Chalcogenide-TiCl4 Mediated System

Kataoka et were the first to investigate the chalcogeno-MBH reaction 

the same authors examined the applicability of 2,6-diphenyl-4/f-chalcogenopyran-4-ones 292 and 2,6-diphenyl-4Ff-chalcogenopyran-4-thiones 

On the basis of all these transformations, Kataoka et al. have reinvestigated the products and reaction mechanism of the chalcogeno-MBH reaction. They found that, when purifying the product from the reaction of p-nitrobenzaldehyde with methyl vinyl ketone by column chromatography on silica gel, chloromethyl aldol 251a was obtained in 95% yield as a mixture of 

Ch Me2S, 74% yield, symanti = 7A 293a, 95% yield, syir.anti = 3 1 

During our studies on the chalcogeno-MBH reaction between aldehydes and methyl vinyl ketone (MVK), we found that this reaction can be drastically 

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