This method is based upon the R,S-configuration designation of each asymmetric carbon of a monosaccharide. According to the rule of configurational retention of each original asymmetric carbon, the Fischer projection of a monosaccharide can be converted into different views of the Haworth projection (the carbon-numbering orientation of the Haworth ring can be in either a clockwise or a counterclockwise direction, and the oxygen atom can be written at any corner of the ring). The d,l-configuration of a sugar in Haworth projection can be directly determined by designating the R,S-configuration of the highest-numbered asymmetric carbon; that is, the most distant carbon from the anomeric carbon. The R-configuration at this carbon corresponds to the d-family, and S- to the l-family. By comparing the stereochemistry of the anomeric carbon with that of the highest-numbered asymmetric carbon, the ,-anomer of a Haworth projection is directly notated. If these two carbons have the same configuration (R,R or S,S), the anomer is ; if different (R,S or S,R), the anomer is . This method proves to be general and widely applicable.
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Citation
Zhang, Qing-zhi; Zhang, Shen-song. J. Chem. Educ.1999, 76, 799.
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