Peracetylated 1,6-dibromo-d-glucitol as efficient precursor of 1,6-diiodo and some mono-, disubstituted and heterocyclic d-glucitol derivatives

2,3,4,5-Tetra- O -acetyl-1,6-dibromo-1,6-dideoxy- d -glucitol ( 1a ) obtained from d -glucitol was easily transformed into the 1,6-diiodo derivative in excellent yield (97%) by reaction with an excess of sodium iodide in refluxing butanone in 2 h. When the reaction time was prolonged to 24 h and the crude product was acetylated, 1,2,3,4,5-penta- O -acetyl-6-deoxy-6-iodo- d -glucitol and d -glucitol hexaacetate were isolated in 50 and 26% yields, respectively. The monodehalogenation then took place regioselectively at C-1. This regioselectivity allowed the synthesis of some mono- and disubstituted derivatives of d -glucitol. Thus, the peracetylated derivatives of d -glucitol, 6-bromo, 6-bromo-1- S -butyl, 6-bromo-1- S -octyl, 6- S -butyl, 6- S -butyl-1- S -octyl, 1- S -butyl, 1,6-di- S -octyl and 6- S -phenyl were synthesised in good to excellent yields. With S  as binucleophilic reagent, 1a gave mainly the thiepane derivative (75%) plus the 1- S -acetyl-2,6-anhydro- d -glucitol derivative as a by-product (10%).