[C:1]1(=[O:7])[CH2:6][CH2:5][CH2:4][CH2:3][CH2:2]1.O=[CH:9][C@H:10]([C@H:12]([C@@H:14]([C@@H:16]([CH2:18][OH:19])[OH:17])[OH:15])[OH:13])[OH:11].I>ClCCl>[CH2:4]1[CH2:5][CH2:6][C:1]2([O:11][C@@H:10]([C@H:12]3[O:13][C@@H:18]4[O:19][C:1]5([CH2:6][CH2:5][CH2:4][CH2:3][CH2:2]5)[O:17][C@H:16]4[C@H:14]3[OH:15])[CH2:9][O:7]2)[CH2:2][CH2:3]1To a mixture of 150 ml of cyclohexanone and 120 ml of dichloromethane were added 10.0 g of D-mannose and 175 mg of hydriodic acid (57%) and the mixture was refluxed with stirring in a water bath at 65° C. for 8 hours. During this reaction, the refluxing solvent was dried with 20 g of Molecular Sieves 3A interposed between the reaction vessel and the cooling jacket. The reaction mixture was diluted with benzene, washed with aqueous sodium bicarbonate and water and dried over anhydrous magnesium sulfate. The solvent and cyclohexanone were distilled off under reduced pressure to give 11.9 g (82.6%) of 2,3:5,6-di-O-cyclohexylidene-α-D-mannofuranose. After recrystallization from cyclohexane, it melted at 122°-124° C.
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