Conformational energy acyclic model compounds

From the methodological point of view, a different F factor derived from the correlation of energies of relevant acyclic compounds should have been used. The anomeric carbon atom in II is secondary, whereas in 2-substituted tetrahydropyrans it is tertiary. The introduction of a third substituent at the anomeric carbon may result in a change of preferred conformation (58, 59), appropriate angles (60), and the magnitude of the anomeric effect (61), thus making cyclic models inadequate for the calculation presented above. 

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