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Odagi M, Furukori K, Takayama K, Noguchi K, Nagasawa K. Total Synthesis of Rishirilide B by Organocatalytic Oxidative Kinetic Resolution: Revision of Absolute Configuration of (+)-Rishirilide B. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701431] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Minami Odagi
- Department of Biotechnology and Life Science; Tokyo University of Agriculture and Technology; 2-24-16, Naka-cho, Koganei Tokyo 184-8588 Japan
| | - Kota Furukori
- Department of Biotechnology and Life Science; Tokyo University of Agriculture and Technology; 2-24-16, Naka-cho, Koganei Tokyo 184-8588 Japan
| | - Kan Takayama
- Department of Biotechnology and Life Science; Tokyo University of Agriculture and Technology; 2-24-16, Naka-cho, Koganei Tokyo 184-8588 Japan
| | - Keiichi Noguchi
- Instrumentation Analysis Center; Tokyo University of Agriculture and Technology, Koganei; Tokyo 184-8588 Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science; Tokyo University of Agriculture and Technology; 2-24-16, Naka-cho, Koganei Tokyo 184-8588 Japan
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Odagi M, Furukori K, Takayama K, Noguchi K, Nagasawa K. Total Synthesis of Rishirilide B by Organocatalytic Oxidative Kinetic Resolution: Revision of Absolute Configuration of (+)-Rishirilide B. Angew Chem Int Ed Engl 2017; 56:6609-6612. [PMID: 28471011 DOI: 10.1002/anie.201701431] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Indexed: 01/23/2023]
Abstract
Described herein is the enantioselective syntheses of (+)- and (-)-rishirilide B from the corresponding optically active β-substituted tetralones, which were obtained by oxidative kinetic resolution based on α-hydroxylation in the presence of a chiral guanidine-bisurea bifunctional organocatalyst. Benzylic oxidation of the tetralones at C1 followed by regioselective isomerization of the oxabenzonorbornadiene structure led to rishirilide B. Our findings lead to the revision of the previously proposed (2R,3R,4R) absolute configuration of (+)-rishirilide B to (2S,3S,4S).
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Affiliation(s)
- Minami Odagi
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Kota Furukori
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Kan Takayama
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Keiichi Noguchi
- Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan
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Castle SL. Total synthesis of the congested propellane alkaloid (-)-acutumine. CHEM REC 2014; 14:580-91. [PMID: 24863243 DOI: 10.1002/tcr.201400005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Indexed: 11/11/2022]
Abstract
The enantioselective total synthesis of (-)-acutumine is described. The synthetic strategy was inspired by the premise that the cyclohexenone ring could be derived from an aromatic precursor. After successful construction of a propellane model system, an initial attempt to prepare the spirocyclic subunit was thwarted by incorrect regioselectivity in a radical cyclization. A second-generation approach involving a radical-polar crossover reaction was successful, and the chemistry developed in the aforementioned model system was then applied to synthesize the natural product. Key reactions included a phenolic oxidation, a diastereoselective ketone allylation utilizing Nakamura's chiral allylzinc reagent, an anionic oxy-Cope rearrangement, an acid-promoted cyclization of a secondary amine onto an α,β-unsaturated ketal, and a regioselective methyl enol etherification of a 1,3-diketone.
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Affiliation(s)
- Steven L Castle
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602, USA.
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Wenderski TA, Hoarau C, Mejorado L, Pettus TRR. Dearomatization applications of I (III) reagents and some unusual reactivity amongst resorcinol derived cyclohexadienones. Tetrahedron 2010; 66:5873-5883. [PMID: 23750053 DOI: 10.1016/j.tet.2010.05.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The oxidative dearomatization of resorcinol derivatives, which are outfitted with a lactic acid derived chiral tether, and mitigated by hypervalent iodine derivatives of PhIO, affords stable chiral cyclohexadienones as useful building blocks for the construction of many highly functionalized chiral six and seven-membered ring systems. Herein, we report a multitude of remarkable and unexpected diastereoselective transformations stemming from these cyclohexadienone adducts.
