Protecting-group effect

A general trend in protecting group effects exists. For galactose, the most thoroughly explored series of donors, we find that the substituent plays a significant... 

Fiirstner et al. reported the same protecting-group effect using complex GN, with the free phenol 79 exclusively furnishing Z-80 (Scheme 2.31) [53]. They ruled out the interaction of the free phenol with the catalyst, and proved by semi-empirical calculations that there is no correlation between the E/Z ratios and the thermodynamic stabilities of the products, so this effect remains unexplained. The first-generation catalyst Gl is unable to react with the trisubstituted olefin at CIO. 

Kalikanda, J., and Li, Z. (2011). Study of the Stereoselectivity of 2-Azido-2-deoxygalactosyl Donors Remote Protecting Group Effects and Temperature Dependency. J. Org. Chem., 76(13), 5207-5218. 

Green LG, Ley SV (2000) Protecting groups effects on reactivity, glycosylation specificity and coupling efficiency. In Ernst B, Hart GW, Sinay P (eds) Carbohydrates in chemistry and biology, vol 1. Wiley-VCH, Weinheim, pp 427 48... 

Protecting Groups Effects on Reactivity, Glycosylation Stereoselectivity, and Coupling Efficiency... 

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