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2 Cyclohexenone

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Fumie Sato – One of the best experts on this subject based on the ideXlab platform.

  • optically active trans 4 tert butyldimethylsiloxymethyl 5 tert butyldimethylsiloxy 2 Cyclohexenone as a useful chiral building block for preparation of substituted cyclohexane rings synthesis and its highly stereoselective reaction with rcu cn li
    Tetrahedron Letters, 2000
    Co-Authors: Takeshi Hanazawa, Masakazu Koiwa, Georges P.‐j. Hareau, Fumie Sato

    Abstract:

    Optically active trans-4-(tert-butyldimethylsiloxymethyl)-5-(tert-butyldimethylsiloxy)-2Cyclohexenone (2) has been synthesized in 25% overall yield starting from easily available 1,4-bis(benzyloxy)-2,3-epoxy butane (3). The enone 2 reacts with excellent stereoselectivity with RCu(CN)Li thus working as an efficient chiral building block for preparation of substituted cyclohexane compounds.

  • asymmetric synthesis of 1α 25 dihydroxyvitamin d3 a ring precursor starting with 5 tert butyldimethylsiloxy 2 Cyclohexenone
    Tetrahedron Letters, 2000
    Co-Authors: Georges P.‐j. Hareau, Masakazu Koiwa, Fumie Sato

    Abstract:

    Abstract The A-ring precursor of 1α,25-dihydroxyvitamin D3 [(E)-4] has been prepared starting from the (5S)-tert-butyldimethylsiloxy-2Cyclohexenone [(S)-1] via eight steps in 19% overall yield, where a catalytic osmium dihydroxylation which sets the stereochemistry of the hydroxyl group at C1 and a regioselective protection of the hydroxy group as a TBS-ether are the key steps.

  • Asymmetric synthesis of palitantin from the (5R)-tert-butyldimethylsiloxy-2Cyclohexenone
    Tetrahedron Letters, 1999
    Co-Authors: Georges P.‐j. Hareau, Masakazu Koiwa, Takeshi Hanazawa, Fumie Sato

    Abstract:

    Abstract (+)-Palitantin (2) has been synthesized in 25% overall yield from the (5R)-tert-butyldimethylsiloxy-2Cyclohexenone [(R)-1] where a remarkable diastereoselective cat. OsO4 cis-dihydroxylation of (R)-1 furnished the precursor of the optically pure (5R,6R)-bis-trimethylsiloxy 2Cyclohexenone (7) which underwent highly selectively the 1,4-addition reaction of the 1,3-heptadienyl cyanocuprate to give, after trapping of the corresponding copper enolate with formaldehyde, the target compound.

Georges P.‐j. Hareau – One of the best experts on this subject based on the ideXlab platform.

  • optically active trans 4 tert butyldimethylsiloxymethyl 5 tert butyldimethylsiloxy 2 Cyclohexenone as a useful chiral building block for preparation of substituted cyclohexane rings synthesis and its highly stereoselective reaction with rcu cn li
    Tetrahedron Letters, 2000
    Co-Authors: Takeshi Hanazawa, Masakazu Koiwa, Georges P.‐j. Hareau, Fumie Sato

    Abstract:

    Optically active trans-4-(tert-butyldimethylsiloxymethyl)-5-(tert-butyldimethylsiloxy)-2Cyclohexenone (2) has been synthesized in 25% overall yield starting from easily available 1,4-bis(benzyloxy)-2,3-epoxy butane (3). The enone 2 reacts with excellent stereoselectivity with RCu(CN)Li thus working as an efficient chiral building block for preparation of substituted cyclohexane compounds.

  • asymmetric synthesis of 1α 25 dihydroxyvitamin d3 a ring precursor starting with 5 tert butyldimethylsiloxy 2 Cyclohexenone
    Tetrahedron Letters, 2000
    Co-Authors: Georges P.‐j. Hareau, Masakazu Koiwa, Fumie Sato

    Abstract:

    Abstract The A-ring precursor of 1α,25-dihydroxyvitamin D3 [(E)-4] has been prepared starting from the (5S)-tert-butyldimethylsiloxy-2Cyclohexenone [(S)-1] via eight steps in 19% overall yield, where a catalytic osmium dihydroxylation which sets the stereochemistry of the hydroxyl group at C1 and a regioselective protection of the hydroxy group as a TBS-ether are the key steps.

