Reagent Control of a Birch Reduction for the Synthesis of a 2‐Deoxyoligosaccharide Possessing a 1,4‐Dialkylhydroquinone

We have developed a versatile deprotection method for the synthesis of 2-deoxyoligosaccharides containing a 1,4-dialkylhydroquinone moiety at the anomeric position. The Birch reduction of a 2,6-dideoxy monosaccharide with potassium and 1,3-pentadiene gave the deprotected product without any undesired reduction. The utility of this method was then demonstrated in the Birch reduction of a landomycin E deoxytrisaccharide. Pd-catalysed hydrogenation led to the anomerization, or cleavage, of the glycosidic linkages. In contrast, Birch reduction based on the optimized conditions followed by treatment with mCPBA (m-chloroperoxybenzoic acid) provided the fully deprotected deoxytrisaccharide in 65 % overall yield. These results show that the Birch reduction is a powerful deprotection method for the synthesis of complex natural glycosides, including 2-deoxyoligosaccharides.