Enantioselective total synthesis of (+)-eupenoxide and (+)-phomoxide: Revision of structures and assignment of absolute configuration

Organic Letters

Volumn 6, Issue 14, 2004, Pages 2389-2392

  Mehta, Goverdhan ^a   Roy, Subhrangsu ^a  

^a INDIAN INSTITUTE OF SCIENCE   (India)

Author keywords

[No Author keywords available]

Indexed keywords

BENZOQUINONE DERIVATIVE; CYCLOPENTADIENE DERIVATIVE; EUPENOXIDE; PHOMOXIDE; POLYKETIDE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL REACTION; DIELS ALDER REACTION; ENANTIOSELECTIVITY; REACTION ANALYSIS; STEREOCHEMISTRY; STRUCTURE ANALYSIS; SYNTHESIS;

BENZOQUINONES; CATALYSIS; CYCLOPENTANES; HETEROCYCLIC COMPOUNDS, 2-RING; INDICATORS AND REAGENTS; MACROLIDES; MOLECULAR STRUCTURE; NUCLEAR MAGNETIC RESONANCE, BIOMOLECULAR; STEREOISOMERISM; XYLARIALES;

EID: 3242728831     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0492288     Document Type: Article

References (13)

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2. 1 reads "Quinn, R. J.; Rickards, R. W. Aust. J. Chem. 1984, in press."
3. Liu, Z.; Jensen, P. R.; Fenical, W. Phytochemistry 2003, 64, 571.
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9. Gemal, A. L.; Luche, J. L. J. Am. Chem. Soc. 1981, 103, 5454.
10. 3OH); 1H NMR (300 MHz, CD3OD) O 4.83 (d, J = 12.6Hz, IH), 4.69 (d, J= 12.6Hz, IH), 4.53 (d, J = 1.5Hz, IH), 4.40 (d, J= 1.5Hz, IH), 4.32 (d, J= 12.9Hz, IH), 4.17 (d, J = 12.9Hz, IH), 3.32-3.29 (m, 2H), 2.04 (s, 3H); 13C NMR (75 MHz, CD3OD) O 172.8, 137.4, 130.1, 64.8, 64.2, 62.2, 59.7, 53.8, 53.8, 20.8; HRMS (ES) ml z calcd for Ci0Hi4NaO6 [M + Na]+ 253.0688, found 253.0691. (-)-15: [a]23D -150.0 (c 0.58, CHCl3); 1H NMR (300 MHz, CDCl3) ô6.65-6.47 (m, 2H), 5.02 (br s, IH), 4.34 (s, 2H), 3.88-3.86 (m, IH), 3.49 (d, J = 3.6 Hz, IH), 2.30-2.22 (m, 2H), 1.52-1.28 (m, 6H), 0.90 (t, J = 6.6 Hz, 3H); 13C NMR (75 MHz, CDCl3) ô196.2, 149.1, 143.7, 129.4, 125.0, 63.0, 55.7, 55.5, 52.4, 34.0, 31.4, 28.4, 22.4, 14.0; HRMS (ES) ml z calcd for Ci4H20-NaO4 [M + Na]+ 275.1259, found 275.1244. (-)-16: [a]26D -167.02 (c 0.94, CHCl3); 1H NMR (300 MHz, CDCl3) ô6.69-6.56 (m, IH), 6.48 (d, ./ = 15.6 Hz, IH), 6.37 (s, IH), 6.25-6.17 (m, IH), 6.10-6.00 (m, IH). 5.04 (1/2ABq, J = 12.3 Hz, IH), 4.86 (1/2ABq, J = 12.3 Hz, IH), 3.76-3.74 (m, IH), 3.57 (d, J = 3.6 Hz, IH), 2.19-2.10 (m, 2H), 2.13 (s, 3H), 2.05 (s, 3H), 1.52-1.40 (m, 2H), 0.92 (t, J = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3) ô192.8, 170.8, 145.9, 143.6, 139.2, 130.5, 128.4, 124.2, 63.1, 56.4, 52.8, 51.9, 35.1, 22.0, 20.8, 20.8, 13.7; HRMS (ES) ml z calcd for Ci8H22NaO6 [M + Na]+ 357.1314, found 357.1295. 1: [cx]25D +20.0 (c 1.95, CHCl3); IR (cirr1) 3372; 1H NMR (300 MHz, CDCl3) ô6.29 (d. J = 15.9 Hz, JH), 6.15-6.05 (m, IH), 4.75 (s, IH), 4.59 (s, IH), 4.57 (d, J= 12.6 Hz, IH), 4.10 (d, ./ = 12.6 Hz, IH), 3.46 (br s, IH), 3.37 (br s, IH), 2.24-2.07 (m, 2H), 1.44-1.28 (m, 6H), 0.89 (t, J = 6.6 Hz, 3H); 13C NMR (75 MHz, CDCl3) see Table 1; HRMS (ES) ml z calcd for Ci4H22-NaO4 [M + Na]+ 277.1416, found 277.1407. 2: [a]25D +161.2 (c 1.16, CH3OH); IR (cm-1) 3377; 1H NMR (300 MHz, CDCl3) ô6.64-6.55 (m, IH), 6.35 (d, J = 15.3 Hz, IH), 6.17-6.09 (m, IH), 5.93-5.83 (m, IH), 4.77 (br s, IH), 4.58 (br s, IH), 4.53 (d, J= 12.6 Hz, IH), 4.09 (d, J = 12.6 Hz, IH), 3.45 (br s, IH), 3.35 (br s, IH), 2.15-2.08 (m, 2H), 1.50-1.37 (m, 2H), 0.92 (t, J = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3) see Table 2; HRMS (ES) ml z calcd for Cj4H20NaO4 [M + Na]+ 275.1259, found 275.1246. 3: [cx]24D +1.8 (c 1.15, CH3OH); IR (cm-1): 3387; 1H NMR (300 MHz, CDCl3) ô6.28 (d, J = 15.9 Hz, IH), 6.08-5.99 (m, IH), 4.72 (br s, 2H), 4.40 (br s, 2H), 3.48 (s, 2H), 2.16-2.12 (m, 2H), 1.44-1.29 (m, 6H), 0.89 (t, J = 6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3) see Table 1; HRMS (ES) ml z calcd for Ci4H22NaO4 [M + Na]+ 277.1416, found 277.1410. 4: [cx]24D +18.3 (c 0.71, CH3OH); IR (cm'1) 3392; 1H NMR (300 MHz, CDCl3 + CD3OD) ô6.56-6.48 (m, IH), 6.36 (d, J = 15.6 Hz, IH), 6.14-6.06 (m, IH), 5.84-5.74 (m, IH), 4.69 (br s, IH), 4.66 (br s, IH), 4.38 (br s, 2H), 3.50 (s, 2H), 2.10-2.03 (m, 2H), 1.45-1.33 (m, 2H), 0.87 (t, J = 7.2 Hz, 3H); 13C NMR (75 MHz, CDCl3 + CD3OD) see Table 2; HRMS (ES) ml z calcd for Ci4H20KO4 [M + K]+ 291.0999, found 291.1001.
11. Semmelhack, M. F.; Schmid, C. R.; Cortes, D. A.; Chou, C. S. J. Am. Chem. Soc. 1984, 106, 3374.
12. 3).
13. 3), in the absence of the optical rotation data on the natural product, its absolute configuration has been projected through extrapolation on the basis of the deductions on phomoxide (vide infra). Consequently, (+)-3 obtained by us is ent-eupenoxide and structure 3 represents the absolute configuration of the natural product.