Anomeric Effect and Related Stereoelectronic Effects

There are several good books and review articles published on this subject [1-6]. 

In the case of o-glucose and o-galactose, the anomer with the equatorial Cl hydroxyl group (P) is, as expected, more stable, whereas in the case of o-maimose, the anomer with the axial Cl hydroxyl group (a) is more stable. The o-maimose is a special case and it will be discussed later. 

The preference for the axial orientation of the Cl substituent in o-glucopyranose was found to increase with increasing electronegativity of the Cl substituent (Table 2.3). 

The first rationalization of the tendency of aglycons of alkyl glycopyranosides to assume axial orientation was proposed by Edward [12] and most probably was inspired by the Corey study on the stereochemistry of some a-halocyclohexanones [13], in which it was determined that the most stable conformation of a-chloro-and a-bromocyclohexanone is the chair form, in which the halogen substituent is axial (2 in Fig. 2.1). 

Miljkovic, Electrostatic and Stereoelectronic Effects in Carbohydrate Chemistry, 

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A. J. Kirby, The Anomeric Effect and Related Stereoelectronic Effects at Oxygen, Springer-Verlag, New %rk, 1983. 

A. J. Kirby, The Anomeric Effect and Related Stereoelectronic Effects at Oxygen (Berlin, Springer, 1983) G. R. J. Thatcher (ed.), The Anomeric Effect and Associated Stereoelectronic Effects (Washington, American Chemical Society, 1993) and E. Juaristi and G. Guevas, The Anomeric Effect (Boca Raton, FL, CRC Press, 1994). 

Kirby AJ. The anomeric effect and related stereoelectronic effects at oxygen. New York Springer 1983. 

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