Ketenes thioacetal monoxides

Hermann and colleagues218,219 found that treatment of ketene thioacetal monoxides 172 and 173, with enamines, sodium malonates, /J-dicarbonyl compounds and lithio-... 

The syntheses by Ban and co-workers of both Na-acetylaspidospermidine (180) and deoxylimapodine (181) (Scheme 32) utilize the important pentacyclic ketone (182), prepared earlier. The critical stage in both syntheses is a Michael reaction, apparently stereospecific, of (182) with methyl vinyl sulphone [-> (180)] and keten thioacetal monoxide [—>(181)], respectively. The later stages in the synthesis are unexceptional. Mercuric acetate oxidation of deoxylimapodine enabled the first synthesis of iVa-acetylaspidoalbidine (183) to be completed. ... 

The terminally oxygenated two-carbon side chain was inserted by Michael addition of ketene thioacetal monoxide to the now familiar vinyl-ogous amide 428 followed by deacetalization to give the aldehyde 447 in 75% yield. In fact, the intermediate 448 existed as two separable isomers, but because each was converted to 447, they were assumed to be isomers at C-18. 

The first examples of the use of the Knoevanagel-type condensation for the synthesis of a,p-unsaturated sulfoxides were made by Ogura and Tsuchihashi, who prepared racemic ketene thioacetal monoxides by the condensation of methyl... 

Ketene dimethyl thioacetal monoxide, 6, 311 312. Convenient preparation1 ... 

Schlessinger has shown that the addition of ester enolates to sulfur stabilized acceptors, e.g. ketene di-thioacetal monoxide (151) and methyl a-(methylthio)acrylate (187), is highly efficient for the synthesis of Y-ketoesters.148 Similarly, Ahlbrecht and Seebach have reported that amide and ester enolate additions to nitrogen stabilized acceptors, e.g. nitroalkenes (40) and 2-(/V-methylanilino)acrylonitrile (59 Scheme 72), are highly efficient.149... 

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