Dianhydro Sugars Not Involving the Anomeric Carbon Atom in Anhydro Bonds

Miscellaneous Dianhydro Sugars Not Involving the Anomeric Carbon Atom in Anhydro Bonds 

Most compounds of this type are derived from methyl hexosides methyl 2,6 3,4-dianhydro-a-D-altropyranoside309 398 400 516 and methyl 2,5 3,6-dianhydro-a- and /J-n-mannol iiranosides.517 From hexuloses, the synthetically useful l,5 3,6-dianhydro-D- 2raZ)i o-hex-2-ulose (172) has been prepared by regioselective monobenzylation of l,5 3,6-dianhydro-D-mannitol at C-4 (171a — 171b) followed by oxidation with tetrapropylammonium perruthenate.518 

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