladium Migration to Access Fused Polycycles
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An unprecedented intramolecular remote C-H activation via sequential 1,4-palladium migration with an aromatic ring as a conveyor has been described. This reaction provides an efficient route to construct diverse polycyclic frameworks in moderate to good yield via palladium-catalyzed remote C-H activation/alkene insertion, arylation, alkenylation, and the Heck reaction. The preliminary mechanistic studies revealed that the 1,4-palladium migration process was reversible.
- Li, Panpan,Li, Qiuyu,Weng, He,Diao, Jiaming,Yao, Hequan,Lin, Aijun
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supporting information
p. 6765 - 6769
(2019/09/07)
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- Traversing Steric Limitations by Cooperative Lewis Base/Palladium Catalysis: An Enantioselective Synthesis of α-Branched Esters Using 2-Substituted Allyl Electrophiles
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Cooperative catalysis enables the direct enantioselective α-allylation of linear prochiral esters with 2-substituted allyl electrophiles. Critical to the successful development of the method was the recognition that metal-centered reactivity and the sourc
- Schwarz, Kevin J.,Pearson, Colin M.,Cintron-Rosado, Gabriel A.,Liu, Peng,Snaddon, Thomas N.
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supporting information
p. 7800 - 7803
(2018/06/26)
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- Switchable Site-Selective Catalytic Carboxylation of Allylic Alcohols with CO2
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A switchable site-selective catalytic carboxylation of allylic alcohols has been developed in which CO2 is used with dual roles, both facilitating C?OH cleavage and as a C1 source. This protocol is characterized by its mild reaction conditions, absence of stoichiometric amounts of organometallic reagents, broad scope, and exquisite regiodivergency which can be modulated by the type of ligand employed.
- van Gemmeren, Manuel,B?rjesson, Marino,Tortajada, Andreu,Sun, Shang-Zheng,Okura, Keisho,Martin, Ruben
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p. 6558 - 6562
(2017/05/29)
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- Synthesis of Chiral Tertiary Boronic Esters by Oxime-Directed Catalytic Asymmetric Hydroboration
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Chiral boronic esters are useful intermediates in asymmetric synthesis. We have previously shown that carbonyl-directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters. We now report that the oxime-directed CAHB of alkyl-substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime-containing chiral tertiary boronic esters with yields up to 87 % and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O-substituted hydroxylamines, the generation of quaternary carbon stereocenters through carbon-carbon coupling reactions, and the preparation of chiral 3,4,4-trisubstituted isoxazolines.
- Shoba, Veronika M.,Thacker, Nathan C.,Bochat, Andrew J.,Takacs, James M.
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supporting information
p. 1465 - 1469
(2016/02/12)
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- An Umpolung Approach to Alkene Carboamination: Palladium Catalyzed 1,2-Amino-Acylation, -Carboxylation, -Arylation, -Vinylation, and -Alkynylation
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Conventional approaches to Pd-catalyzed alkene 1,2-carboamination rely upon the combination of a nucleophilic nitrogen-based component and an internal C-based or external oxidant. In this study, we outline an umpolung approach, which is triggered by oxidative initiation at an electrophilic N-based component and employs "standard" organometallic nucleophiles to introduce the new carbon-based fragment. Specifically, oxidative addition of a Pd(0)-catalyst into the N-O bond of O-pentafluorobenzoyl oxime esters generates imino-Pd(II) intermediates, which undergo 5-exo cyclization with sterically diverse alkenes. The resultant alkyl-Pd(II) intermediates are intercepted by organometallic nucleophiles or alcohols, under carbonylative or noncarbonylative conditions, to provide 1,2-carboamination products. This approach provides, for the first time, a unified strategy for achieving alkene 1,2-amino-acylation, -carboxylation, -arylation, -vinylation, and -alkynylation. For carbonylative processes, orchestrated protodecarboxylation of the pentafluorobenzoate leaving group underpins reaction efficiency. This process is likely a key feature in related Narasaka-Heck cyclizations and accounts for the efficacy of O-pentafluorobenzoyl oxime esters in aza-Heck reactions of this type. (Chemical Equation Presented).
- Faulkner, Adele,Scott, James S.,Bower, John F.
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p. 7224 - 7230
(2015/06/25)
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- Lewis Acid Catalyzed Formal Intramolecular [3 + 3] Cross-Cycloaddition of Cyclopropane 1,1-Diesters for Construction of Benzobicyclo[2.2.2]octane Skeletons
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A novel Lewis acid catalyzed formal intramolecular [3 + 3] cross-cycloaddition (IMCC) of cyclopropane 1,1-diesters has been successfully developed. This supplies an efficient and conceptually new strategy for construction of bridged bicyclo[2.2.2]octane skeletons. This [3 + 3]IMCC could be run up to gram scale and from easily prepared starting materials. This [3 + 3]IMCC, together with our previously reported [3 + 2]IMCC strategy, can afford either the bicyclo[2.2.2]octane or bicyclo[3.2.1]octane skeletons from the similar starting materials by regulating the substituents on vinyl group.
