Cerium chloride quinones

A variant on iodine deprotections is a report on the cleavage of PMB ethers by a mixture of cerium(III) chloride heptahydrate and sodium iodide in refluxing acetonitrile.210 A proposed mechanism involves polarization of the ethereal link (158, Scheme 43), followed by generation of a quinone-like species, and attack by nucleophilic iodide to afford p-methoxybenzyl iodide. 

Treatment of 4concentrated sulfuric acid in trilluo-roacetic acid to give 443. These relatively low yields of two steps, 39 and 36%, respectively, were avoided subsequently by the direct reaction of 440 and 441 in the presence of cerium(III) chloride in air to give the cyclized product 443 in 73% )rield. The quinone 443 was reacted with V, A-dimethyl-formamide diethyl acetal to form 444, Which was treated with ammonium... 

Cellosolve s. Ethyl Cellosolve Cephalins 16, 274 Cerium(lll) chloride —, catalysis of reactions with quinones 18, 393 Cerium(IV) nitrate 16, 248 Cesium fluoride 17, 800 ... 

The scope of the catalytic potential of the cerium(III) ion was intimated by Pratt (1962) in an investigation of the addition of aromatic amines to quinones. Use of hydrated cerous chloride in place of cupric acetate as an oxygen carrier in the oxidation of byproduct hydroquinone resulted in improved yields and easier product separation from metal complexes. 

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