First Stereoselective Total Synthesis of Ophiocerins B and C

J. S. Yadav; P. Naga Lakshmi; S. J. Harshavardhan; B. V. Subba Reddy

doi:10.1055/s-2007-982579

LETTER

First Stereoselective Total Synthesis of Ophiocerins B and C

J. S. Yadav*, P. Naga Lakshmi, S. J. Harshavardhan, B. V. Subba Reddy
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500007, India
Fax: +91(40)27160512; e-Mail: yadavpub@iict.res.in;

Abstract

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Abstract

An elegant synthesis of ophiocerins B and C is accomplished for the first time with 3R,4R,6R and 3S,4S,6R-configuration. Of these three stereogenic centers, the C-3/C-4 vic-diol was created by Sharpless asymmetric dihydroxylation, while the C-6 stereocenter was achieved from known chiral epoxide. The synthesis of ophiocerins B and C defined the absolute stereochemistry of these natural products.

Key words

Sharpless asymmetric dihydroxylation - ophiocerin - tetrahydropyran derivative

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Referenzen

References and Notes

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Spectroscopic Data for Target Molecules
Ophiocerin B (2): pale yellow oil; [α]_D ²⁵ -34.0 (c 0.25, CH₂Cl₂). IR (neat): ν_max = 3388, 1452, 1380, 1266, 1079, 1004 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 3.99 (br s, 1 H), 3.97 (dd, 1 H, J = 1.6, 12.4 Hz), 3.85 (ddq, 1 H, J = 2.6, 6.3, 12.0 Hz), 3.73 (dd, 1 H, J = 2.3, 12.2 Hz), 3.47 (br s, 1 H,), 2.21 (d, 1 H, J = 8.0 Hz), 1.81 (ddd, 1 H, J = 3.1, 11.3, 14.3 Hz), 1.64-1.59 (m, 2 H) 1.18 (d, 3 H, J = 6.0 Hz). ¹³C NMR (75 MHz, CDCl₃): δ = 68.4, 68.2, 67.4, 67.2, 36.0, 21.1. ESI-MS: m/z = 155 [M + Na]⁺. HRMS: m/z calcd for C₆H₁₂O₃Na: 155.0684 [M⁺ + Na]; found: 155.0691.
Ophiocerin C (3): white solid, mp 80-82 °C; [α]_D ²⁵ +42.2 (c 0.1, CH₂Cl₂). IR (neat): ν_max = 3413, 1460, 1380, 1262, 1136, 1080, 1006 cm^-1. ¹H NMR (500 MHz, CDCl₃): δ = 3.98 (dd, 1 H, J = 5.3, 11.4 Hz), 3.61-3.47 (m, 3 H), 3.16 (dd, 1 H, J = 9.8, 11.3 Hz), 2.10-2.05 (br s, 1 H), 2.02-1.97 (m, 2 H), 1.37 (ddd, 1 H, J = 11.3, 11.3, 12.8 Hz), 1.20 (d, 3 H, J = 6.4 Hz). ¹³C NMR (75 MHz, CDCl₃): δ = 73.4, 72.6, 72.4, 69.6, 40.5, 21.2. ESI-MS: m/z = 155 [M + Na]⁺. HRMS: m/z calcd for C₆H₁₂O₃Na: 155.0684 [M⁺ + Na]; found: 155.0691.