1
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Zheng J, Wu X, Li WDZ. A model study for the total synthesis of lophotoxin. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.153481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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2
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Wang Y, Huang G, Shi Y, Tian WS, Zhuang C, Chen FE. Asymmetric synthesis of (-)-solanidine and (-)-tomatidenol. Org Biomol Chem 2020; 18:3169-3176. [PMID: 32270168 DOI: 10.1039/d0ob00457j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A concise asymmetric synthesis of two naturally occurring seco-type cholestane alkaloids (-)-solanidine and (-)-tomatidenol from (-)-diosgenin with a linear reaction sequence of 12 steps and 13 steps, respectively, is reported. The synthetic strategy includes the highly controlled establishment of highly functionalized octahydroindolizine ((-)-solanidine) and 1-oxa-6-azaspiro[4.5]decane ((-)-tomatidenol) cores with five stereocenters, respectively, from (-)-diosgenin, featuring two stereoselective cascade transformations including a modified cascade ring-switching process of furostan-26-acid to open the E-ring of (-)-diosgenin and a cascade azide reduction/intramolecular reductive amination to close the E- and F-rings of (-)-solanidine and (-)-tomatidenol. This work should enable further explorations of chemical and biological spaces based on solanidine, tomatidenol and related natural products.
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Affiliation(s)
- Yun Wang
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China. and Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China
| | - Guanxin Huang
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China.
| | - Yong Shi
- Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Wei-Sheng Tian
- Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Chunlin Zhuang
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China. and Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China
| | - Fen-Er Chen
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China. and Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China and Institute of Pharmaceutical Science and Technology, Zhejiang University of Technology, 18 Chao Wang Road, 310014, Hangzhou, China
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3
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Wang Y, Shi Y, Tian WS, Tang P, Zhuang C, Chen FE. Stereoselective Synthesis of (-)-Verazine and Congeners via a Cascade Ring-Switching Process of Furostan-26-acid. Org Lett 2020; 22:2761-2765. [PMID: 32202118 DOI: 10.1021/acs.orglett.0c00747] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An efficient synthetic strategy for three natural seco-type cholestane alkaloids isolated from the Veratrum plants, based on commercially available naturally occurring and abundant (-)-diosgenin (1), as exemplified in the concise asymmetric synthesis of (-)-verazine (4), (-)-veramiline (5) (proposed structure), and its 22-epimer, (-)-oblonginine (6), is presented. This work highlights the application of a cascade ring-switching process of (-)-diosgenin to achieve the E-ring opening and construction of chiral six-membered lactone challenges in seco-type cholestane alkaloid synthesis. This approach enables the synthesis of related natural and nature-like novel cholestane alkaloids, opening up opportunities for more extensive exploration of cholestane alkaloid biology.
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Affiliation(s)
- Yun Wang
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China.,Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China
| | - Yong Shi
- Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Wei-Sheng Tian
- Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Pei Tang
- West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Chunlin Zhuang
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China.,Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China
| | - Fen-Er Chen
- Engineering Center of Catalysis and Synthesis for Chiral Molecules, Fudan University, Shanghai 200433, China.,Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs, Shanghai 200433, China.,West China School of Pharmacy, Sichuan University, Chengdu 610041, China
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4
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Zhou J, Wu Z, Oyawaluja BO, Coker HAB, Odukoya OA, Yao G, Che CT. Protein Tyrosine Phosphatase 1B Inhibitory Iridoids from Psydrax subcordata. JOURNAL OF NATURAL PRODUCTS 2019; 82:2916-2924. [PMID: 31618031 DOI: 10.1021/acs.jnatprod.9b00770] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phytochemical investigation of the leaves and bark of Psydrax subcordata has led to the isolation of six new iridoids, subcordatanols I-V (1-4 and 6) and 1-O-methylcrescentin I (5), along with two known analogues (7 and 8). Among them, subcordatanol I (1) is the first example of a 3,8-monoepoxy-iridoid featuring a caged 2-oxa-bicyclo[3.2.1]octane core. The absolute stereochemistry at C-4 of 3, 4, and 6 was established through their acid-catalyzed reaction products subcordatalactones A (3a), B (4a), and C (6a), respectively. Subcordatanols I (1) and II (2), as well as subcordatalactones A (3a) and B (4a), displayed inhibitory activity against protein tyrosine phosphatase 1B (PTP1B). Enzyme kinetic studies indicated that 3a and 4a are competitive inhibitors. A molecular docking study is also reported.
