- Recoverable polystyrene-supported palladium catalyst for construction of all-carbon quaternary stereocenters via asymmetric 1,4-addition of arylboronic acids to cyclic enones
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The development of recoverable catalysts based on the combination of synthetically demanding ligands with transition metals attracts a lot of attention, especially from the environmental point of view. In this paper, we describe the preparation of a recoverable polystyrene supported chiral palladium catalyst based on PyOx ligand suitable for asymmetric 1,4-addition of arylboronic acids to cyclic 3-substituted five- and six-membered enones. In the reaction, all?carbon quaternary stereocenters are formed with a high level of enantioselectivity (up to 91% ee) and conversion (up to 99%). The catalyst was used in 6 cycles with no loss of enantioselectivity and only a small decrease in conversion. A solution of the problems associated with the transition from homogeneous to heterogeneous catalytic systems is discussed.
- Bartá?ek, Jan,Váňa, Ji?í,Drabina, Pavel,Svoboda, Jan,Kocúrik, Martin,Sedlák, Milo?
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- Catalytic asymmetric total syntheses of (+)-α-cuparenone, (+)-cuparene and (+)-herbertene
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A general catalytic asymmetric route to either enantiomers of sesquiterpenes, cuparenes (1–2) and herbertenes (8–9) is disclosed from commercially available 3-methyl cyclopenten-2-one. Following a catalytic enantioselective addition of arylboronic acids to enone 15, compounds 14a-b with all carbon quaternary stereocenters are synthesized in up to 90percent ee in the presence of Pd(II)-PyOx (pyridine oxazoline). Compounds 14a-b are used as precursors for the asymmetric total syntheses of (+)-cuparene (1a) (35percent overall yield in 3 steps), α-(+)-cuparenone (1b) (56percent overall yield in 2 steps), and (+)-herbertene (8a) (34percent overall yield in 3 steps).
- Shaw, Kundan,Niyogi, Sovan,Nandi, Rhituparna,Bisai, Vishnumaya
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supporting information
(2020/07/15)
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- Stepwise approach for sterically hindered Csp3-Csp3 bond formation by dehydrogenative: O -alkylation and Lewis acid-catalyzed [1,3]-rearrangement towards the arylalkylcyclopentane skeleton of sesquiterpenes
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A stepwise dehydrogenative cross-coupling method was developed for the formation of sterically hindered Csp3-Csp3 bonds. Intramolecular dehydrogenative O-alkylation of a β-ketoester by 2,3-dichloro-5,6-dicyano-p-benzoquinone to form an oxolane followed by Lewis acid-catalyzed [1,3]-rearrangement furnished the sesquiterpene arylmethylcyclopentane skeleton. The formal syntheses of herbertane-type β-herbertenol, cuparane-type enokipodins A and B were also achieved.
- Fujitani, Ban,Hanaya, Kengo,Sugai, Takeshi,Higashibayashi, Shuhei
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supporting information
p. 3621 - 3624
(2020/04/07)
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- Pyridine-Hydrazone Ligands in Asymmetric Palladium-Catalyzed 1,4- and 1,6-Additions of Arylboronic Acids to Cyclic (Di)enones
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Catalysts generated by combinations of Pd(TFA)2 and enantiomerically pure pyridine-hydrazone ligands have been applied to the 1,4-addition of arylboronic acids to β-substituted cyclic enones, building all-carbon quaternary stereocenters in high
- de Gracia Retamosa, María,álvarez-Casao, Yolanda,Matador, Esteban,Gómez, ángela,Monge, David,Fernández, Rosario,Lassaletta, José M.
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p. 176 - 184
(2018/12/11)
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- Efficient formation of benzylic quaternary centers via palladium catalysis
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Four's a crowd: An efficient protocol for the formation of benzylic quaternary centers via arylation of enones using a catalyst made from Pd(O 2CCF3)2 and 2,2′-bipyridine is developed. For cyclic substrates, catalyst loadi
- Gottumukkala, Aditya L.,Suljagic, Jasmin,Matcha, Kiran,De Vries, Johannes G.,Minnaard, Adriaan J.
