Potassium Iodide-Zinc/Copper Couple

KI-Zn/Cu
(KI)

[7681-11-0]  · IK  · Potassium Iodide-Zinc/Copper Couple  · (MW 166.00) (Zn/Cu)

[53801-63-1]

(agent for elimination of vicinal oxygen functionality1)

Physical Data: see entries for Potassium Iodide and Zinc/Copper Couple.

Vicinal Oxygen Elimination.1

Vicinal sulfonyloxy groups are eliminated by this reagent (eq 1). Although the reported yield from (1) is low, this procedure represented an improvement in both yield and reproducibility over previous methodology (zinc dust-sodium iodide).2 With different O-protection, however, the fairly vigorous conditions caused loss of the 4-benzoyl group of (2) (eq 2), although it is still noteworthy that, in both cases, epimerization was not observed. The reaction is reported1 to be slightly slower if Sodium Iodide is used in place of the potassium salt, although such a modification has been reported elsewhere3 as quite adequate to eliminate the diol monosulfonate (3) (eq 3).

This reductive elimination of vicinal disulfonates has also been reported with NaI alone4 in ketonic solvent, and with Sodium Anthracenide5 (for mesylates but not tosylates). With the exception, perhaps, of the latter, all of these comparable methods seem to be sufficiently mild to work effectively in the area of stereochemically sensitive molecules, the carbohydrates.

Related Reagents.

Sodium Iodide; Sodium Iodide-Copper; Zinc; Zinc-Acetic Acid; Zinc Iodide.


1. Fraser-Reid, B.; Boktor, B. CJC 1969, 47, 393.
2. Tipson, R. S.; Cohen, A. Carbohydr. Res. 1965, 1, 338.
3. Radatus, B. K.; Clarke, I. S. S 1980, 47.
4. (a) Yadav, J. S.; Rao, E. S.; Rao, V. S. SC 1989, 19, 705. (b) Bladon, P.; Owen, L. N. JCS 1950, 598.
5. Carnahan, J. C., Jr.; Closson, W. D. TL 1972, 3447.

Peter Ham

SmithKline Beecham Pharmaceuticals, Harlow, UK



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