- Ma, Weiwei,Fang, Jie,Ren, Jun,Wang, Zhongwen
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p. 4180 - 4183
(2015/09/15)
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- NEW ARYLALKENYLPROPARGYLAMINE DERIVATIVES EXHIBITING NEUROPROTECTIVE ACTION FOR THE TREATMENT OF NEURODEGENERATIVE DISEASES
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The invention relates to novel arylalkenylpropargylamine derivatives of general formula (I) or enantiomers or diastereomers thereof or salts, optionally pharmaceutically acceptable salts, or solvates of any of these. The compounds can be used in treating or preventing a disease or condition in a mammal related to monoamine oxidase dysfunction, especially in neurodegenerative diseases, e.g. Parkinson's disease, Alzheimer's disease or Huntington's disease.
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Page/Page column 28; 29; 94
(2015/06/25)
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- Palladium-catalyzed oxidative heck-type allylation of β,β- disubstituted enones with allyl carbonates
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The palladium-catalyzed oxidative Heck-type allylation of β,β-disubstituted enones, i.e., α-oxoketene dithioacetals, was efficiently realized with allyl carbonates, providing a concise route to highly functionalized dienes. The present synthetic methodology utilizes the substrate activation strategy to activate the C-H bond of β,β-disubstituted enones by introduction of a 1,2-dithiolane functionality to make the enone substrate highly polarized and thus increase its reactivity, demonstrating rare examples for transition metal-catalyzed allylic substitution of ss,ss-disubstituted enones through a Heck-type allylation process.
- Jin, Weiwei,Yang, Qin,Wu, Ping,Chen, Jiping,Yu, Zhengkun
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supporting information
p. 2097 - 2102
(2014/07/07)
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- On the stereochemistry of the Baker's Yeast-mediated reduction of regioisomeric unsaturated aldehydes: Examples of enantioselectivity switch promoted by substrate-engineering
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The Baker's Yeast (BY) reduction of (Z)-2-chloromethyl-3-arylacrylaldehydes was found to afford (R)-2-methyl-3-aryl-propanols showing high enantiomeric excess values. Deuterium incorporation experiments were performed, in order to investigate the mechanism of the bioreduction: the formation of the corresponding substituted 2-benzylacrylaldehydes, as intermediates to be effectively reduced by Baker's Yeast, was suggested. These intermediates were synthesized and submitted to BY reduction to afford the corresponding saturated (R)-alcohols, thus confirming the conclusions drawn from labelling experiments. The enantioselectivity of their bioreduction was found to be opposite with respect to that observed for the corresponding regioisomeric 2-methylcinnamaldehydes. The preparation of the two enantiomers of 2-methyl-3-aryl-propanols by fermentation of two regioisomers represents an interesting example of substrate-controlled enantioselective reaction.
- Brenna, Elisabetta,Fronza, Giovanni,Fuganti, Claudio,Gatti, Francesco G.,Manfredi, Alessia,Parmeggiani, Fabio,Ronchi, Paolo
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- Palladium-catalyzed atom transfer radical cyclization of unactivated alkyl iodide
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A palladium-catalyzed atom transfer cyclization of unactivated alkyl iodide has been developed. A radical chain mechanism has been proposed for this transformation, which might not involve an alkylpalladium intermediate.
- Liu, Hui,Qiao, Zongjun,Jiang, Xuefeng
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supporting information; experimental part
p. 7274 - 7277
(2012/09/25)
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- Highly enantioselective Rh-catalyzed hydrogenation of β,γ- unsaturated phosphonates with chiral ferrocene-based monophosphoramidite ligands
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(Chemical Equation Presented) An enantioselective synthesis of chiral alkylphosphonates bearing a β-stereogenic center, based on the Rh-catalyzed asymmetric hydrogenation of corresponding β-substituted β,γ-unsaturated phosphonates with a ferrocene-based monophosphoramidite ligand under the mild hydrogenation conditions, was developed, in which an ee value of up to 98% was obtained.
- Duan, Zheng-Chao,Hu, Xiang-Ping,Zhang, Cheng,Wang, Dao-Yong,Yu, Sai-Bo,Zheng, Zhuo
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supporting information; experimental part
p. 9191 - 9194
(2010/03/04)
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- Sequential C-Si bond formations from diphenylsilane: Application to silanediol peptide isostere precursors
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The report of silanediol peptide isosteres as highly active inhibitors of proteolytic enzymes has triggered an increased interest for these compounds, thereby necessitating a general and direct synthetic access to this unusual class of protease inhibitors. In this paper, we report on thetwo-step assembly of the carbon-silicon backbone of a silane-containing dipeptide fragment. The synthetic scheme is comprised of an alkene hydr osilylation step with the simple precursor, diphenylsilane, using eithera radical initiator or RhCl(PPh 3)3, Wilkinson's catalyst, for the creation of a hydridosilane and the first new carbon-s ilicon bond. The next step is the reduction of this hydridosilane with lithium metal providing a silyl lithium reagent, which undergoes a highlydiastereoselective addition to an optically active tert-butanesulfinimi ne, thus generating the second C-Si bond. This method allows sequential functionalization of the two hydrides in diphenylsilane by chemoselective discrimination.
