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Pastor A, Prinsloo R, Burford KN, Macdonald AR, Parvez M, Gendy C, Back TG. Synthesis of the Marine Alkaloid Cylindricine C and Serendipitous Synthesis of Its 2,13-Di- epi Stereoisomer. J Org Chem 2023; 88:13813-13824. [PMID: 37722076 DOI: 10.1021/acs.joc.3c01467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
A new approach to the marine alkaloid cylindricine C afforded its previously unreported (±)-2,13-di-epi stereoisomer as the major product along with a minor amount of the racemic parent alkaloid. Key steps included a stereoselective dianion alkylation of a monoester of 1,2-cyclohexanedicarboxylic acid and an annulation based on the tandem conjugate addition of a primary amine to an acetylenic sulfone, followed by intramolecular acylation of the resulting sulfone-stabilized carbanion. The cis-azadecalin moiety thus formed, comprising the cyclohexane A-ring and enaminone B-ring of the products, was further elaborated by the selenenyl chloride-induced cyclofunctionalization of a pendant butenyl substituent with the enaminone moiety, followed by a seleno-Pummerer reaction. Desulfonylation and enaminone reduction afforded the final products. Molecular modeling and X-ray crystallography provided further insight into these processes.
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Affiliation(s)
- Arnaud Pastor
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Rohen Prinsloo
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Kristen N Burford
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Andrew R Macdonald
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Masood Parvez
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Chris Gendy
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Thomas G Back
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
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Hanzawa R, Fuwa H. Collective Asymmetric Total Synthesis of Cylindricines. Org Lett 2023; 25:1984-1988. [PMID: 36912364 DOI: 10.1021/acs.orglett.3c00551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Collective asymmetric total synthesis of marine tricyclic alkaloids, cylindricines A-H, and the proposed structures of cylindricines I and J was achieved in a concise manner from a single common spirocyclic pyrrolidine intermediate. A tandem chemoselective oxidation/intramolecular aza-Michael addition/epimerization was exploited to complete the tricyclic skeleton. This work provides a versatile synthetic entry to the cylindricine family of marine tricyclic alkaloids.
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Affiliation(s)
- Ryohei Hanzawa
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
| | - Haruhiko Fuwa
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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Abstract
Starting from (R)-phenylglycinol-derived tricyclic lactam 1, the enantioselective synthesis of (-)-cylindricine H is reported. From the stereochemical standpoint, the key steps are the stereoselective generation of the quaternary C10 stereocenter, the stereoselective introduction of the C4 acetoxy and C2 butyl substituents taking advantage of the lactam carbonyl functionality, and the assembly of the pyrrolidine ring with the required functionalized one-carbon chain at C13 by intramolecular opening of an epoxide.
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A flexible enantioselective approach to 2,5-disubstituted cis-decahydroquinolines. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.132935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wang XG, Ou W, Liu MH, Liu ZJ, Huang PQ. Tandem Catalysis Enabled Highly Chemoselective Deoxygenative Alkynylation and Alkylation of Tertiary Amides: A Versatile Entry to Functionalized α-Substituted Amines. Org Chem Front 2022. [DOI: 10.1039/d2qo00335j] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here the highly chemoseive catalytic reductive alkynylation and reductive alkylation of tertiary amides to give propargylamines and α-branched amines, respectively. The method features a tandem iridium (Vaska’s complex)-catalyzed...
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