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Affiliation(s)
- Todd A Wenderski
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA
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Li F, Tartakoff SS, Castle SL. Enantioselective total synthesis of (-)-acutumine. J Org Chem 2010; 74:9082-93. [PMID: 19904909 DOI: 10.1021/jo902006q] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An account of the total synthesis of the tetracyclic alkaloid (-)-acutumine is presented. A first-generation approach to the spirocyclic subunit was unsuccessful as a result of incorrect regioselectivity in a radical cyclization. However, this work spawned a second-generation strategy in which the spirocycle was fashioned via a radical-polar crossover reaction. This process merged an intramolecular radical conjugate addition with an enolate hydroxylation and created two stereocenters with excellent diastereoselectivity. The reaction was promoted by irradiation with a sunlamp, and a ditin reagent was required for aryl radical formation. These facts suggest that the substrate may function as a sensitizer, thereby facilitating homolytic cleavage of the ditin reagent. The propellane motif of the target was then installed via annulation of a pyrrolidine ring onto the spirocycle. The sequence of reactions used included a phenolic oxidation, an asymmetric ketone allylation mediated by Nakamura's chiral allylzinc reagent, an anionic oxy-Cope rearrangement, a one-pot ozonolysis-reductive amination, and a Lewis acid promoted cyclization of an amine onto an alpha,beta-unsaturated dimethyl ketal. Further studies of the asymmetric ketone allylation demonstrated the ability of the Nakamura reagent to function well in a mismatched situation. A TiCl(4)-catalyzed regioselective methyl enol etherification of a 1,3-diketone completed the synthesis.
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Affiliation(s)
- Fang Li
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA
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Sun BF, Hong R, Kang YB, Deng L. Asymmetric total synthesis of (-)-plicatic acid via a highly enantioselective and diastereoselective nucleophilic epoxidation of acyclic trisubstitued olefins. J Am Chem Soc 2009; 131:10384-5. [PMID: 19601599 DOI: 10.1021/ja9039407] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The first total synthesis of (-)-plicatic acid has been achieved by a concise and enantioselective route. In this synthesis, a conceptually new strategy featuring an asymmetric epoxidation-intramolecular epoxy-ring-opening Friedel-Crafts reaction sequence was developed for the stereoselective construction of the 2,7'-cyclolignane skeleton bearing contiguous quaternary-quaternary-tertiary stereocenters. The implementation of this strategy was enabled by the development of a modified protocol for the Seebach epoxidation with TADOOH, which affords an unprecedented, highly enantioselective and diastereoselective epoxidation with a range of alpha-carbonyl-beta-substituted acrylates 3.
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Affiliation(s)
- Bing-Feng Sun
- Department of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02454-9110, USA
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Wenderski TA, Huang S, Pettus TRR. Enantioselective total synthesis of all of the known chiral cleroindicins (C-F): clarification among optical rotations and assignments. J Org Chem 2009; 74:4104-9. [PMID: 19476394 DOI: 10.1021/jo900401k] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enantioselective syntheses of all of the named chiral members of the cleroindicin family (C-F) are reported. This effort demonstrates the synthetic utility of a 2,4-dihydroxybenzaldehyde as a starting material for natural product synthesis through the use sequential o-quinone methide chemistry and diastereoselective dearomatization. Natural cleroindicin F was shown to be nearly racemic, and an optically pure synthetic sample of cleroindicin F was found to racemize under slightly basic conditions. All other natural chiral cleroindicins are shown to be partially racemic.
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Affiliation(s)
- Todd A Wenderski
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, USA
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Mejorado LH, Pettus TRR. Total synthesis of (+)-rishirilide B: development and application of general processes for enantioselective oxidative dearomatization of resorcinol derivatives. J Am Chem Soc 2006; 128:15625-31. [PMID: 17147370 PMCID: PMC2561995 DOI: 10.1021/ja062987w] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A concise synthesis of (+)-rishirilide B (2) is described. This is the first synthesis to be reported for the (+)-enantiomer of rishirilide B (2) as found in nature. The strategy accentuates the valuable combination of a method for o-quinone methide coupling with a method for enantioselective resorcinol dearomatization, which provides a densely functionalized chiral building block. The convergent synthesis illustrates several improvements and refinements to these methods and their supporting chemistries. Among these is the in situ generation of PhI[OTMS]OTf. Combination of this oxidant with phenol 31 constitutes the first example of a diastereoselective oxidative dearomatization of a resorcinol displaying a 2-alkyl substituent. In addition, the preparation of the cyclic sulfone 34 is reported. As a new dimethide precursor expressing a readily cleavable O-benzyl residue, sulfone 34 should prove useful in future endeavors. A protocol using the aluminum amide of dimethylhydrazine for opening and cleavage of a [1,4]-dioxan-2-one is also described. This procedure unmasks the hydroxy dione 36 by jettisoning the chiral directing group. Regioselective O-carbamylation of the 1,3-dione 36 enables the transformation of the remaining carbonyl into the alpha-hydroxy carboxylic acid found in 2. The total synthesis of (+)-rishirilide B (2) requires 15 pots from benzaldehyde 17 and 13 pots from benzaldehyde 32. The final product emerges in yields of 12.5% and 20.3% from compounds 17 and 32, respectively. The longest linear sequence requires eight chromatographies. Important observations leading to the development of the principle asymmetric method are described within the context of the total synthesis.
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Affiliation(s)
- Lupe H. Mejorado
- Contribution from the Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, E-mail:
| | - Thomas R. R. Pettus
- Contribution from the Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, E-mail:
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