Sugars 6-bromo-6-deoxy

The synthesis of halodeoxy sugars has also been achieved by reaction of sugar phosphorodiamido and phosphonamido derivatives with alkyl halides (83). Heating equimolar amounts of 6-(tetraethylphosphoro-diamido)-l,2 3,4-di-0 isopropylidene-D-galactose with methyl iodide (and benzyl bromide) at 140°C. for 4 hours afforded the 6-deoxy-6-iodo (74b) (75%) and 6-bromo-6-deoxy (74c) (56%) derivatives, respectively. 

Stereospecific dependencies of the nonselective relaxation-rates for other protons in a sugar molecule may be seen in the data for a set of 3,4,6-tri-O-acetyl-l-0-benzoyl-2-deoxy-2-bromo-D-hexopyranose derivatives (40-42), as well as other 2-halogeno derivatives. A comparison of their... 

The bromodeoxyaldonolactones have been used for the preparation of aminodeoxy aldonic acids and aminodeoxy sugars via azido derivatives (45,46). Likewise, a- and /J-aminopolyhydroxy acids have been prepared by treatment of the bromodeoxyaldonolactones with liquid ammonia (47). Thus, 3-amino-3-deoxy-D-threonic acid and 3-amino-3-deoxy-D-arabin-onic acid (40b) were obtained from 2-bromo-2-deoxy-L-threono- or D-xy-lono-1,4-lactone (38). It was shown that 2,3-epoxy carboxamides (namely, 39) are intermediates of the reaction. Heating at 90° for long periods led to the 3-amino-3-deoxyaldonamides, which upon acid hydrolysis yielded the corresponding aldonic acids. 

Ring contraction of readily available sugar derivatives has been used in synthetic approaches towards C-nucleosides, and the first ring contraction under acidic conditions of benzylated 2-bromo-2-deoxy-1,5-lactones to give... 

Sugars containing a carbon-phosphorus bond have been prepared by application of the Michaelis-Arbuzov reaction to bromodeoxy sugars. Thus, the reaction of 5-bromo-5-deoxy-l,2-0-isopropylidene-3-O-methyl-a-D-xylofuranose (131) with triethyl phosphite yields the corresponding diethyl phosphonate (132) compound 132 was employed for the synthesis of a sugar derivative having phosphorus as... 

If an appropriately situated, unsubstituted hydroxyl group is available, anhydro-ring formation usually takes precedence over substitution or elimination. Thus, with alkali, the bromo-, chloro-, and iodo-deoxy sugars react analogously to sulfonic ester derivatives148 to afford epoxides in good yield.22,169 It has been established170 that l,2 5,6-dianhydro-D-mannitol is formed in aqueous solutions of... 

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... 

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