- Short synthesis of epi-cytoxazone via oxazoline formation through intramolecular benzylic substitution of a bis-trichloroacetimidate
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A short and efficient method for synthesizing epi-cytoxazone via the corresponding oxazoline intermediate was developed. The formation of the oxazoline ring, which proceeds through an SN1 mechanism to ensure that the trans-oxazoline stereochemistry is retained, was induced by intramolecular benzylic substitution of a 1,2-bis-trichloroacetimidate, starting from the known enantiomerically pure diol.
- Matsushima, Yoshitaka,Ishikawa, Moe,Shibasaki, Rina,Nojima, Yuki
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p. 231 - 233
(2018/01/03)
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- DDQ mediated stereoselective intermolecular benzylic C[sbnd]N bond formation: Synthesis of (?)-cytoxazone, (?)-4-epi-cytoxazone and their analogues and immunological evaluation of their cytokine modulating activity
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A short and efficient strategy for the synthesis of (?)-cytoxazone, (?)-4-epi-cyoxazone and their analogues by using DDQ mediated diastereoselective intermolecular benzylic amination has been described. Immunological evaluation of their cytokine modulating activity revealed that the change of hydroxy methyl to methyl group increased the cellular immunity in in-vitro cultures. Changes in the stereochemistry of oxazolidine haven't influenced the biological activity.
- Lingamurthy, Macha,Nalliboina, Gopalal Rao,Rao, Maddimsetti Venkateswara,Rao, Batchu Venkateswara,Reddy, Bonam Srinivasa,Sampath Kumar, Halmuthur Mahabalarao
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p. 1473 - 1481
(2017/02/18)
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- Stereoselective synthesis of 4-substituted-cyclic sulfamidate-5-carboxylates by asymmetric transfer hydrogenation accompanied by dynamic kinetic resolution and applications to concise stereoselective syntheses of (-)-epi-cytoxazone and the taxotere side-c
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Dynamic kinetic resolution driven, asymmetric transfer hydrogenation reactions of cyclic sulfamidate imine-5-carboxylate esters were developed. Applications of the new methodology to stereoselective syntheses of the taxotere side-chain and (-)-epi-cytoxaz
- Kim, Jin-Ah,Seo, Yeon Ji,Kang, Soyeong,Han, Juae,Lee, Hyeon-Kyu
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p. 13706 - 13709
(2015/01/09)
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- An efficient, practical, and enantioselective method for synthesis of homoallenylamides catalyzed by an aminoalcohol-derived, boron-based catalyst
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A practical catalytic method for enantioselective addition of an allene unit to aldimines is disclosed. Transformations are promoted by an in-situ-generated B-based catalyst that is derived from a simple, robust, and readily accessible (in multigram quantities) chiral aminoalcohol. A range of aryl-, heteroaryl-, and alkyl-substituted homoallenylamides can be obtained in 66-91% yield and 84:16 to >99:1 enantiomeric ratio through reactions performed at ambient temperature and in the presence of 0.1-3.0 mol% of the chiral catalyst and a commercially available allenylboron reagent. The catalytic protocol does not require strict anhydrous conditions, can be performed on gram scale, and promotes highly selective addition of an allenyl unit (vs a propargyl group). The utility of the approach is demonstrated through development of succinct approaches to syntheses of anisomycin and epi-cytoxazone.
- Wu, Hao,Haeffner, Fredrik,Hoveyda, Amir H.
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p. 3780 - 3783
(2014/04/03)
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- Synthesis of 2-oxazolidinones from β-lactams: Stereospecific total synthesis of (-)-cytoxazone and all of its stereoisomers
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The synthetic correlation between two different antibiotic frameworks, the β-lactams and 2-oxazolidinones, is described for the first time. In this approach, 2-oxazolidinones are prepared in stereomerically pure form from 3-hydroxy β-lactams by a ring-ope
- Mishra, Rajesh Kumar,Coates, Cristina M.,Revell, Kevin D.,Turos, Edward
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p. 575 - 578
(2008/02/02)
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- Diastereoselective and enantioselective Henry (nitroaldol) reaction utilizing a guanidine-thiourea bifunctional organocatalyst
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A highly enantio- and diastereoselective Henry reaction of various aldehydes with nitroethane was developed using the guanidine-thiourea bifunctional catalyst 1 (syn selectivity of 86:14 to 99:1 with 84-99% ee). A variety of nitroalkanes was treated with
- Sohtome, Yoshihiro,Hashimoto, Yuichi,Nagasawa, Kazuo
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p. 2894 - 2897
(2007/10/03)
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- A concise synthesis of (-)-cytoxazone and (-)-4-epi-cytoxazone using chlorosulfonyl isocyanate
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A concise synthesis of (-)-cytoxazone and its stereoisomer (-)-4-epi-cytoxazone, novel cytokine modulators, has been accomplished each in six steps from readily available p-anisaldehyde with good diastereoselectivity. Key steps in the synthesis include th
- Kim, In Su,Kim, Ji Duck,Ryu, Chae Baek,Zee, Ok Pyo,Jung, Young Hoon