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Affiliation(s)
- Junfei Zhou
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Illinois at Chicago , Chicago , Illinois 60612 , United States
| | - Zhenlong Wu
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Illinois at Chicago , Chicago , Illinois 60612 , United States
- Institute of Traditional Chinese Medicine & Natural Products, College of Pharmacy , Jinan University , Guangzhou 510632 , People's Republic of China
| | - Bamisaye O Oyawaluja
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Illinois at Chicago , Chicago , Illinois 60612 , United States
| | | | | | - Guangmin Yao
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College , Huazhong University of Science and Technology , Wuhan 430030 , People's Republic of China
| | - Chun-Tao Che
- Department of Pharmaceutical Sciences, College of Pharmacy , University of Illinois at Chicago , Chicago , Illinois 60612 , United States
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5
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Weber F, Becker F, Keller M, Hillebrecht H, Brückner R. Aldol Additions of Titanium and Boron Enolates of Achiral and Chiral δ-Lactones to Achiral Model Aldehydes: Simple and Induced Diastereoselectivities. European J Org Chem 2015. [DOI: 10.1002/ejoc.201501128] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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6
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Amat M, Guignard G, Llor N, Bosch J. Access to enantiopure 4-substituted 1,5-aminoalcohols from phenylglycinol-derived δ-lactams: synthesis of Haliclona alkaloids. J Org Chem 2014; 79:2792-802. [PMID: 24555853 DOI: 10.1021/jo5002627] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
LiNH2BH3-promoted reductive opening of 8-substituted phenylglycinol-derived oxazolopiperidone lactams leads to enantiopure 4-substituted-5-aminopentanols, which are used as starting building blocks in the synthesis of the Haliclona alkaloids haliclorensin C, haliclorensin, and halitulin (formal). The starting lactams are easily accessible by a cyclocondensation reaction of (R)-phenylglycinol with racemic γ-subtituted δ-oxoesters, in a process that involves a dynamic kinetic resolution.
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Affiliation(s)
- Mercedes Amat
- Laboratory of Organic Chemistry, Faculty of Pharmacy, and Institute of Biomedicine (IBUB), University of Barcelona , 08028 Barcelona, Spain
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7
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Zhu L, Song L, Tong R. Diastereoselective Reductive Ring Expansion of Spiroketal Dihydropyranones to cis-Fused Bicyclic Ethers. Org Lett 2012; 14:5892-5. [DOI: 10.1021/ol302813e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Liangyu Zhu
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Liyan Song
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Rongbiao Tong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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8
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Lacey MJ, Sémon E, Krasulová J, Sillam-Dussès D, Robert A, Cornette R, Hoskovec M, Záček P, Valterová I, Bordereau C. Chemical communication in termites: syn-4,6-dimethylundecan-1-ol as trail-following pheromone, syn-4,6-dimethylundecanal and (5E)-2,6,10-trimethylundeca-5,9-dienal as the respective male and female sex pheromones in Hodotermopsis sjoestedti (Isoptera, Archotermopsidae). JOURNAL OF INSECT PHYSIOLOGY 2011; 57:1585-1591. [PMID: 21839084 DOI: 10.1016/j.jinsphys.2011.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/26/2011] [Accepted: 07/27/2011] [Indexed: 05/31/2023]
Abstract
The trail-following pheromone and sex pheromones were investigated in the Indomalayan termite Hodotermopsis sjoestedti belonging to the new family Archotermopsidae. Gas chromatography coupled to mass spectrometry (GC-MS) after solid phase microextraction (SPME) of the sternal gland secretion of pseudergates and trail-following bioassays demonstrated that the trail-following pheromone of H. sjoestedti was syn-4,6-dimethylundecan-1-ol, a new chemical structure for termite pheromones. GC-MS after SPME of the sternal gland secretion of alates also allowed the identification of sex-specific compounds. In female alates, the major sex-specific compound was identified as (5E)-2,6,10-trimethylundeca-5,9-dienal, a compound previously identified as the female sex pheromone of the termite Zootermopsis nevadensis. In male alates, the major sex-specific compound was identified as syn-4,6-dimethylundecanal, a homolog of syn-4,6-dimethyldodecanal, which has previously been confirmed as the male sex pheromone of Z. nevadensis. The presence of sex-specific compounds in alates of H. sjoestedti strongly suggests for this termite the presence of sex-specific pairing pheromones which were only known until now in Z. nevadensis. Our results showed therefore a close chemical relationship between the pheromones of the taxa Hodotermopsis and Zootermopsis and, in contrast, a clear difference with the taxa Stolotermes and Porotermes, which is in total agreement with the recent creation of the families Archotermopsidae and Stolotermitidae as a substitute for the former family Termopsidae.
