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Synlett 2006(3): 0469-0471  
DOI: 10.1055/s-2006-926231
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of l-Vancosamine Derivatives from Methyl α-d-Mannopyranoside

Day-Shin Hsu, Takashi Matsumoto, Keisuke Suzuki*
Department of Chemistry, Tokyo Institute of Technology, and SORST-JST Agency, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8551, Japan
Fax: +81(3)57342788; e-Mail: ksuzuki@chem.titech.ac.jp;
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Publication History

Received 18 October 2005
Publication Date:
06 February 2006 (online)

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Abstract

Concise synthesis of l-vancosamine, the amino sugar constituent of vancomycin and other antibiotics, has been achieved. The key steps include (1) stereoselective addition of methylcerium reagent to oximino ether, and (2) stereoselective hydrogenation of 5,6-unsaturated glycoside with C(5) inversion to give l-vancos­amine derivative. C-Glycosidation of vancosaminyl acetate with ­iodoresorcinol proceeded in the presence of Sc(OTf)3 in high yield.

Key words

vancosamine - oximino ether - organocerium reagent - stereoselectivity - branched amino sugar - aryl C-glycoside

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Indeed, slightly lower yields were observed when less than five equivalents of the cerium reagent were used under the same conditions.

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Compound 15: mp 168-169 °C (CH2Cl2-hexane); [α]D 28 +10 (c 1.0, CHCl3). 1H NMR (400 MHz, CDCl3): δ = 8.16-8.13 (m, 2 H), 7.67-7.48 (m, 3 H), 6.99 (br s, 1 H), 5.96 (dd, J = 2.7, 10.3 Hz, 1 H), 5.07 (br s, 1 H), 4.17 (dq, J = 1.0, 6.6 Hz, 1 H), 2.61 (dd, J = 2.7, 12.6 Hz, 1 H), 2.15 (s, 3 H), 2.10 (dd, J = 10.3, 12.6 Hz, 1 H), 1.77 (s, 3 H), 1.29 (d, J = 6.6 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 169.1 (C), 167.7 (C), 156.3 (q, J = 37 Hz, C), 134.1 (CH), 130.0 (CH), 128.7 (CH), 128.3 (C), 115.2 (q, J = 290 Hz, C), 90.6 (CH), 73.4 (CH), 69.1 (CH), 57.2 (C), 35.3 (CH2), 21.2 (CH3), 21.0 (CH3), 17.2 (CH3). IR (neat): 3334, 3076, 2989, 1728, 1556, 1452, 1273, 1161, 1049, 908, 758, 715 cm-1. Anal. Calcd: C, 53.60; H, 5.00; N, 3.47. Found: C, 53.39; H, 5.25; N, 3.37.

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Compound 17: mp 89-90 °C (Et2O-hexane); [α]D 29 -0.3 (c 0.98, CHCl3). 1H NMR (400 MHz, CDCl3): δ = 8.38 (s, 1 H), 8.19-8.16 (m, 2 H), 7.68-7.28 (m, 8 H), 7.01 (d, J = 8.5 Hz, 1 H), 6.88 (br s, 1 H), 6.42 (d, J = 8.5 Hz, 1 H), 5.22 (br s, 1 H), 5.16 (s, 2 H), 4.89 (dd, J = 2.7, 12.2 Hz, 1 H), 4.20 (q, J = 6.6 Hz, 1 H), 2.49 (dd, J = 2.7, 12.4 Hz, 1 H), 2.28 (dd, J = 12.2, 12.4 Hz, 1 H), 1.84 (s, 3 H), 1.31 (d, J = 6.6 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 167.6 (C), 158.3 (C), 156.3 (q, J = 37 Hz, C), 155.3 (C), 136.5 (C), 134.1 (CH), 130.1 (CH), 128.9 (CH), 128.5 (CH), 128.2 (C), 127.8 (CH), 127.5 (CH), 126.9 (CH), 118.6 (C), 115.2 (q, J = 290 Hz, C), 104.2 (CH), 79.0 (C), 75.5 (CH), 73.7 (CH), 71.0 (CH), 70.9 (CH2), 56.7 (C), 37.1 (CH2), 20.4 (CH3), 17.8 (CH3). IR (neat): 3340, 3064, 2985, 1728, 1614, 1452, 1269, 1063, 908, 735, 714 cm-1. Anal. Calcd: C, 52.03; H, 4.07; N, 2.09. Found: C, 52.18; H, 4.33; N, 2.14.