  • Asymmetric synthesis of palitantin from the (5R)-tert-butyldimethylsiloxy-2Cyclohexenone
    Tetrahedron Letters, 1999
    Co-Authors: Georges P.‐j. Hareau, Masakazu Koiwa, Takeshi Hanazawa, Fumie Sato

    Abstract:

    Abstract (+)-Palitantin (2) has been synthesized in 25% overall yield from the (5R)-tert-butyldimethylsiloxy-2Cyclohexenone [(R)-1] where a remarkable diastereoselective cat. OsO4 cis-dihydroxylation of (R)-1 furnished the precursor of the optically pure (5R,6R)-bis-trimethylsiloxy 2Cyclohexenone (7) which underwent highly selectively the 1,4-addition reaction of the 1,3-heptadienyl cyanocuprate to give, after trapping of the corresponding copper enolate with formaldehyde, the target compound.

Carmen Claver – One of the best experts on this subject based on the ideXlab platform.

  • thioether phosphinite and diphosphinite ligands derived from d xylose for the copper catalyzed asymmetric 1 4 addition to 2 Cyclohexenone
    Tetrahedron-asymmetry, 2005
    Co-Authors: Eugeni Guimet, Montserrat Dieguez, Aurora Ruiz, Carmen Claver

    Abstract:

    Abstract A series of thioether–phosphinite 1–3 and diphosphinite 4 and 5 ligands, derived from inexpensive d -(+)-xylose, were tested for the first time in the Cu-catalyzed asymmetric 1,4-addition to 2Cyclohexenone 6. Good enantioselectivities (up to 72%) and activities [TOF up to >1225 mol (mol h−1)] combined with excellent selectivity in the 1,4 product were obtained. Our results show that activity and selectivity (chemo- and enantioselectivity) depend strongly on the type of functional group at the C-5 position of the carbohydrate backbone, the steric properties of the substituent in the thioether moiety, the catalyst precursor and the alkylating agent.

  • Thioether–phosphinite and diphosphinite ligands derived from d-xylose for the copper-catalyzed asymmetric 1,4-addition to 2Cyclohexenone
    Tetrahedron: Asymmetry, 2005
    Co-Authors: Eugeni Guimet, Montserrat Dieguez, Aurora Ruiz, Carmen Claver

    Abstract:

    Abstract A series of thioether–phosphinite 1–3 and diphosphinite 4 and 5 ligands, derived from inexpensive d -(+)-xylose, were tested for the first time in the Cu-catalyzed asymmetric 1,4-addition to 2Cyclohexenone 6. Good enantioselectivities (up to 72%) and activities [TOF up to >1225 mol (mol h−1)] combined with excellent selectivity in the 1,4 product were obtained. Our results show that activity and selectivity (chemo- and enantioselectivity) depend strongly on the type of functional group at the C-5 position of the carbohydrate backbone, the steric properties of the substituent in the thioether moiety, the catalyst precursor and the alkylating agent.

  • copper catalysed asymmetric 1 4 addition of organometallic reagents to 2 Cyclohexenone using novel phosphine phosphite ligands
    Tetrahedron-asymmetry, 2000
    Co-Authors: Montserrat Dieguez, Sirik Deerenberg, Oscar Pamies, Carmen Claver, P W N M Van Leeuwen, Paul C J Kamer

    Abstract:

    Abstract A series of novel non-symmetrical phosphine-phosphite ligands 1 – 10 have been tested in the copper-catalysed asymmetric addition of diethylzinc and triethylaluminium to 2Cyclohexenone. In all cases, excellent conversion and regioselectivities for the 1,4-product were found. Good enantiomeric excesses (up to 62%) were obtained when triethylaluminium was used as the alkylating reagent.