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Affiliation(s)
- Michael J Lacey
- CSIRO Ecosystem Sciences, G.P.O. Box 1700, Canberra, ACT 2601, Australia
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9
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Ghostin J, Bordereau C, Braekman J. Synthesis ofsyn-4,6-dimethyldodecanal, the male sex pheromone and trail-following pheromone of two species of the termiteZootermopsis. Nat Prod Res 2011; 25:560-8. [DOI: 10.1080/14786419.2010.535152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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10
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Matsuo JI, Sasaki S, Hoshikawa T, Ishibashi H. Diels–Alder reaction of eight-membered cyclic siloxydienes. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.09.053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Das I, Suresh CG, Décout JL, Pathak T. Unusual addition of amines to C-2 of vinyl sulfone-modified-β-d-pent-2-enofuranosyl carbohydrates: synthesis of a new class of β-anomeric 2-amino-2,3-dideoxy-d-threo-pentofuranosides. Carbohydr Res 2008; 343:1287-96. [DOI: 10.1016/j.carres.2008.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 03/06/2008] [Accepted: 03/13/2008] [Indexed: 10/22/2022]
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12
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13
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Das I, Pathak T. Desulfonylation with Mg−MeOH−NiBr2: An Expedient Reagent System for the Synthesis of 2-Amino-2,3-dideoxy Furanosides. Org Lett 2006; 8:1303-6. [PMID: 16562877 DOI: 10.1021/ol053082a] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] A catalytic amount of NiBr(2) with Mg-MeOH increases the efficiency of reductive desulfonylation of the beta-sulfonylated aminosugars. The Mg-MeOH-NiBr(2) system has been utilized in the synthesis of 2-amino-2,3-dideoxypentofuranosides and 2-amino-2,3-dideoxyhexofuranosides. The yield of the desulfonylation improved dramatically from 0% with the known reagents to 44-75% with Mg-MeOH-NiBr(2).
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Affiliation(s)
- Indrajit Das
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India
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14
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Betancor C, Freire R, Pérez-Martín I, Prangé T, Suárez E. Hydrogen atom transfer methodology for the synthesis of C-22, C-23, and C-25 stereoisomers of cephalostatin north 1 side chain from spirostan sapogenins. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.01.077] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Yang Z, Wong ELM, Shum TYT, Che CM, Hui Y. Fluorophore-Appended Steroidal Saponin (Dioscin and Polyphyllin D) Derivatives. Org Lett 2005; 7:669-72. [PMID: 15704921 DOI: 10.1021/ol0475616] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of three fluorophore-appended derivatives of dioscin and polyphyllin D is reported herein. Starting from trillin, dansyl derivatives A-C were prepared in overall yields of 7-12% over 7-10 steps. A study of their behavior in a variety of polar solvents suggests that dansyl derivatives A-C are capable of micellar self-assembly and can maintain cytotoxicities (IC50 = 15-18 muM) against the HeLa carcinoma cell line evaluated by standard MTT assay. [structure: see text]
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Affiliation(s)
- Zhiqi Yang
- Shanghai-Hong Kong Joint Laboratory on Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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16
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Hilty F, Brun K, Heimgartner H. A New 2H-Azirin-3-amine as a Synthon for?-Methyl Glutamate. Helv Chim Acta 2004. [DOI: 10.1002/hlca.200490226] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Streiff S, Ribeiro N, Désaubry L. Unexpected cleavage of tetrahydrofuran by catalytic reductive lithiation. Chem Commun (Camb) 2004:346-7. [PMID: 14740070 DOI: 10.1039/b312972a] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Stéphane Streiff
- UMR 7509, Centre de Neurochimie, 5 rue Blaise Pascal, 67084 Strasbourg Cedex, France
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18
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Wang S, Kayser MM, Jurkauskas V. Access to optically pure 4- and 5-substituted lactones: a case of chemical-biocatalytical cooperation. J Org Chem 2003; 68:6222-8. [PMID: 12895054 DOI: 10.1021/jo026605q] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Optically pure or highly enantiomerically enriched 4- and 5-substituted lactones are rather difficult to obtain. Chemical or enzymatic syntheses alone are not particularly successful. A combination of chemical catalysis and biocatalysis, however, provides a convenient route to a variety of these useful chiral compounds. In this paper we describe the synthesis of several optically pure 4- and 5-substituted lactones obtained via whole cell-catalyzed Baeyer-Villiger oxidations of highly enantiomerically enriched 3-alkyl cyclic ketones. Such chiral ketones are readily accessed by recently developed copper-catalyzed asymmetric conjugate reductions of the corresponding enones. A very high proximal regioselectivity and complete chirality transfer was obtained by employing biological Baeyer-Villiger oxidations, using recombinant E. coli strains that overexpress cyclopentanone monooxygenase (CPMO). A comparative study showed that CPMO gives superior results to those obtained with cyclohexanone monooxygenase (CHMO) catalyzed oxidations.
