Methyl hexopyranoside with -manno

Benzyl 2,4-diamino-2,3,4,6-tetradeoxy-cx and jS-ara6mo-hexopyranoside have been prepared by direct azide displacement reactions on the corresponding benzyl 3,6-dideoxy-2,4-di-0-methanesulphonyl a and jS- -j/o-hexopyrano-sides. A new synthesis of the tobrosamine derivative (24) from methyl a-D-manno-pyranoside is outlined in Scheme 12. Direct reaction of (25) with... 

The experimental results were in full agreement with the above predictions. The sodium borohydride reductimi in methanol of methyl 4, 6-0-benzylidene-3-C>-methyl-p-D-arabino-hexopyranosid-2-ulose 33 gave a crude reduction product that consisted almost exclusively of methyl 4, 6-0-benzylidene-3-0-methyl-a-D-mannopyranoside 35 (Fig. 1.8) (the manno to gluco ratio was 19 1). The sodium borohydride reduction of methyl 4,6-0-benzylidene-3-t)-methyl-a-D-arab//i >-hexopyranosid-2-ulose 34 in methanol afforded methyl 4, 6-0-benzylidene-3-(9-methyl-p-D-glucopyranoside 36 as the only product. 

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