Iodination, levoglucosenone

Addition of iodine to levoglucosenone has been conveniently performed by the treatment of this enone with a solution of iodine in anhydrous pyridine (17), resulting in the formation of 3-iodolevoglucosenone in moderate (55%) yield. 

Similar functionalization, but at the C-3 position in levoglucosenone, via iodine addition to the conjugate position and then nucleophilic displacement of iodine with a reactive thiol represents another valuable stereoselective strategy to a/p (l-3)-linked 5>thiodisaccharides. 

Scheme 4. Stereoselective Sn2 displacement of iodine in 3-iodo-levoglucosenone by 1-thio-p-D-glucose with stereoselective formation of (1-3)-S-thiodisaccharides. Ref. 4...

A particularly interesting approach to the l,6 3,4-dianhydro-D-talopyranose was reported by Matsumoto and coworkers (63). The reaction sequence starts from the allylic alcohol (reduced levoglucosenone), which upon treatment with iodine and silver acetate in acetic acid, followed by heating with water and neutralization with methanolic ammonia, forms two compounds (Scheme 13). 

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