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Affiliation(s)
- Shaozhao Wang
- Department of Physical Sciences, University of New Brunswick, Saint John, NB E2L 4L5, Canada
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Betancor C, Freire R, Pérez-Martín I, Prangé T, Suárez E. A convenient synthesis of C-22 and C-25 stereoisomers of cephalostatin north 1 side chain from spirostan sapogenins. Org Lett 2002; 4:1295-7. [PMID: 11950346 DOI: 10.1021/ol025580e] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A simple transformation of the eight-carbon side chain of a natural spirostan sapogenin into the cephalostatin north 1 spiroketal moiety is described. This methodology, based on an intramolecular hydrogen abstraction reaction promoted by alkoxy radicals, permits the synthesis of C-22 and C-25 stereoisomers of the dioxaspiro[4.4]nonane cephalostatin ring system. The acid-catalyzed isomerization of the spirocenter in the different isomers is studied. [reaction: see text]
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Affiliation(s)
- Carmen Betancor
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Carretera de La Esperanza 3, 38206 La Laguna, Tenerife, Spain
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Crich D, Dudkin V. Confirmation of the connectivity of 4,8,12,16,20-pentamethylpentacosylphoshoryl beta-D-mannopyranoside, an unusual beta-mannosyl phosphoisoprenoid from Mycobacterium avium, through synthesis. J Am Chem Soc 2002; 124:2263-6. [PMID: 11878980 DOI: 10.1021/ja0123958] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of the title glycolipid is reported. Comparison of the electrospray and high-energy collision-induced dissociation mass spectra of the synthetic material with those reported for the isolate confirm the structure of this unusual antigenic substance with its modified isoprenoid chain.
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Affiliation(s)
- David Crich
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA
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21
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Lee S, LaCour TG, Lantrip D, Fuchs PL. Redox refunctionalization of steroid spiroketals. Structure correction of ritterazine M. Org Lett 2002; 4:313-6. [PMID: 11820867 DOI: 10.1021/ol0165894] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structure of the North spiroketal moiety of ritterazine M has been corrected from 1a to 1b. This was accomplished by comparison of published spectra of the natural product with five synthetic spiroketal-alcohols. Synthesis of these models was efficiently accomplished by reductive cleavage of the spiroketal and Sharpless asymmetric dihydroxylation of an isopentyl, methyl 1,1-disubstituted olefin, followed by Suarez iodine[III] oxidative spirocyclization of monoprotected 1 degree,3 degree 1,2 diols.
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Affiliation(s)
- Seongmin Lee
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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22
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Cohen T, Kreethadumrongdat T, Liu X, Kulkarni V. Use of aromatic radical-anions in the absence of THF. Tandem formation and cyclization of benzyllithiums derived from the attack of homo- and bishomoallyllithiums on alpha-methylstyrenes: two-pot synthesis of cuparene. J Am Chem Soc 2001; 123:3478-83. [PMID: 11472119 DOI: 10.1021/ja004353+] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
When a homo- or bishomoallyllithium, generated by reductive lithiation of the corresponding phenyl thioether by the radical anion lithium 1-(dimethylamino)naphthalenide (LDMAN), is added to alpha-methylstyrene, a tandem addition/cyclization to a phenyl-substituted five- or six-membered-ring occurs. The yields are compromised by polymerization of the alpha-methylstyrene, a process favored by tetrahydrofuran (THF), the solvent used to generate lithium aromatic radical anions. Thus, a new method of generating LDMAN (unsuccessful for other common radical anions) in the absence of THF has been developed. The radical anion can be generated and the reductive lithiation performed in dimethyl ether at -70 degrees C. After the addition of diethyl ether or other solvent, and evaporation of the dimethyl ether in vacuo, the alpha-methylstyrene is added and the solution is warmed to -30 degrees C. When the unsaturated alkyllithium is primary, no adduct forms in THF due to polymerization of the alpha-methylstyrene, but moderate yields are attained in a solvent containing mainly hexanes. It was also found that the cyclized organolithiums, which would have become protonated in the presence of THF, can be captured by an electrophile, even at ambient temperature. A two-pot synthesis, the most efficient reported, of the sesquiterpene (+/-)-cuparene in 46% yield, using this technology is reported.
