Synlett 2005(17): 2685-2687  
DOI: 10.1055/s-2005-917071
LETTER
© Georg Thieme Verlag Stuttgart · New York

Stereoselective Synthesis of 1,2-13 C 2-l-Fucose, 1,2-13 C 2-Fucono-γ-lactone and 1,2-13 C 2-Fucono-γ-lactol from Non-Sugar Starting Material

John M. Gardiner*a, Nitesh R. Panchala, William T. Stimpsona, John M. Herbertb, George J. Ellamesb
a School of Chemistry, The University of Manchester, Faraday Building, Sackville Street, Manchester M60 1QD, UK
Fax: +44(870)1692995; e-Mail: gardiner@manchester.ac.uk;
b sanofi-aventis Research, Alnwick Research Centre, Willowburn Avenue, Alnwick, Northumberland NE66 2JH, UK
Further Information

Publication History

Received 12 May 2005
Publication Date:
05 October 2005 (online)

Abstract

An efficient synthesis is reported for the preparation of l-fucose, and of l-fucofuranose, from 1. The route is designed to ­facilitate 13C labelling at C1 and/or C2, and the synthesis of 1,2-13 C 2-fucose as its tetraacetate is described. The C2 and C3 stereocentres are introduced using asymmetric dihydroxylation, and the lactone ring size resulting from cyclisation of 4 was controlled to provide the l-fucofuranone 5, whose structure was unambiguously established by X-ray crystal analysis of the derived trisilyl ether 6. Generation of the fucose lactol 7 by reduction of 6 followed by deprotection then provided l-fucose, isolated as its peracetate 8.

7

Typical Experimental for Synthesis of 5.
To a solution of 4 (2.169 g, 8.66 mmol) in MeOH (146.5 mL) and H2O (19 mL) was added p-TSA (165 mg, 0.866 mmol) and the reaction mixture was stirred at 60 °C until no starting material was visible by TLC. The solvent were removed and chromatography afforded 5 as a white solid (1.172 g, 7.10 mmol, 82%). 1H NMR (300 MHz, MeOD): δ = 4.34 [1 H, ddd, J = 142.8, 8.7, 4.9 Hz, 13CO13CH(OH)], 4.22-4.15 [1 H, m, 13CO13CH(OH)CH(OH)], 3.95-3.87 [1 H, m, CH(OH)CH(OH)CH3], 3.95-3.87 (1 H, m, CHCH3), 1.32 (3 H, d, J = 6.4 Hz, OCHCH 3). 13C NMR (75.5 MHz, MeOD): δ = 177.5, 176.8 [d, J = 55.9 Hz, 13 CO13CH(OH)], 77.2, 76.4 (d, J = 55.9 Hz, 13CO13 CH(OH)]. HRMS (+ES): m/z calcd for C4 13C2H10O5: 182.0939. Found: 182.0936 [M + NH4]+. Mp 91-95 °C. [α]D 22 +60.8 (c 0.5, H2O).

11

Typical Experimental for Synthesis of 7:
DIBAL (0.52 mL, 0.52 mmol) was added dropwise to a solution of 6 (86.6 mg, 0.17 mmol) in CH2Cl2 (3 mL) at
-78 °C. After 1 h the reaction was quenched with MeOH and the solvent was removed. The colourless oil was purified by chromatography to give 7 as white crystals (84 mg, 0.17 mmol, 97%). 1H NMR (300 MHz, CDCl3): β-anomer, δ = 5.16 (1 H, ddt, 1 J 13 CH = 171.8 Hz, 3 J 13 C H O H = 12.1 Hz and 3 J 13 CH 13 CH = 4.1 Hz), 4.11-4.07 (1 H, m), 4.00-3.80 (2 H, m), 3.82 (1 H, ddd, J = 12.1, 4.9, 1.5 Hz), 3.68-3.63 (1 H, m), 1.21 (3 H, d, J = 6.4 Hz); α-anomer, δ = 5.06 (1 H, dd, 1 J 13 CH = 174.8 Hz, 3 J 13 C H O H = 12.1 Hz), 4.00-3.82 (4 H, m), 3.56 (1 H, ddd, J = 12.1, 4.9, 2.3 Hz), 1.12 (3 H, d, J = 6.0 Hz). Both anomers, δ = 0.92-0.88 (54 H, m). 13C NMR (75.5 MHz, CDCl3): β-anomer, δ = 97.9 (d, 1 J 13 CH 13 CH = 41.4 Hz), 80.8 (d, 1 J 13 CH 13 CH = 41.4 Hz). α-anomer, δ = 104.0 (d, 1 J 13 CH 13 CH = 44.3 Hz), 81.8 (d, 1 J 13 CH 13 CH = 44.3 Hz). HRMS (+ES): m/z calcd for C22 13C2H54O5Si3: 531.33245. Found: 531.3243 [M + Na]+. These assignments are consistent with data for a number of related furanose and furanoside structures where the 1,2-trans isomer shows the more downfield 13C shift for C1 and the smaller J 1,2. [12] The nomenclature is consistent with IUPAC conventions for C6 furanosides. [13] This reaction has also been carried out on multi-gram scale.

15

The crystal structures both showed four independent molecules in the unit cell, each differing in conformations about C-O bonds, with little evidence of intramolecular H-bonding. These structures are also noteworthy as there are few X-ray structures of 13C2-labelled compounds.

16

Typical Experimental for Synthesis of 8.
To a solution of 7 (150 mg, 0.295 mmol) in dioxane-H2O was added concd HCl. The mixture was stirred overnight. Filtration through Amberlite and removal of the solvents afforded the crude sugar. Then, Ac2O (10 equiv, 2.95 mmol, 0.278 mL), pyridine (12 equiv, 3.54 mmol, 0.286 mL) and CH2Cl2 (5 mL) were added and the mixture stirred for 14 h. The reaction was quenched by the addition of H2O and washed with CuSO4 solution. Purification by chromatography yielded 8 as white crystals (94.7 mg, 0.28 mmol, 96%). 1H NMR (400 MHz, CDCl3): β-anomer, δ = 5.68 (1 H, dd, J = 174.5, 7.9 Hz, H1), 5.60 (1 H, dd, J = 113.4, 10.2, 7.9 Hz), 5.33-5.27 (1 H, m), 5.13-5.08 (1 H, m), 3.99-3.94 (1 H, dd, J = 12.1, 6.4, 6.0 Hz), 2.20, 2.13, 2.05, 2.01 (3 H, s), 1.24 (3 H, d, J = 6.4 Hz, H6); α-anomer, δ = 6.65 (1 H, dd, J = 177.8, 3.4 Hz, H1), 5.35 (2 H, m), 5.08 (1 H, ddd, J = 153.7, 9.8, 3.4 Hz, H2), 4.28 (1 H, dd, J = 12.8, 6.5 Hz), 1.12 (3 H, d, J = 6.4 Hz, H6). 13C NMR (75.5 MHz, CDCl3): β-anomer, δ = 92.6 (d, J = 47.4 Hz), 68.3 (d, J = 47.4 Hz). α-anomer, δ = 90.50 (d, J = 48.3 Hz), 66.85 (d, J = 48.3 Hz). HRMS (EI): m/z calcd for C12 13C2H20O9: 357.1069. Found: 357.1067 [M + Na]+. α-Anomer: [α]D 22 - 48 (c 1, CHCl3); β-anomer: [α]D 22 -113 (c 1, CHCl3).