Glycals hydroxylation

Reactions of some furanoid glycals having free 3-hydroxyl (518 and 522) and 3-0-benzyl groups (520 and 524) with AcOF gave different products in the former and the latter groups of compounds, respectively, addition reaction occurred mainly from the same (to give 519 and 523, respectively) and from the opposite sides [to give 521 and 525 (with 526), respectively] of the substituents at C-3 (see Table V). 

Scheme 2.4 Polymer support silylene linking method for hindered hydroxyl-bearing glycals.

Other methods of introducing amino substituents at C-2 by glycal additions include the use of the (saltmen)Mn(N) complex and trifluoroacetic anhydride,51 and the photochemical addition of Ar-chloro-chloroacetamide.52 In both cases tri-O-acetyl-D-glucal gives 2-amino-2-deoxy-D-glucose adducts, in the former case with the hydroxyl group at C-l, and in the latter with chlorine which can be displaced by alkoxy at that position. 

Importantly, this glycosylation reaction can be promoted under nonacidic conditions and its scope is thereby widened. Glycals with allylic hydroxyl... 

Scheme 29 13DPRs of the enantiopure hydroxylated nitrones 97 and 100 with the glycals 98 and 101 [73]... 

The 2-hydroxyglycals (for example, I) are anhydrosugars derived from the cyclic form by loss of the hydroxyl group from Cl and the hydrogen atom from C2. They differ from the parent glycal (for example, II) by the... 

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