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Affiliation(s)
- T Cohen
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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24
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Mitsuhashi S, Shima H, Kawamura T, Kikuchi K, Oikawa M, Ichihara A, Oikawa H. The spiroketals containing a benzyloxymethyl moiety at C8 position showed the most potent apoptosis-inducing activity. Bioorg Med Chem Lett 1999; 9:2007-12. [PMID: 10450971 DOI: 10.1016/s0960-894x(99)00309-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The spiroketals containing a benzyloxymethyl moiety at the C8 position showed the most potent apoptosis-inducing activity, whereas its analogous compounds lacking any substituent at C8 or possessing ones other than the benzyloxymethyl moiety at C8 were all much less active. These results strongly suggest an important role of the benzyloxymethyl moiety linked to the C8 oxygen atom.
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Affiliation(s)
- S Mitsuhashi
- Institute of Immunological Science, Hokkaido University, Sapporo, Japan
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25
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Betancor C, Dorta RL, Freire R, Martín A, Prangé T, Suárez E. Stereospecific Synthesis of 1,6-Dioxadecalins and 2,2'-Linked Ditetrahydrofurans by Rearrangement of Steroidal Spiroacetals. J Org Chem 1998; 63:6355-6362. [PMID: 11672270 DOI: 10.1021/jo980834o] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reduction of steroidal spiroacetal methanesulfonate derivatives, containing the 1,6-dioxaspiro[4.5]decan-10-yl ring system, with DIBALH promotes a new rearrangement to give steroidal 1,6-dioxadecalin (octahydropyrano[3,2-b]pyran) or 2,2'-linked ditetrahydrofuran (octahydro[2,2']bifuranyl) derivatives. To study the scope and selectivity of the reaction, several steroidal spiroacetals such as (23R,25R)-3beta-methoxy-5alpha-spirostan-23-yl methanesulfonate (2) and its 23S-isomer (5) and (22R,23R,25R)-3beta-acetoxy-16beta,23:23,26-diepoxycholest-5-en-22-yl methanesulfonate (15) and its 22S-isomer (19) have been synthesized. Compound 2 was rearranged with absolute regio- and stereoselectivity to give (22S,23S,25R)-3beta-methoxy-16beta,23:22,26-diepoxy-5alpha-cholestane (3) which possesses a cis-fused 1,6-dioxadecalin ring system. The reaction of compound 5 gave exclusively (22S,23R,25R)-3beta-methoxy-23,26-epoxy-5alpha-furostane (6) in which the spiroacetal was converted into a ditetrahydrofuran subunit. The two other isomeric spiroacetals 15 and 19 were also mainly transformed into (22S,23S,25R)-3beta-acetoxy-16beta,23:22,26-diepoxycholest-5-ene (16) and (22R,23R,25R)-3beta-acetoxy-23,26-epoxyfurost-5-ene (20), respectively. A mechanism is proposed to explain the regio- and sterospecificity observed in the rearrangement.
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Affiliation(s)
- Carmen Betancor
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Carretera de La Esperanza 3, 38206-La Laguna, Tenerife, Spain, Instituto de Bio-Orgánica, Universidad de La Laguna, Tenerife, Spain, and LURE, Université Paris-Sud, Paris, 91405 ORSAY, Cedex, France
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Dorta RL, Martín A, Suárez E, Betancor C. Serendipitous Acid-Catalyzed Rearrangement of 13-Methoxy- 1,6,8-trioxadispiro[4.1.5.3]pentadecane to 3-Chroman-5-ylpropan-1-ol. J Org Chem 1997; 62:2273-2274. [PMID: 11671542 DOI: 10.1021/jo962065j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rosa L. Dorta
- Departamento de Química Orgánica, Universidad de La Laguna, Tenerife, Spain
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Dorta RL, Freire R, Martín A, Suárez E, Prangé T. Cis- and trans-fused Di-tetrahydropyrans by rearrangement of steroidal spiroacetals. Tetrahedron Lett 1995. [DOI: 10.1016/0040-4039(95)01472-t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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