Synlett 2010(6): 893-896  
DOI: 10.1055/s-0029-1219539
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

A Facile H2SO4/4 Å Molecular Sieves Catalyzed Synthesis of 2,3-Unsaturated O-Glycosides via Ferrier-Type Rearrangement

Jiafen Zhoua, Bo Zhanga, Guofang Yanga, Xuan Chena, Qingbing Wanga, Zhongfu Wangb, Jianbo Zhang*a, Jie Tanga
a Department of Chemistry, East China Normal University, Shanghai 200062, P. R. of China
e-Mail: jbzhang@chem.ecnu.edu.cn;
b School of Life Sciences, Northwest University, Xi’an 710069, P. R. of China
Further Information

Publication History

Received 13 November 2009
Publication Date:
18 February 2010 (online)

Abstract

A novel method for synthesizing 2,3-unsaturated glycosides has been developed using a metal-free catalytic system. This catalyst, sulfuric acid/4 Å molecular sieves can catalyze the reaction of 3,4,6-tri-O-acetyl-d-glucals and a wide range of alcohols at room temperature, affording 2,3-unsaturated glycosides in good α-selectivity (α/β > 6:1) via a Ferrier-type rearrangement.

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General Experimental Procedure
Typically, H2SO4 (0.3 equiv, 16 mL) was added to the mixture of d-glucal (1 mmol, 272 mg), 4 Å MS (272 mg) and alcohol (1.5 equiv) in CH2Cl2, and the reaction mixture was stirred for 5 min at r.t. After the reaction was completed, the reaction mixture was filtered and washed with CH2Cl2. The combined organic layer was washed with sat. NaHCO3 solution (10 mL) and sat. brine (10 mL), and then dried over anhyd Na2SO4. After evaporation of the solvent under reduced pressure, the crude products were purified by silica gel column chromatography (PE-EtOAc = 10:1).

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Selected Spectral Data
n -Pentyl 4,6-Di- O -acetyl-2,3-dideoxy-a- d - erythro -hex-2-enopyranoside (5b)
¹H NMR (500 MHz, CDCl3): d = 0.91 (t, J = 6.7 Hz, 3 H), 1.34-1.37 (m, 4 H), 1.59-1.63 (m, 2 H), 2.07-2.10 (m, 6 H), 3.48-3.53 (m, 1 H), 3.75-3.80 (m, 1 H), 4.09-4.27 (m, 3 H, H-5, H-6a, H-6b), 5.03 (s, 1 H, H-1), 5.30-5.32 (dd, 1 H, J = 9.6 Hz, H-4), 5.83-5.89 (m, 2 H, H-2, H-3) ppm. ¹³C NMR (125 MHz, CDCl3): d = 13.94, 20.69, 20.88, 22.40, 28.31, 29.32, 62.99, 65.27, 66.81, 68.87, 94.31, 127.92, 128.89, 170.22, 170.71 ppm. ESI-MS: m/z = 323.10 [M + Na+].
n -Decyl 4,6-Di- O -acetyl-2,3-dideoxy-a- d - erythro -hex-2-enopyranoside (6b)
¹H NMR (500 MHz, CDCl3): d = 0.86 (t, 3 H), 1.26-1.35 (m, 16 H), 2.07-2.09 (m, J = 9.2 Hz, 6 H), 3.49 (m, 1 H), 4.09-4.26 (m, 3 H, H-5, H-6a, H-6b), 5.01 (s, 1 H, H-1), 5.29-5.32 (dd, J = 1.3, 9.7 Hz, 1 H, H-4), 5.83-5.88 (m, 2 H, H-2, H-3) ppm. ¹³C NMR (125 MHz, CDCl3): d = 14.00, 20.69, 20.87, 22.58, 25.67, 26.16, 29.23, 29.36, 29.47, 31.81, 32.70, 62.92, 64.37, 66.80, 68.94, 94.32, 127.90, 128.88, 170.27, 170.76 ppm. ESI-MS: m/z = 393.20 [M + Na+].
2-Ethylhexyl 4,6-Di- O -acetyl-2,3-dideoxy-a- d - erythro -hex-2-enopyranoside (12b)
¹H NMR (500 MHz, CDCl3): d = 0.86-0.91 (m, 6 H), 1.26-1.33 (m, 8 H), 1.34-1.42 (m, 1 H), 2.09-2.10 (m, J = 5.7 Hz, 6 H), 3.36-3.38 (q, 1 H), 3.54-3.55 (d, 1 H), 3.70-3.71 (t, 1 H), 4.08-4.25 (m, 3 H, H-5, H-6a, H-6b), 5.00 (s, 1 H, H-1), 5.29-5.31 (dd, J = 9.7 Hz, 1 H, H-4), 5.82-5.94 (m, 2 H, H-2, H-3) ppm. ¹³C NMR (125 MHz, CDCl3): d = 11.02, 13.99, 20.67, 20.87, 22.94, 23.68, 28.93, 30.49, 39.57, 63.03, 65.28, 66.87, 72.64, 94.45-94.53, 127.95, 128.74, 170.21, 170.71 ppm. ESI-MS: m/z = 365.14 [M + Na+].
2-Cyanoethyl 4,6-Di- O -acetyl-2,3-dideoxy-a- d - erythro -hex-2-enopyranoside (15b)
¹H NMR (500 MHz, CDCl3): d = 2.08-2.10 (m, J = 10.0 Hz, 6 H), 2.64-2.71 (m, 2 H), 3.76-3.97 (m, 2 H), 4.12-4.22 (m, 3 H, H-5, H-6a, H-6b), 5.07 (s, 1 H, H-1), 5.29-5.31 (dd, 1 H, J = 1.0, 9.5 Hz, H-4), 5.81-5.93 (m, 2 H, H-2, H-3) ppm. ¹³C NMR (125 MHz, CDCl3): d = 18.96, 20.56, 20.72, 62.69, 63.26, 64.85, 67.14, 94.60, 117.58, 126.70, 129.57, 170.13, 170.59 ppm. ESI-MS: m/z = 306.07 [M + Na+].
Trichloroethyl 4,6-Di- O -acetyl-2,3-dideoxy-a- d - erythro -hex-2-enopyranoside (17b)
¹H NMR (500 MHz, CDCl3): d = 2.07-2.13 (m, J = 10.8 Hz, 6 H), 4.17-4.18 (d, 2 H), 4.27-4.36 (m, 3 H, H-5, H-6a, H-6b), 5.31 (s, 1 H, H-1), 5.37-5.38 (dd, J = 9.2 Hz, 1 H, H-4), 5.97-6.00 (m, 2 H, H-2, H-3) ppm. ¹³C NMR (125 MHz, CDCl3): d = 20.76, 20.87, 62.66, 65.01, 67.49, 76.15, 79.61, 96.37, 126.38, 130.20, 170.39, 170.92 ppm. ESI-MS: m/z = 382.94 [M + Na+].