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p. 1636 - 1639
(2013/10/21)
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- Palladium-catalyzed asymmetric quaternary stereocenter formation
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An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF 6, and provides products in up to 99 % enantiomeric excess, with good yields. Based on this strategy, (-)-α-cuparenone has been prepared in only two steps. Copyright
- Gottumukkala, Aditya L.,Matcha, Kiran,Lutz, Martin,De Vries, Johannes G.,Minnaard, Adriaan J.
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experimental part
p. 6907 - 6914
(2012/07/01)
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- A chiral pool based approach to antipodes of α-cuparenone
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A synthetic route to both antipodes of α-cuparenone was achieved from the readily available chiral pool starting material l-malic acid and involved cyclopentannulation as the key step.
- Chavan, Subhash P.,Lasonkar, Pradeep B.
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p. 1496 - 1500,5
(2012/12/12)
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- A chiral pool based approach to antipodes of α-cuparenone
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A synthetic route to both antipodes of α-cuparenone was achieved from the readily available chiral pool starting material l-malic acid and involved cyclopentannulation as the key step.
- Chavan, Subhash P.,Lasonkar, Pradeep B.
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p. 1496 - 1500
(2013/01/15)
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- Cyclopropyl methyl bromide-mediated gem-diallylation: Total synthesis of (±)-α-cuparenone
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The total synthesis of (±)-α-cuparenone, an aromatic sesquiterpene, has been described using the radical mediated gem-diallylation of substituted cyclopropyl methylbromide followed by ring-closing metathesis approach.
- Shivakumar,Salunke, Ganesh B.,Kumar, Suneel
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experimental part
p. 1952 - 1957
(2011/06/26)
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- An efficient and practical total synthesis of (±)-α-cuparenone
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A one-pot cyclopentannulation approach as the key step for the total synthesis of (±)-α-cuparenone is described. Georg Thieme Verlag Stuttgart.
- Chavan, Subhash P.,Dhawane, Abasaheb N.,Kalkote, Uttam R.
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p. 3827 - 3830
(2008/09/17)
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- Palladium-catalyzed intramolecular 5-endo-trig oxidative Heck cyclization: a facile pathway for the synthesis of some sesquiterpene precursors
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An efficient and convenient method for the construction of substituted cyclopentenones via palladium-catalyzed intramolecular 5-endo-trig oxidative cyclization has been introduced as a powerful new strategy for the synthesis of sesquiterpenes.
- Ray, Devalina,Paul, Sunanda,Brahma, Sulagna,Ray, Jayanta. K.
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p. 8005 - 8008
(2008/03/18)
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- A synthesis of α-cuparenone based on symmetry considerations
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A ring expansion approach to α-cuparenone was accomplished in 5 or 6 steps. The key intermediate is 3-methyl-3-(4-methylphenyl)cyclobutanone, which was derived from a [2-t-2]cycloaddition of dichloroketene on a styrene derivative, followed by dechlorinati
- Ho, Tse-Lok,Chang, May-Hua
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p. 621 - 624
(2007/10/03)
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- ENANTIOCONVERGENT SYNTHESIS OF (-)-α-CUPARENONE INVOLVING CHIRAL INVERSION OF A KETONE INTERMEDIATE
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The acid (-)-2 was converted to the ketone (-)-6.Unsaturated ketone (+)-14 was synthesised from (-)-6.The ketone (+)-7 prepared from the acid (+)-3 on 1,2-ketone transposition, furnished the optical antipode (-)-6.
- Gharpure, Milind M.,Rao, A.S.
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p. 1813 - 1824
(2007/10/02)
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- ENANTIOCONTROLLED SYNTHESIS OF QUATERNARY CARBON CENTERS. 3,3-DISUBSTITUTED CYCLOPENTANONES. (+)-α-CUPARENONE.
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Asymmetric synthetic methodology is introduced for preparation of 3,3-disubstituted cyclopentanones, including (+)-α-cuparenone, of high enantiomeric purity.
- Posner, Gary H.,Kogan, Timothy P.,Hulce, Martin
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p. 383 - 386
(2007/10/02)
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