- Domino Michael-aldol annulations for the stereocontrolled synthesis of bicyclo[3.3.1]nonane and bicyclo[3.2.1]octane derivatives
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Domino Michael-aldol annulation of cycloalkane-1,3-diones with enals affords a general route to 6-hydroxybicyclo[3.3.1]nonane-2,9-diones and 2-hydroxybicyclo[3.2.1]octane-6,8-diones, notably in one-pot procedures under convenient conditions. The annulation is shown to be compatible with one or more substituents at six positions of the bicyclo[3.3.1]nonane-2,9-dione scaffold. In some cases, the relative configuration of the product can be controlled by the appropriate choice of solvent, base and temperature for the annulation. In contrast to the chair-chair conformations usually adopted, the bicyclo compounds derived from 2,4,4-trimethylcyclohexane-1,3-dione possessed boat-chair conformations. Oxidation of the annulation products gave the corresponding bicyclo triketones.
- Promontorio, Rossella,Richard, Jean-Alexandre,Marson, Charles?M.
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p. 114412 - 114424
(2016)
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- Convenient preparation of synthetically useful chiral quaternary carbon-containing bicyclic compounds with organocatalysts
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Chiral quaternary carbon-containing bicyclic compounds possessing carbonyl functionalities were efficiently synthesized through asymmetric intramolecular aldol reactions with organocatalysts. Bicyclo [3.3.0] and [3.4.0] systems were constructed with a dia
- Kawamoto, Yuichiro,Noguchi, Naoki,Ozone, Daiki,Kobayashi, Toyoharu,Ito, Hisanaka
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supporting information
(2021/11/01)
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- Enantio- And Diastereoselective Construction of Contiguous Tetrasubstituted Chiral Carbons in Organocatalytic Oxadecalin Synthesis
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The organocatalytic enantio- and diastereoselective cycloetherification of 1,3-cyclohexanedione-bearing enones involving the in situ generation of chiral cyanohydrins was developed. This transformation offers the first catalytic asymmetric approach to oxa
- Wada, Yuuki,Murata, Ryuichi,Fujii, Yuki,Asano, Keisuke,Matsubara, Seijiro
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supporting information
p. 4710 - 4715
(2020/07/06)
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- Synthesis of (-)-mitrephorone A via a bioinspired late stage C-H oxidation of (-)-mitrephorone B
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We present a bioinspired late-stage C-H oxidation of the ent-trachylobane natural product mitrephorone B to mitrephorone A. The realization of this unprecedented transformation was accomplished by either an iron-catalyzed or electrochemical oxidation and enabled access to the densely substituted oxetane in one step. Formation of mitrephorone C, which is lacking the central oxetane unit but features a keto-function at C2, was not formed under these conditions.
- Wein, Lukas Anton,Wurst, Klaus,Angyal, Peter,Weisheit, Lara,Magauer, Thomas
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supporting information
p. 19589 - 19593
(2019/12/25)
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- Concise Enantioselective Synthesis of Oxygenated Steroids via Sequential Copper(II)-Catalyzed Michael Addition/Intramolecular Aldol Cyclization Reactions
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A new scalable enantioselective approach to functionalized oxygenated steroids is described. This strategy is based on chiral bis(oxazoline) copper(II) complex-catalyzed enantioselective and diastereoselective Michael reactions of cyclic ketoesters and enones to install vicinal quaternary and tertiary stereocenters. In addition, the utility of copper(II) salts as highly active catalysts for the Michael reactions of traditionally unreactive β,β′-enones and substituted β,β′-ketoesters that results in unprecedented Michael adducts containing vicinal all-carbon quaternary centers is also demonstrated. The Michael adducts subsequently undergo base-promoted diastereoselective aldol cascade reactions resulting in the natural or unnatural steroid skeletons. The experimental and computational studies suggest that the torsional strain effects arising from the presence of the Δ5-unsaturation are key controlling elements for the formation of the natural cardenolide scaffold. The described method enables expedient generation of polycyclic molecules including modified steroidal scaffolds as well as challenging-to-synthesize Hajos-Parrish and Wieland-Miescher ketones.
- Cichowicz, Nathan R.,Kaplan, Will,Khomutnyk, Yaroslav,Bhattarai, Bijay,Sun, Zhankui,Nagorny, Pavel
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supporting information
p. 14341 - 14348
(2015/11/27)
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- An easy route toward enantio-enriched polycyclic derivatives via an asymmetric domino conjugate reduction-aldol cyclization catalyzed by a chiral Cu(I) complex
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A highly efficient reductive-aldol cyclization mediated by a chiral Cu(I) complex and an organosilane yielded to cyclic or polycyclic derivatives. An excellent control of the selectivities was reached in most cases (dr up to 100:0 and ee up to 95%). After
- Deschamp, Julia,Hermant, Thomas,Riant, Olivier
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experimental part
p. 3457 - 3467
(2012/06/16)
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- Desymmetrizing reductive aldol cyclizations of enethioate derivatives of 1,3-diones catalyzed by a chiral copper hydride
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A range of enethioate derivatives of 1,3-diones underwent reductive aldol cyclizations catalyzed by a chiral copper hydride generated in situ from 5 mol% TaniaPhos (SL-T001-1), 5 mol% Cu(OAc)2·H2O, 5 mol% bipyridine and 2.0 equiv. of PhSiH3, to furnish polycyclic β-hydroxythioester products bearing three newly established contiguous stereocenters, with >98:2 dr and in up to 94% yield and 98% ee. The use of an amine such as bipyridine or 2,6-lutidine as additive results in an increase of the overall reaction rate. The major bicyclic aldol product has all substituents cis and can be rationalized by a reductively generated (Z)-enolate reacting with the dione via a cyclic transition state.
