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A New Formula for the Description of the Conformation of Pyranoid Sugars
Author(s) -
Szejtli J.
Publication year - 1971
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19710230303
Subject(s) - ring (chemistry) , substituent , chemistry , stereochemistry , cyclohexane conformation , crystallography , molecule , hydrogen bond , organic chemistry
Reeves' conformational formulas of aldopyranoses can be described by combinations of letters and numbers. This system may be especially useful when many conformational formulas would have to be printed. The C1 conformation of sugars in the D ‐series is to be visualized with the C 1 atom on the right, below, and the C 4 atom on the left, above in the chair form = 4 C 1 , and the ring members must be numbered clockwise. Applying these conventions, both in the D ‐ and L ‐series the axial substituents attached to the C 1 , C 3 and C 5 atoms in the C1 conformation are directed downwards, while those affixed to the C 2 and C 4 atoms point upwards relative to the plane of the ring. The C 5 ‐substituent in pyranoses of C1 conformation is axial in the case of L ‐sugars, and equatorial in D ‐sugars. The axial position is designated in the formula by its location written in parentheses and the substituents other than ‐H and ‐OH are indicated behind the parentheses. 4 C 1 means an aldopyranose ring of C1 conformation. 4 C 1 (‐)5‐CH 2 OH means β‐ D ‐glucopyranose, 4 C 1 (1,2)5‐CH 2 OH denotes α‐ D ‐mannopyranose. If the figure “5” also occurs in parentheses, the symbol represents an L ‐sugar, e.g., 4 C 1 (1,2,5)5‐CH 2 OH means β‐ L ‐gulose, or 4 C 1 (1,2,5)5‐COOH,3‐deoxy is 3‐deoxy‐β‐ L ‐guluronic acid in C1 conformation. The 1C conformation is designated as 1 C 4 , B1 as 4 B 1 , B2 as 5 B 2 , etc. The ring members are numbered in the “alternative” conformations (1C, 1B, 2B, 3B) counter‐clockwise.