Cyclohexanone ethylenethioketal

Cleavage of tkhkeuds. Protection of ketones and aldehydes by conversion to thioketals is rarely u.sed because thioketals are resistant to both acid- and base-catalyzed hydrolysis. Use of mercuric salts has been the most useful procedure known (1, 654 2, 182 3, 136). Japanese chemists now report that cleavage can be effected readily through alkylation with triethyloxonium fluoroborate. Thus alkylation of cyclohexanone ethylenethioketal (I) with the reagent affords the salt (2). Alkaline hydrolysis of (2) gives cyclohexanone in only 36% yield. However, if the salt (2) is shaken with 3% CUSO4 solution in methylene chloride, cyclohexanone is obtained in 81 % yield. 

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