Sugars neighboring-group reactions

The obituary article by Goodman (Kingston, R. I.) describes the career of the late B. R. Baker, emphasizing especially Baker s contribution of useful synthetic procedures in the sugar field by application of neighboring-group reactions for configurational inversion. 

B. R. Baker and T. L. Hullar, Synthetic nucleosides. LXVI. Studies on the synthesis of cis-2,3-diamino sugars. VI. Neighboring group reactions with methyl 4,6-0-benzylidene-3-deoxy-2-0-methylsulfonyl-3thioureido-a-D-glucopyranoside, J. Org. Chem., 30 (1965) 4045-4048. 

Neighboring-group participation reactions by sulfur and nitrogen functions have also been observed for deoxyhalogeno sugars. An example is the formation of the anhydride 146, which possesses an oxathiabicyclo[2.2.2]octane ring-system constrained in a boat-like conformation, on treatment of methyl 4-0-benzoyl-2-S-benzoyl-6-bromo-6-deoxy-2-thio-Q -D-altropyranoside (145) with methanolic... 

The acceptor should have only one unprotected OH-group, which accepts another carbon atom to build a new bond. If there is more than one unprotected OH-group it is necessary to take advantage of the different reactivity of these groups under optimized conditions. The unique reactivities depend on the sugar itself and for example the neighboring groups to this reaction center. 

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