反应详情

A solution of 1,6-anhydro-4-O-benzyl-3-deoxy-β-D-erythro-hexopyranos-2-ulose in benzyl alcohol was prepared as described in Example 6, except that 0.088 g of levoglucosenone were used as starting material and, 5 min after the addition of potassium benzoxide, a suspension of sodium borohydride (0.073 g) in ethanol (4 ml) was added to the mixture, which was then stirred for 0.5 h at room temperature, made neutral with acetic acid, evaporated under vacuum, and the resulting white residue transferred to a short column of silica, which was eluted with a gradient of ethyl acetate/hexane (from 1:2 to 2:1). The fractions found by t.l.c. to contain the title compound A were combined and evaporated, to give material that spontaneously crystallized (0.106 g, 64% from levoglucosenone). 1H-Nmr spectroscopy of this material showed it to be an 9:11 mixture of the title compound A and the D-arabino isomer determined from the relative intensities of their H-3 resonances.

1. custommaterial and, 5 min
2. additionwas added to the mixture, which
3. customevaporated under vacuum
4. washwas eluted with a gradient of ethyl acetate/hexane (from 1:2 to 2:1)
5. customevaporated
6. customto give material that
7. customspontaneously crystallized (0.106 g, 64% from levoglucosenone)
8. additionan 9:11 mixture of the title compound A