Through Protection of Diols with Acetals or Ketals

2 Through Protection of Diols with Acetals or Ketals 

SCHEME 2.19 Notable formations of acetals and ketals on pyranosides. 

With orientations similar to those in glucopyranosides, the remaining hydroxyls of 4,6-O-protected galactopyranosides are difficult to selectively protect. Taking 

SCHEME 2.23 TMSOTf- or Cu(OTf)2-catalyzed Et3SiH-reductive 3-O-benzylation of 

SCHEME 2.24 Dependence of the regioselective acylation of 4,6-0-benzylidene-D-galac-topyranosides with (a) solvent and (b) anomeric configuration. 

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