- Nielsen, Lone,Skrydstrup, Troels
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supporting information; experimental part
p. 13145 - 13151
(2009/03/12)
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- Palladium-catalyzed Heck arylations of allyl alcohols in ionic liquids: Remarkable base effect on the selectivity
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Pd-catalyzed Heck arylation of allyl alcohols in tetraalkylammonium ionic liquids (ILs) can be made highly selective toward the formation of either aromatic carbonyl compounds or aromatic conjugated alcohols by carefully choosing both the IL and the base.
- Calo, Vincenzo,Nacci, Angelo,Monopoli, Antonio,Ferola, Valentina
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p. 2596 - 2601
(2007/10/03)
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- Dipodal ligands from chiral spiro[2.4]hepta-4,6-dienes: Solid state conformational effects by tether substitution in dipodal η5,η1-CpP-ruthenium(II) complexes
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New chiral spiro[2.4]hepta-4,6-dienes were prepared and used in an efficient synthesis of cyclopentadienyl ruthenium complexes with pendant phosphine donors. Solid state structures reveal a conformation trend among three structurally homologous complexes
- Gorman, Jeffrey S.T.,Lynch, Vincent,Pagenkopf, Brian L.,Young, Brandon
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p. 5435 - 5439
(2007/10/03)
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- Stereoselective pinacol-type rearrangement of 2,3-epoxy alcohols with retention of configuration mediated by bis(iodozincio)methane
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Retention of the configuration is observed in the pinacol-type rearrangement of 2,3-epoxy alcohols 1 in the presence of bis(iodozincio)methane (2). The 1,3-migration of the hydroxymethyl group affords an intermediate 2-hydroxyaldehyde, which is methylenat
- Matsubara, Seijiro,Yamamoto, Hiromasa,Oshima, Koichiro
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p. 2837 - 2840
(2007/10/03)
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- Chemoenzymatic deracemization of (±)-2,2-disubstituted oxiranes
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The preparation of vicinal diols in up to 98% e.e. and 98% yield from the corresponding (±)-2,2-disubstituted epoxides was achieved via an enantioconvergent two-step hydrolysis: Thus, enantioselective enzymatic hydrolysis of the (S)-epoxide proceeded with retention of configuration furnishing the corresponding (S)-diol. In a subsequent step, the remaining (R)-oxirane was hydrolyzed during workup under acid catalysis with complete inversion of configuration yielding the (5)-diol. A detailed study of the latter reaction revealed that the experimental conditions have to be carefully chosen with respect to (i) nature of the acid, (ii) the solvent, and (iii) its water content to avoid racemization.
- Orru, Romano V. A.,Mayer, Sandra F.,Kroutil, Wolfgang,Faber, Kurt
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p. 859 - 874
(2007/10/03)
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- Reactions of 2-substituted epichlorohydrins
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2-Substituted epichlorohydrins have been synthesized by starting with 1,2-dichloro acetone and various alkyl and aryl halides via dichlorohydrins followed by cyclization. The reactive 2-substituted epichlorohydrins were subjected to nucleophilic attacking of azide and cyanide ions to afford corresponding β-azido alcohols and α,β-unsaturated nitriles.
- Tanyeli,Demir,Akhmedov,Ozgul,Kandemir
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p. 2967 - 2980
(2007/10/03)
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- PALLADIUM-CATALYZED REACTION OF 3-BROMOINDOLE DERIVATIVE WITH ALLYL ESTERS IN THE PRESENCE OF HEXA-n-BUTYLDISTANNANE
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The palladium-catalyzed cross-coupling reaction of ethyl 3-bromo-1-tosylindole-2-carboxylate (9) with a variety of substituted allylic acetates or carbonates (10) in the presence of hexa-n-butyldistannane (6) gave 3-allylated indoles (11) in high yields.
- Yokoyama, Yuusaku,Ikeda, Masato,Saito, Masaaki,Yoda, Tomoko,Suzuki, Hideharu,Murakami, Yasuoki
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p. 1505 - 1511
(2007/10/02)
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- NICKEL-CATALYZED REGIOSELECTIVE ALLYLATION OF ALLYLIC ALCOHOLS
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Regioselective allylmetallation of allylic alcohol has been accomplished by treatment with allylzinc in the presence of a nickel catalyst.Benzylic protective group of allyl alcohol facilitates the allylmetallation.
- Yanagisawa, Akira,Nomura, Nobuyoshi,Habaue, Shigeki,Yamamoto, Hisashi
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p. 6409 - 6412
(2007/10/02)
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