Improved synthesis of substituted 2,6-dioxabicyclo[3.1.1]heptanes: 1,3-anhydro-2,4,6-tri-O-benzyl- and 1,3-anhydro-2,4,6-tri-O-p-bromobenzyl-β-d-mannopyranose
Improved synthesis of substituted 2,6-dioxabicyclo[3.1.1]heptanes: 1,3-anhydro-2,4,6-tri-O-benzyl- and 1,3-anhydro-2,4,6-tri-O-p-bromobenzyl-β-d-mannopyranose