Rhamnose, Fucose, and the Rhamnohexoses

The discovery of empirical rules of rotation of derivatives of the aldonic acids which indicated the configuration of the y-, and later the a-carbon atoms, made possible an advance in the solution of the problem of establishing the configurations of the synthetic higher-carbon sugars and the naturally-occurring rhamnose and fucose. The lactone rule was the earliest of these generalizations it was inferred from very extensive data. 

The first new result from the application of the lactone rule was the assignment of a complete configurational formula to natural rhamnose. The configuration of carbon atom 5 was indicated by the sign of rotation of the rhamnotetronic lactone, and therefore the Fischer formula could now be made complete it became 

Both the D-(o,o,o,o)- and D-(a,a,a,i8)-glucodeconic lactones of Philippe were strongly levorotatory (see p. 18) since their y-carbon atom is the carbon atom 2 of the antecedent o-a-glucooctose the levorotations indicated that the full configurations of this octose and its octitol are the following  

It then became probable that the o-a-glucooctitol, which Fischer had discovered, should be obtainable from the reduction of one of the unknown D-galaoctoses that should be expected from Fischer s D-/8-galaheptose, the configuration of which heptose had been established by Peirce 

Tollens-Elsner a Kurzes Handbuch der Kohlenhydrate J. A. Barth, Leipzig, 1935, p. 80. 

Improvements in the Details of the Fischer Cyanohydrin Synthesis op Higher-carbon Sugars and in the Identification of the Products 

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