Unsaturated sugars halogen addition

The addition of halogen fluoride to unsaturated carbohydrates gives a mixture of cis- and /ra .t-adducts similar to other electrophilic additions to unsaturated sugars. 

The increased availability of methods for the preparation of unsaturated sugars107 has stimulated interest in addition reactions of these compounds the use of unsaturated carbohydrate derivatives as precursors for specifically halogenated sugars has been widely exploited. 

Copolymers of PHAs containing repeating units with unsaturated or brominated pendant side chains have been obtained from cultures of Pseudomonas oleovorans grown on mfactures of octanoic acid and undecenoic acid or 11-bromoundecanoic acid as carbon sources. These polymers, bearing reactive functionalities, have been used to graft acetylated maltosyl units either by anti-Markovnikov addition to the double bond or SN2 substitution of the halogen. De-O-acetylation of the sugar moieties yielded PHAs with new properties. ... 

A number of -acyl- and thioureido-derivatives of 3 -amino-3 -deoxythymidine have been prepared. 1 0 Michael addition of phthalimide to enal (81) was used in the synthesis of the 3 -amino-2 ,3 -dideoxyhexo-furanose nucleosides (82) (all four isomers, R=H, Me, halogen),191 and a similar enal prepared by mercuric-ion catalysed hydrolysis of L-rhamnal was used in the same way to make the L-acosaminyl nucleoside (83) and its -anomer, and the L-ristosaminyl systems (epimers at C-3 ). 2 Michael addition of 1,2,4-triazole to (81) led, after base-sugar condensation, to the triazolyl-substituted nucleosides (84, B=T, U), together with the analogous hexopyranose systems. 93 xhe imidazolyl nucleosides (85) can be made by reaction of 3 -amino-3 -deoxythymidine with l,4-dinitroimidazoles, 9 whilst the unsaturated imidazole nucleoside (87) was made by treating the phenylselenone (86) (see Section 6) with imidazole. 195... 

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