Can α-D-fructose and β-D-fructose be classified as anomers?

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11ecba2d_12bc_a4a5_a3bf_35b5719bd424_MD0008_00 Stereoisomers are molecules that have the same atom connectivity but differ in the spatial orientation of the atoms. Stereoisomers contain one or more stereocenters, or chiral centers, which consist of an atom (typically carbon) with four different substituents. Diastereomers, a type of stereoisomer, have more than one stereocenter and differ in orientation at some, but not all, stereocenters. Some sugars can be classified as a special kind of diastereomer, known as an anomer, that differs in configuration at only the anomeric carbon. The α and β designations in a sugar's name refer to different orientations of the hydroxyl group at the anomeric carbon. Carbon atoms in sugars are numbered beginning with the carbon that is closest to the anomeric carbon when the sugar is in linear form. For aldoses such as glucose, the anomeric carbon is C1, whereas for ketoses such as fructose, the anomeric carbon is C2. α-D-fructose and β-D-fructose are diastereomers that differ in orientation at C2 (the anomeric carbon) only. Therefore, α-D-fructose and β-D-fructose are anomers. (Choice B) Anomers differ in configuration at only one position (the anomeric carbon), not multiple positions. (Choice C) Epimers are diastereomers that differ in configuration at one position, and anomers are a specific type of epimer that differs at the anomeric carbon. However, for fructose, the anomeric carbon is C2, not C1. (Choice D) α-D-fructose and β-D-fructose are not enantiomers because they differ in configuration at only one stereocenter, whereas enantiomers differ in configuration at every stereocenter. The enantiomer of α-D-fructose is α-L-fructose, and the enantiomer of β-D-fructose is β-L-fructose. Educational objective: Stereoisomers are molecules containing the same atom connectivity but different spatial orientation of the atoms. Sugar stereoisomers that differ in orientation at only one stereocenter are known as epimers, a specific kind of diastereomer. If the sugars differ in configuration at only the anomeric carbon (denoted by α and β in the sugar's name), they are classified as anomers, a special kind of epimer.

Can α-D-Fructose and β-D-Fructose Be Classified as Anomers