- Ou, Jun,Wong, Wing-Tak,Chiu, Pauline
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supporting information; experimental part
p. 5971 - 5978
(2012/08/28)
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- Toward an integrated route to the vernonia allenes and related sesquiterpenoids
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The synthesis of a model endocyclic allene related to the vernonia allenes is described. Fragmentation of a suitable decalin derivative gave the simplified germacrane scaffold. Computational analysis of this and related substrates provides insight into th
- Xu, Da,Drahl, Michael A.,Williams, Lawrence J.
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supporting information; experimental part
p. 937 - 943
(2011/09/16)
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- Synthesis of racemic and enantiomerically pure acetylenic -keto esters derived from 2-methyl-1,3-cycloalkanediones and 2-methylcycloalkanones respectively
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Racemic and enantiomerically pure alkynyl esters tethered, respectively, to 2-methyl-1,3-cycloalkanediones and 2-methylcycloalkanones were readily obtained starting from common intermediates, which were available on large scale.
- Geoffroy, Philippe,Ballet, Marie-Paule,Finck, Sidonie,Marchioni, Eric,Marcic, Christophe,Miesch, Michel
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scheme or table
p. 171 - 179
(2010/04/28)
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- Efficient construction of polycyclic derivatives via a highly selective cui-catalyzed domino reductive-aldol cyclization
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A versatile methodology for the diastereo-and enantioselective domino reductive-aldol cyclizations is reported. By using a copper (l)/diphosphane ligand, various five-and six-membered rings were generated with good to excellent diastereo-and enantioselect
- Deschamp, Julia,Riant, Olivier
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supporting information; experimental part
p. 1217 - 1220
(2009/10/02)
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- B-alkylcatecholborane-mediated tandem radical conjugated addition-aldol cyclization
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Image Presented A one-pot procedure involving radical conjugate addition of B-alkylcatecholboranes to enones followed by intramolecular aldol reaction is reported. Application to the stereoselective synthesis of monocyclic and bicyclic products with up to
- Beauseigneur, Alice,Ericsson, Cecilia,Renaud, Philippe,Schenk, Kurt
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supporting information; experimental part
p. 3778 - 3781
(2011/02/28)
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- An efficient route for the synthesis of methyl (-)-1,4a-dimethyl-5-oxodecahydronaphthalene-1-carboxylate by using baker's yeast-catalyzed asymmetric reduction
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Methyl (-)-1,4a-dimethyl-5-oxodecahydronaphthalene-1-carboxylate 1, a key synthetic intermediate for the synthesis of terpenoids, was efficiently synthesized by using a baker's yeast-catalyzed asymmetric reduction of a σ-symmetrical 1,3-cyclohexanedione d
- Katoh, Takahiro,Mizumoto, Shinsuke,Fudesaka, Masato,Takeo, Masatoshi,Kajimoto, Tetsuya,Node, Manabu
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p. 1655 - 1662
(2007/10/03)
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- Inversion of diastereoselectivity depending on substrate concentration in baker's yeast catalyzed reduction of σ-symmetrical 1,3-cyclopentadiones and 1,3-cyclohexadiones
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Inversion of diastereoselectivity caused by a change in substrate concentration was first observed in baker's yeast catalyzed reduction of σ-symmetrical 2,2-dialkylated cyclopentan-1,3-diones 1,2 and cyclohexan-1,3-dione 20. The selectivity altered by deg
- Katoh, Takahiro,Mizumoto, Shinsuke,Fudesaka, Masato,Nakashima, Yuki,Kajimoto, Tetsuya,Node, Manabu
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p. 2176 - 2182
(2007/10/03)
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- Enolate generation under hydrogenation conditions: catalytic aldol cycloreduction of keto-enones.
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[reaction: see text] Formal heterolytic activation of elemental hydrogen under Rh catalysis enables the reductive generation of enolates from enones under hydrogenation conditions. Enolates generated in this fashion participate in catalytic C-C bond formation via carbonyl addition to aldehyde and, as demonstrated in this account, ketone partners. Notably, the use of appendant dione partners enables diastereoselective formation of cycloaldol products possessing 3-stereogenic centers, including 2-contiguous quaternary centers.
- Huddleston, Ryan R,Krische, Michael J
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p. 1143 - 1146
(2007/10/03)
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