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p. 9349 - 9358
(2007/10/03)
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- Enantioselective synthesis of (-)-cytoxazone and (+)-epi-cytoxazone, novel cytokine modulators via Sharpless asymmetric epoxidation and l-proline catalyzed Mannich reaction
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A short and efficient enantioselective synthesis of (-)-cytoxazone and its stereoisomer (+)-epi-cytoxazone, novel cytokine modulators, has been described with good yield and enantioselectivity. Ti-catalyzed Sharpless asymmetric epoxidation of allyl alcoho
- Paraskar, Abhimanyu S.,Sudalai, Arumugam
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p. 5756 - 5762
(2007/10/03)
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- Direct catalytic asymmetric Mannich-type reaction of hydroxyketone using a Et2Zn/linked-BINOL complex: Synthesis of either anti- or syn-β-amino alcohols
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Full details of a direct catalytic asymmetric Mannich-type reaction of a hydroxyketone using a Et2Zn/(S,S)-linked-BINOL complex are described. By choosing the proper protective groups on imine nitrogen, either anti- or syn-β-amino alcohol was obtained in good diastereomeric ratio, yield, and excellent enantiomeric excess using the same zinc catalysis. N-Diphenylphosphinoyl (Dpp) imine 3 gave anti-β-amino alcohols in anti/syn = up to >98/2, up to >99% yield, and up to >99.5% ee, while Boc-imine 4 gave syn-β-amino alcohols in anti/syn = up to 5/95, up to >99% yield, and up to >99.5% ee. The high catalyst turnover number (TON) is also noteworthy. Catalyst loading was successfully reduced to 0.02 mol % (TON = up to 4920) for the anti-selective reaction and 0.05 mol % (TON = up to 1760) for the syn-selective reaction. The Et2Zn/(S,S)-linked-BINOL complex exhibited far better TON than in previous reports of catalytic asymmetric Mannich-type reactions. Mechanistic studies to clarify the reason for the high catalyst efficiency as well as transformations of Mannich adducts are also described.
- Matsunaga, Shigeki,Yoshida, Takamasa,Morimoto, Hiroyuki,Kumagai, Naoya,Shibasaki, Masakatsu
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p. 8777 - 8785
(2007/10/03)
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- Imino 1,2-Wittig rearrangement of hydroximates and its application to synthesis of cytoxazone
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The imino 1,2-Wittig rearrangement of hydroximates provides a novel method for the construction of 2-hydroxyoxime ethers. Upon treatment with LDA, Z-hydroximates smoothly underwent stereoselective rearrangement to give Z-2-hydroxyoxime ethers in good yield, which were converted into amino alcohols. On the other hand, the rearrangement of E-hydroximates gave a mixture of E- and Z-2-hydroxyoxime ethers. This method was successfully applied to a practical synthesis of cytoxazone.
- Miyata, Okiko,Koizumi, Tomoko,Asai, Hiroshi,Iba, Ryuichi,Naito, Takeaki
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p. 3893 - 3914
(2007/10/03)
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- A new synthesis of cytoxazone and its diastereomers provides key initial SAR information
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A short, enantioselective, and diastereoselective synthesis of cytoxazone, a Th2-selective immunomodulator from Streptomyces, is described. The route was readily adapted to the synthesis of the three other stereoisomers of natural cytoxazone. Evaluation of these compounds revealed that the stereochemical configuration of the oxazolidinone ring did not influence their biological activity.
- Carter, Percy H.,LaPorte, Jacob R.,Scherle, Peggy A.,Decicco, Carl P.
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p. 1237 - 1239
(2007/10/03)
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- Chemoenzymatic synthesis of all four cytoxazone stereoisomers
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Racemic cytoxazone (±-5) was synthesized starting from easily available glycidic ester (±)-1 by nucleophilic epoxide ring opening, followed by 2-oxazolidinone ring construction and calcium chloride/sodium borohydride reduction of the intermediary ester (±
- Hamersak,Ljubovic,Mercep,Mesic,Sunjic
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p. 1989 - 1992
(2007/10/03)
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- Synthetic applications of the cyclic iminocarbonate rearrangement Enantioselective syntheses of chloramphenicol and 4-epi-cytoxazone
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Chloramphenicol and 4-epi-cytoxazone have been enantioselectively synthesized using the asymmetric dihydroxylation and the cyclic iminocarbonate rearrangement as key steps. (C) 2000 Elsevier Science Ltd.
- Park, Jung Nam,Ko, Soo Y.,Koh, Hun Y.
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p. 5553 - 5556
(2007/10/03)
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- Stereoselective syntheses of cytoxazone, a novel cytokine modulator, and its stereoisomers
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Cytoxazone, a novel cytokine modulator, and its stereoisomers were stereoselectively synthesized via stereocontrolled introduction of an azide group and direct construction of the 2-oxazolidinone ring from an azide carbonate by reductive cyclization.
- Sakamoto, Yasuharu,Shiraishi, Akiko,Seonhee, Jeong,Nakata, Tadashi
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p. 4203 - 4206
(2007/10/03)
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