Acetic acid, reaction with glycals

Reaction of AcOF with glycals has been developed. Rozen and coworkers observed that elemental fluorine, which is practically insoluble in, and non-reactive with, acetic acid, gives rise to the active species, AcOF,... 

Acid-catalyzed organic reactions by using clays continue to attract attention, and many reports on acetalization have appeared. The formation of C-glycosides by the reaction of glycals with enol silyl ethers, acetates, and allylsilanes is efficient (53-97%). ... 

CAN in combination with iodine or an iodide has been demonstrated to be a powerful iodination reagent. Stereoselective iodo-acetoxylation of glycals using sodium iodide and CAN in a mixture of MeCN and acetic acid has been achieved. In a similar fashion, the reaction of a. -unsaturated ketones or esters with iodine and CAN in alcohol affords the corresponding -alkoxy-a-iodoketones or esters in good yields. The regioselective iodination of p)frazoles and an alkoxybenzene mediated by CAN has been reported. 

Notes and discussion. The traditional (and indeed the original) method of the synthesis of glycals is via reductive elimination of an acylated glycosyl halide. This reaction leads to the formation of the acetylated glycal, which can then be de-acetylated and further functionalised. A variety of reducing conditions have been reported zinc/acetic acid with or without platinic chloride has been most commonly... 

A convenient synthesis of L-2-sorbar (2,6-anhydro-3-deoxy-L-rArco-hex-2-enitol) starting from 2,5-anhydro-D-galactitol has been reported. Thus treatment of the latter with 2,2-dimethoxypropane (to produce a mixture of di- and triacetals) then potassium /err-butoxide in DMSO (to effect elimination of acetone) gave glycal 4. Its reaction with methanolic acetic acid yielded L-2-sorbal . In... 

At reflux the reaction of a glycal 49 with acetic acid and NIS gives a 1 1 mixture of P-D-gluco 50 and a-D-manno 51 isomers. After separation, the manno isomer can be reduced back to the starting glycal with lithium iodide in tetrahydrofuran... 

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