ChemInform Abstract: Oxidative Acetoxylation of Silylated Enol Ethers.

Abstract

ChemInform Abstract The reactions between equimolar quantities of phenyliodoso diacetate (II) and the trimethylsilylprotected enols (I), (V), (VIII) or (XI) may take two different routes: substitution of one vinylic proton by an acetoxy group, as can be seen by the formation of the products (III) or (VI), or bis-acetoxylation of the trimethylsilyloxysubstituted alkene bonds, as can be seen by the formation of the products (IV), (IX) or (XII). The compounds (IX) and (XII) are not obtained in a pure state. Treatment of the products formed by vinyl proton substitution or by bis-acetoxylation with BF3•Et2O affords α-acetoxy ketones, e.g. (VII), (X) or (XIII). This reaction may constitute an access to the regiospecific synthesis of α-acetoxy ketones.

Palladium-catalyzed oxidative C–O cross-coupling of ketene dithioacetals and carboxylic acids

“…Pb(OAc) 4 proved to be an efficient acetoxylating reagent for this purpose though the employment of a large amount of highly toxic lead salt is not encouraged. 4d,e,5 Additionally, the acetoxylation was found to accompany with a-iodination and N-arylation of enol silyl ethers 3 when treating enol silyl ethers with PhI(OAc) 2 . The acetoxylation of acyclic enamines was also observed when performing the homocoupling of them by the action of PhI(OAc) 2 in the presence of BF 3 $Et 2 O.…”

“…1,2 However, direct olenic C-H oxygenation has received less attention likely due to the large driving force for addition reaction or allylation reaction of the double bonds upon coupling reaction. [1][2][3][4][5][6][7] Limited methodologies have been developed for the acetoxylation of some active olens (e.g., enol silyl ethers, 3 enamines, 4 ketene N/S,S-acetals 5 ). Pb(OAc) 4 proved to be an efficient acetoxylating reagent for this purpose though the employment of a large amount of highly toxic lead salt is not encouraged.…”