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  • 1
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, VI. Substratkontrollierte asymmetrische Synthese von (3aS,6aR)-(+)-3,3a,6,6a-Tetrahydro-2H-cyclopenta[b]furan-2-on (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 811-814 
    Details
    ISSN: 0170-2041
    Keywords: Cyclopenta[b]furan-2-one, (3aS,6aR)-(+)-3,3a,6,6a-tetrahydro-2H- ; Radicals ; Cyclization ; Carvone ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dienes, VI. - Substrate-Controlled Asymmetric Synthesis of (3aS,6aR)-(+)-3,3a,6,6a-Tetrahydro-2H-cyclopenta[b]furan-2-one(R)-(-)-Carvone (1) was converted via straightforward reactions into 10-hydroxycarvone (4) which was cyclized to 5 via the mercury-mediated free-radical method. Periodate cleavage of 5 yields the bicyclic dione 6. Regio- and stereoselective reduction of 6 with lithium tri(tert-butyloxy)hydridoaluminate results in 7 (80% yield). 7 was directly converted into γ-lactone 8 via Baeyer-Villiger oxidation. Saponification of 8 to 9, mesylation of 9 to 10 followed by elimination of methanesulfonic acid yield enantiomerically pure (3aS,6aR)-(+)-3,3a,6,6a-Tetrahydro-2H-cyclopenta[b]furan-2-one (11). The synthesis can be carried out with readily available, and economical, (S)-(+)-carvone to yield ent-11.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301128
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  • 2
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, VI. Totalsynthese von (-)-Coriolin und (-)-Epicoriolin aus (S)-(+)-Carvon (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1133-1140 
    Details
    ISSN: 0170-2041
    Keywords: (-)-Coriolin ; (-)-Epicoriolin ; Radicals ; Cyclization ; Triquinans ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dines, VI. - Total Synthesis of (-)-Coriolin and (-)-Epicoriolin from (S)-(+)-Carvone(3aR,4S,6aS)-(+)-4-(4-Methoxybenzyloxy)-6a-methyl-3,3a,4,6a-tetrahydro-2H-cyclopenta[b]furan-2-one (10) and (3aR,3bR,4R,6aS,7S,7aS)-(-)-decahydro-4,7-dihydroxy-3a,5,5-trimethyl-3-methylene-2H-cyclopenta[a]pentalen-2-one (21) are the key intermediates in the synthesis of the title compounds 1 and 1a. Enantiomerically pure 10 is produced from (S)-(+)-carvone (4) in seven straightforward reactions. Compound 21 is produced from 10 by analogy with the method developed for the synthesis of (-)-hirsutene. Through the introduction of the double bond into 21 via the silylenolether 23 one arrives at precoriolin 25, which is converted into (-)-coriolin (1) and the C-3 epimer (-)-epicoriolin (1a) (63:37) with hydrogen peroxide. The structures of 1 and 1a were confirmed via X-ray crystallography.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1993199301181
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  • 3
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, V. Substratkontrollierte asymmetrische Synthese von (-)-Hirsuten und (-)-3-Hydroxyhirsuten aus (R)-(-)-Carvon (1993)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 403-411 
    Details
    ISSN: 0170-2041
    Keywords: Hirsutene derivatives ; Cyclopenta[a]pentalenes ; Radicals ; Cyclizations ; Triquinanes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dienes, V. - Substrate-Controlled Asymmetric Synthesis of (-)-Hirsutene and (-)-3-Hydroxyhirsutene from (R)-(-)-Carvone(3aR,6aR)-(-)-6a-Methyl-3,3a,4,6a-tetrahydro-2H-cyclopenta- [b]furan-2-one (6) and (1R,4S)-(-)-3-[4-(but-3-inyl)-3-methyl-cyclopent-2-enyl]-2,2-dimethylpropan-1-ol (11) are key compounds in the synthesis reported in this paper. Enantiomerically pure 6 was obtained in five straightforward steps from the inexpensive precursor (R)-(-)-carvone (1). Compound 11 was prepared from 6 via an SN2′ reaction, by analogy with the synthesis reported by Curran et al. The linear triquinanes 13 and 15 were obtained in gram quantities in two additional steps. The utilisation of (S)-(+)-carvone (ent-1) allows access to the other enantiomeric forms. X-ray analysis of 15a confirmed the structure of 15 and, by correlation, that of 13.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199319930166
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  • 4
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, IX. Über die Stereoselektivität der radikalischen 4-exo-trig-Cyclisierung von optisch aktiven (2E)-6-Oxohex-2-ensäureestern mit Samarium(II)-iodid (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1305-1309 
    Details
    ISSN: 0009-2940
    Keywords: Radicals ; Cyclobutanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dienes, IX. - On the Stereoselectivity of the Radical 4-exo-trig-Cyclization of Optically Active Ethyl (2E)-6-Oxohex-2-enoates with Samarium(II) IodideEthyl (5R, 2E)-5-(benzyloxy)-4,4-dimethyl-6-oxohex-2-enoate (9) was prepared from (R)-(-)-pantolactone (3) by a series of straightforward reactions. The reaction of 9 with samarium(II) iodide produces enantiomerically pure ethyl (1S,3R,4R)-(-)-[3-(benzyloxy)-4-hydroxy-2,2-dimethylcyclo-butyl]acetate (10) in 60% yield. The absolute configuration at C-1 and C-3 was confirmed by the conversion of 10 to the crystalline 15a, whose absolute configuration is known from its synthesis from (1S,5S)-( + )-α-pinene (12). The configuration of the hydroxy group at C-4 in 10 was determined from NOE studies on the epimiric 17. The radical 4-exo-trig-cyclization of optically active (2E)-6-oxohex-2-enoates with samarium(II) iodide opens a new pathway to enantiomerically pure cyclobutanol and cyclobutanone derivatives, which are of interest as building blocks in natural products synthesis.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270720
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  • 5
    Electronic Resource
    Electronic Resource
    Radikalische Cyclisierung von Dienen, VIII. Über die regioselektive Herstellung von ungesättigten Cyclopenta[b]furan-2-onen aus (S)-(+)-Carvon  -  Bausteine zur Synthese von enantiomerenreinen Triquinanen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 549-550 
    Details
    ISSN: 0009-2940
    Keywords: Radicals ; Cyclization ; Triquinanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical-Type Cyclization of Dienes, VIII[1].  -  On the Regioselective Synthesis of Unsaturated Cyclopenta[b]furan-2-ones from (S)-(+)-Carvone  -  Building Blocks for the Synthesis of Enantiomerically Pure TriquinanesThe diastereomeric products 2a and 2b, which were synthesized from (S)-(+)-carvone (1), are converted to (3aS,5S,6aS)-(-)-5-acetoxyhexahydro-6a-methyl-2H-cyclopenta[b]furan-2-one (4) in ca. 50% yield. 4 is regioselectively converted to (3aR,6aS)-(-)-3,3a,6,6a-tetrahydro-6a-methyl- (8a) and (3aS,6aR)-(+)-3,3a,4,6a-tetrahydro-6a-methyl-2H-cyclopenta[b]-furan-2-one (8b). These are used at the 10-g scale for the synthesis of enantiomerically pure triquinanes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270314
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