Carbohydrates, exchange labeling

E. A. Cioffi, R. H. Bell, and B. Le, Microwave-assisted C-H bond activation using a commercial microwave oven for rapid deuterium exchange labeling (C-H -> C-D) in carbohydrates,... 

The choice of solvent can also be beneficial in another respect. This possibility was highlighted by the findings of Cioffi on the Raney Nickel catalyzed hydrogen-deuterium exchange of a model carbohydrate [l-0-methyl-/l-D-galactopyranoside] but under ultrasonic irradiation (Tab. 13.2) [43], Extensive deuteration at C-4 position occurred for a series of ethereal solvents, the C-3 position was deuterated by seven solvent systems and the C-2 position deuterated less extensively, also by seven solvent systems. For l,4-dioxane-D20 no labeling at the C-2 position occurred and for l,2-dimethoxyethane-D20 no C-3 labeling was observed. 

H. J. Koch and R. S. Stuart, A novel method for specific labelling of carbohydrates with deuterium by catalytic exchange, Carbohydr. Res., 59 (1977) C1-C6. 

Cioffi et al., who previously has studied the Raney Nickel catalyzed hydrogen-deuterium exchange of a model carbohydrate (l-O-methyl-yS-n-galactopyranoside) under ultrasonic irradiation, have extended their investigations into the microwave area [58]. Using a D20-tetrahydrofuran (THF) solvent mixture the above compound could rapidly (<10 min) be deuterated with 86% incorporation at one site and an even better incorporation (91%) for sucrose other sites were labeled less extensively. 

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