Potassium Hexachloroosmate(IV)-Zinc


[16871-60-6]  · Cl6K2Os  · Potassium Hexachloroosmate(IV)-Zinc  · (MW 481.10) (Zn)

[7440-66-6]  · Zn  · Potassium Hexachloroosmate(IV)-Zinc  · (MW 65.39)

(catalyst for the cycloadditive dimerization of a,b-unsaturated ketones1)

Physical Data: K2OsCl6: mp dec.

Solubility: K2OsCl6: sol EtOH, MeOH.

Form Supplied in: K2OsCl6: hydrated crystals. Zn: powder. Both are commercially available.

Purification: K2OsCl6: recrystallized from hot dilute aqueous HCl. Zn: stirred with 2% aqueous HCl (3 L kg-1 Zn dust) for 1 min, filtered, washed with 2% HCl (3 L), three times with distilled water (1 L each), twice with 95% ethanol (1 L each), and once with diethyl ether (2 L), and then dried under vacuum. The reagents, along with the substrate, are mixed prior to reflux.

Handling, Storage, and Precautions: zinc dust is flammable.

Dimerization-Cyclopentannulation of Enones.

Treatment of a,b-unsaturated ketones with potassium hexachloroosmate(IV) and Zinc leads to the reductive dimerization-cyclization product, the cyclopentanol derivative, in nearly quantitative yield (eq 1).1 This unique transformation has unfortunately only been examined for two substrates, dibenzylideneacetone and 1,3-diphenyl-2-propenone.

1. Rubezhov, A. Z. TL 1977, 2189.

James W. Herndon

University of Maryland, College Park, MA, USA

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