Synlett 2009(19): 3099-3102  
DOI: 10.1055/s-0029-1218301
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Thieme Chemistry Journal Awardees - Where are They Now? Synthesis of the Marine Glycolipid Dioctadecanoyl Discoside

Gordon J. Florence*a, Tashfeen Aslama, Gavin J. Millera, Gavin D. S. Milnea, Stuart J. Conway*b
a Centre for Biomolecular Sciences, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
Fax: +44(1334)463808; e-Mail: gjf1@st-andrews.ac.uk;
b Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
Fax: +44(1865)285002; e-Mail: stuart.conway@chem.ox.ac.uk;
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Publikationsverlauf

Received 1 August 2009
Publikationsdatum:
21. Oktober 2009 (online)

Abstract

The first synthesis of the inositol-containing marine glycolipid dioctadecanoyl discoside is reported. The key glycosylation reaction proceeds with β-selectivity at reduced temperature. The separable anomers could be readily progressed to afford discoside, its peracetate and the unnatural β-derivatives.

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The ¹H NMR of 3 in 1% CD3OD/CDCl3 gave a broad, unresolved spectrum. Selected data for 3: Amorphous colourless solid; mp 110-115 ˚C; ¹H NMR (400 MHz, 1% CD3OD/CDCl3): δ = 5.40-4.90 (m, 4 H), 4.50-3.30 (m, 8 H), 2.40-2.10 (m, 4 H, H-2′′ and H-2′′′), 1.65-1.40 (m, 4 H, H-3′′ and H-3′′′), 1.20 (s, 56 H, 28 × CH2-lipid), 0.85-0.75 (m, 6 H, H-18′′ and H-18′′′); LRMS (MALDI-TOF):
m/z (%) = 897.9 (20) [M + Na]+, 453.5 (100).

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Data for α-peracetate 14: Oil; R f = 0.46 (PE-EtOAc, 6:4); [α]D ²0 +11.3 (c 0.73 CHCl3) (Lit.³ +12.0, c 0.5 CHCl3); IR (neat): 2918.2, 2850.3, 1753.2, 1369.3, 1225.2, 1043.9 cm; ¹³C NMR (400 MHz, CDCl3): δ = 5.53 (dd, J = 10.3, 10.2 Hz, 1 H, H-4), 5.50 (dd, J = 10.4, 9.6 Hz, 1 H, H-6), 5.43-5.40 (m, 2 H, H-3′ and H-4′), 5.38-5.36 (m, 1 H, H-2′), 5.19 (t, J = 9.6 Hz, 1 H, H-5), 5.09 (dd, J = 10.4, 2.4 Hz, 1 H, H-3), 5.00 (dd, J = 10.8, 2.8 Hz, 1 H, H-1), 4.95 (d, J = 1.6 Hz, 1 H, H-1′), 4.30 (t, J = 2.8 Hz, 1 H, H-2), 4.26 (dd, J = 12.3, 4.2 Hz, 1 H, H-6′a), 4.20-4.15 (m, 1 H, H-5′), 4.09 (dd, J = 12.3, 2.4 Hz, 1 H, H-6′b), 2.36-2.27 (m, 4 H, H-2′′ and H-2′′′), 2.14 (s, 3 H), 2.09 (s, 3 H), 2.07 (s, 3 H), 2.03 (s, 3 H), 2.02 (s, 3 H), 2.01 (s, 3 H), 2.00 (s, 3 H), 1.65-1.56 (m, 4 H, H-3′′ and H-3′′′), 1.33-1.22 (m, 56 H, 28 × CH2-lipid), 0.89-0.83 (m, 6 H, H-18′′ and H-18′′′); ¹³C NMR (101 MHz, CDCl3): δ = 173.4, 172.5, 169.84, 169.78, 169.76, 169.6, 169.5, 169.4, 169.3, 99.5, 76.4, 70.6, 70.4, 69.6 (3 × C), 69.5, 69.3, 68.7, 65.2, 61.7, 34.1, 34.0, 31.9, 29.7, 29.7, 29.6, 29.5, 29.5, 29.4, 29.3, 29.3, 29.2, 29.1, 24.9, 24.7, 22.7, 20.8, 20.7, 20.7, 20.6 (2 × C), 20.5, 20.5, 14.1; LRMS (ES+): m/z (%) = 1191.7 (100) [M + Na]+; HRMS (ES+): m/z [M + Na]+ calcd for C62H104O20Na: 1191.7019; found: 1191.7043.

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Data for β-peracetate 15: Oil; R f = 0.67 (PE-EtOAc, 6:4); [α]D ²0 -20.0 (c 0.73, CHCl3); IR (neat): 2923.1, 2853.6, 1753.3, 1369.4, 1225.5, 1043.8 cm; ¹H NMR (400 MHz, CDCl3): δ = 5.58 (dd, J = 3.2, 0.8 Hz, 1 H, H-2′), 5.41 (t, J = 10.4 Hz, 1 H, H-4), 5.39 (t, J = 10.0 Hz, 1 H, H-6), 5.23 (t, J = 10.0 Hz, 1 H, H-4′), 5.11 (t, J = 9.6 Hz, 1 H, H-5), 5.10-5.05 (m, 2 H, H-3 and H-3′), 4.70 (dd, J = 10.4, 2.4 Hz, 1 H, H-1), 4.67 (d, J = 0.8 Hz, 1 H, H-1′), 4.51 (t, J = 2.8 Hz, 1 H, H-2), 4.23 (dd, J = 12.4, 6.0 Hz, 1 H, H-6′a), 4.05 (dd, J = 12.4, 2.4 Hz, 1 H, H-6′b), 3.57 (ddd, J = 10.0, 6.4, 1.6 Hz, 1 H, H-5′), 2.40-2.30 (m, 2 H, H-2′′), 2.29-2.23 (m, 2 H, H-2′′′), 2.27 (s, 3 H), 2.09 (s, 3 H), 2.03 (s, 3 H), 2.01 (s, 3 H), 2.00 (s, 3 H), 2.00 (s, 3 H), 1.97 (s, 3 H), 1.63-1.54 (m, 4 H, H-3′′ and H-3′′′), 1.33-1.22 (m, 56 H), 0.88 (t, J = 6.8 Hz, 6 H, H-18′′ and H-18′′′); ¹³C NMR (101 MHz, CDCl3): δ = 173.4, 172.5, 169.84, 169.78, 169.76, 169.6, 169.5, 169.4, 169.3, 99.5, 76.4, 70.6, 70.4, 69.6 (3 × C), 69.5, 69.3, 68.7, 65.2, 61.7, 34.1, 34.0, 31.9, 29.7, 29.7, 29.6, 29.5, 29.5, 29.4, 29.3, 29.3, 29.2, 29.1, 24.9, 24.7, 22.7, 20.8, 20.7, 20.7, 20.6 (2 × C), 20.5, 20.5, 14.1; LRMS (ES+): m/z (%) = 1191.7 (100) [M + Na]+; HRMS (ES+): m/z [M + Na]+ calcd for C62H104O20Na: 1191.7019; found: 1191.7015.