Synthesis of α-D-GalpN₃-(1-3)-D-GalpN₃: α- and 3-O-selectivity using 3,4-diol acceptors

Emil Glibstrup and
Christian Marcus Pedersen

Full Research Paper
Published 08 Nov 2018

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1. Graphical Abstract
2. Scheme 1: Undesired migration followed by benzylation of the 3-O-Bz GalN₃ using several different benzylation...
  
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3. Scheme 2: Simple synthesis of two acceptors and two donors from the same common and readily available buildin...
  
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4. Scheme 3: Challenging the α,3-O-selectivity with the different 6-O-protecting group variants.
  
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5. Scheme 4: Representative glycosylations with closely related systems [34,44].
  
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6. Scheme 5: Capping the free 4-OH, allowing for easier separation of mixtures obtained during glycosylation.
  
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7. Scheme 6: Pseudotrisaccharide synthesis for LTA elucidation.
  
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Beilstein J. Org. Chem. 2018, 14, 2805–2811, doi:10.3762/bjoc.14.258

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Silyl-protective groups influencing the reactivity and selectivity in glycosylations

Mikael Bols and
Christian Marcus Pedersen

Review
Published 16 Jan 2017

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1. Graphical Abstract
2. Figure 1: Silicon-protective groups typically used in carbohydrate chemistry.
  
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3. Scheme 1: Glycosylation with sulfoxide 1.
  
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4. Scheme 2: Glycosylation with imidate 4.
  
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5. Scheme 3: Glycosylation with thioglycoside 7.
  
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6. Scheme 4: In situ formation of a silylated lactosyl iodide for the synthesis of α-lactosylceramide.
  
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7. Figure 2: Comparison of the reactivity of glycosyl donors with the pK_a of the corresponding piperidinium ions....
  
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8. Figure 3: Conformational change induced by bulky vicinal protective groups such as TBS, TIPS and TBDPS. The v...
  
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9. Scheme 5: An example of a “one pot one addition” glycosylation, where 3 glucosyl donors are mixed with 2.1 eq...
  
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10. Scheme 6: Superarmed-armed glycosylation with thioglycoside 34.
  
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11. Scheme 7: One-pot double glycosylation with the conformationally armed thioglycoside 37.
  
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12. Scheme 8: Superarmed-armed glycosylation with thioglycoside 41.
  
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13. Figure 4: Donors disarmed by the di-tert-butylsilylene protective group.
  
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14. Figure 5: The influence of a 3,6-O-tethering on anomeric reactivity and glycosylation selectivity. The α-thio...
  
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15. Scheme 9: Regio- and stereoselective glycosylation using the superarmed thioglycoside donor 20.
  
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16. Scheme 10: Superarmed donors used for C-arylation and the dependence of the size of the silylethers on the ste...
  
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17. Scheme 11: β-Selective glucosylation with TIPS-protected glucosyl donors. The α-face is shielded by the bulky ...
  
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18. Scheme 12: β-Selective rhamnosylation with a conformationally inverted donor.
  
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19. Scheme 13: α-Selective galactosylation with DTBS-protected galactosyl donors.
  
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20. Scheme 14: β-Selective arabinofuranosylation with a DTBS-protected donor.
  
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21. Scheme 15: α-Selective glycosylation with a TIPDS-protected glucal donor.
  
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22. Scheme 16: Highly β-selective glucuronylation using a 2,4-DTBS-tethered donor.
  
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