- Stereospecific Photochemical Cyclization of Azidoquinone with E,E- and Z,Z-Dienes. Application to the Synthesis of an Importent Precursor toward Mitomycins
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Photochemical reaction of 5-azido-2-methoxy-3-methyl-1,4-benzoquinone with cis,cis-2,4-hexadien-1,6-diol derivatives stereoselectively affords the corresponding 2,3-dihydroindolquinone, which possesses trans configuration at 2,3-position and vinylic double bond preserves the original stereochemistry of the diene.It is efficiently converted to a key precursor in mitomycin synthesis.
- Naruta, Yoshinori,Nagai, Naoshi,Yokota, Tadafumi,Maruyama, Kazuhiro
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Read Online
- Total synthesis of lissoclinolide by acid-induced lactonization of an (E)-α-bromo-γ,δ-epoxy acrylate derivative
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The stereoselective total synthesis of lissoclinolide, a naturally occurring antibiotic and cytotoxic butenolide, was achieved in 10 steps including a highly E-selective Still-Gennari-type olefination and an acid-induced lactonization of an (E)-α-bromo-γ,δ-epoxy acrylate derivative. The key regioselective 5-exo lactonization could be regulated by using AcOH under kinetically controlled conditions.
- Kobayashi, Kenichi,Kuwahara, Keisuke,Tanaka, Kosaku,Kunimura, Risako,Kogen, Hiroshi
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p. 1019 - 1027
(2019/04/26)
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- Low-pressure synthesis of cyclohexanedimethanol and derivatives
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The invention is directed to a process for preparing a 1,4-disubstituted cyclohexane compound of formula (I): where A is —OH, —OR, Br, or Cl; and R is a silyl group, a hydrocarbyl group, or an acyl group having 1 to 12 carbon atoms. The process includes the steps of reacting ethylene with a (2E,4E)-hexa-2,4-diene compound to produce a 3,6-disubstituted cyclohex-1-ene compound, and hydrogenating the 3,6-disubstituted cyclohex-1-ene compound to yield the 1,4-disubstituted cyclohexane compound of formula (I).
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Page/Page column 7
(2015/09/23)
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- Asymmetric hetero-Diels-Alder reaction of diazenes catalyzed by chiral silver phosphate: Water participates in the catalysis and stereocontrol
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The chiral silver phosphate was confirmed to efficiently catalyze a highly regio- and enantioselective hetero-Diels-Alder reaction of diazenes to furnish piperazine derivatives in high yields and excellent ee values. DFT calculations revealed that the wat
- Liu, Bin,Liu, Tong-Yu,Luo, Shi-Wei,Gong, Liu-Zhu
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supporting information
p. 6164 - 6167
(2015/02/05)
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- A novel catalytic asymmetric route towards skipped dienes with a methyl-substituted central stereogenic carbon
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A highly efficient method for the enantioselective synthesis of 1,4-dienes (skipped dienes) with a methyl-substituted central stereogenic carbon using copper-catalysed asymmetric allylic alkylation of diene bromides was developed. Excellent regio- and enantioselectivity (up to 97 : 3 SN2′/ SN2 ratio and 99% ee) were achieved with broad substrate scope. The Royal Society of Chemistry 2013.
- Huang, Yange,Fananas-Mastral, Martin,Minnaard, Adriaan J.,Feringa, Ben L.
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supporting information
p. 3309 - 3311
(2013/06/04)
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- Total synthesis of (+)-roxaticin via C-C bond forming transfer hydrogenation: A departure from stoichiometric chiral reagents, auxiliaries, and premetalated nucleophiles in polyketide construction
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A total synthesis of the oxo-polyene macrolide (+)-roxaticin is achieved in 20 steps from 1,3-propanediol. In this approach, 9 of 10 C-C bonds formed in the longest linear sequence are made via metal catalysis, including 7 C-C bonds formed by iridium cata
- Han, Soo Bong,Hassan, Abbas,Kim, In Su,Krische, Michael J.
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supporting information; experimental part
p. 15559 - 15561
(2011/01/03)
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- Amplification of asymmetric induction in sequential reactions of bis-diazoacetates catalyzed by chiral dirhodium(II) carboxamidates
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(Chemical Equation Presented) Two sequential intramolecular carbon-hydrogen insertion or cyclopropanation reactions of bis-diazoacetates using chiral dirhodium(II) carboxamidate catalysts are reported. The initial metal carbene transformation forms an excess of one enantiomer that with the second transformation further enhances stereocontrol (kinetic amplification). Diastereoselectivity and enantioselectivity for product formation are controlled by the catalyst.
- Doyle, Michael P.,Wang, Yuanhua,Ghorbani, Pejman,Bappert, Erhard
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p. 5035 - 5038
(2007/10/03)
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- A Formal Total Synthesis of (+)-Tetronolide, the Aglycon of the Tetrocarcins: Enantio- and Diastereoselective Syntheses of the Octahydronaphthalene (Bottom-Half) and Spirotetronate (Top-Half) Fragments
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A formal total synthesis of (+)-tetronolide, the aglycon of the tetrocarcins, has been achieved by virtue of the development of highly diastereo- and enantioselective syntheses of the bottom- and top-half fragments 4 and 5 reported herein. These fragments previously served as key intermediates in Yoshii's pioneering total synthesis of (+)-tetronolide. The synthesis of the bottom-half octahydronaphthalene unit 4 features the intramolecular Diels-Alder reaction of tetraenal 20 and proceeds in 17 steps and 5-6% yield from D-glyceraldehyde pentylidene acetal 8. The synthesis of the spirotetronate fragment 5 features the highly enantioselective exo selective Diels-Alder reaction of triene 37 and chiral dienophile 25b and proceeds in 14 steps and 10% overall yield from cis-2-butene-1,4-diol (38). An enantioselective synthesis of Boeckman's top-half cyclohexene fragment 6 via the exo selective Diels-Alder reaction of diene 24 and dienophile 25a was also developed, but this route was deemed too inefficient for use in a projected total synthesis of the natural product. The syntheses of 5 and 6 provide important information on the utility of chiral dienophiles 25a and 25b in organic synthesis.
- Roush, William R.,Reilly, Melissa L.,Koyama, Kazuo,Brown, Bradley B.
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p. 8708 - 8721
(2007/10/03)
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- Asymmetric synthesis of bicyclopropane derivatives
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Both syn- and anti-bicyclopropane derivatives have been efficiently prepared with good relative and absolute stereocontrol using reagent controlled asymmetric cyclopropanation reactions. Double Simmons-Smith cyclopropanation of 2,4-dien-1-ols stereoselectively gave the corresponding anti-bicyclopropane derivatives.
- Barrett, Anthony G. M.,Doubleday, Wendel W.,Tustin, Gary J.
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p. 15325 - 15338
(2007/10/03)
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- Regio- and Enantioselective Catalytic Epoxidation of Conjugated Polyenes. Formal Synthesis of LTA4 Methyl Ester
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The (salen)Mn(III)-catalyzed asymmetric epoxidation reaction exhibits regioselectivity for attack at cis double bonds of conjugated dienes to afford enantiomerically enriched trans-vinyl epoxides as the major products.
- Chang, Sukbok,Lee, Nam Ho,Jacobsen, Eric N.
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p. 6939 - 6941
(2007/10/02)
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