Tandem deprotection-aldol reaction with acids

I 6 Mechanistic Studies of Solid Acids and Base-Catalyzed Clean Technologies Table 6.1 Tandem deprotection-aldol reaction with acids and bases."... 

Table 2. Tandem Deprotection-Aldol Reaction with Acids and Bases...

Figure 2.26 Cascade reactions requiring both strong acid and basic Bronsted sites reaction scheme and pictorial representation of tandem deprotection-aldol reaction with different acids and basic steps using a combination of Ti -montmorillonite (Ti -mont) and hydrotalcite (HT). Elaborated from the results of Kaneda et al. [219], Source adapted from Centi and Perathoner [211].

A tandem reaction using Ti +-mont and HT that comprises deprotection and aldol condensation from malononitrile and benzaldehyde dimethyl acetal as starting materials is outlined in Table 2. The product is obtained only when both Ti + mont and HT are present and it is synthesized by Ti +-mont-catalyzed deacetalization of benzaldehyde dimethyl acetal, followed by the aldol reaction of malononitrile with benzaldehyde. When either Ti +-mont or HT was replaced by a homogeneous reagent such as p-toluenesulfonic acid or piperidine, neither the deacetalization nor the aldol reactions occurred to any great extent. 

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