Kinetic isotope effect , glycosylation

Initially, it was thought that the glycosylation proceeded through the episulfonium intermediate 35. However, the measured kinetic isotope effect (KIE) of 1.17-1.20 suggests an oxocarbenium ion intermediate rather than an episulfonium ion [27], Furthermore, computational studies also indicated that the 3E oxocarbenium ion 36 is considerably more stable than the strained episulfonium ion 35. The observed stereoselectivity was explained by an inside attack on the 3E oxocarbenium ion. 

HEAVY ATOM AND REMOTE HYDROGEN KINETIC ISOTOPE EFFECTS IN GLYCOSYL TRANSFER... 

Table 3.3 sets out kinetic isotope effects for a series of hydrolyses of glycosyl derivatives. A number of features emerge ... 

Table 3.3 Kinetic isotope effects for hydrolysis of various glycosyl derivatives. The isotopic quasi-racemate method was used for all measurements except those for AMP, where the remote label method was used.

Table 5.3 a-Deuterium kinetic isotope effects on the hydrolysis of the glycosyl-enzyme intermediates of retaining glcyosidases. 

Keywords Acetal, Anomeric effect, Diastereoselectivity, Glycosylation, Ion pair. Kinetic isotope effect, Stereoelectronic effects... 

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