Montmorillonite aldol condensations

Circulation flow system, measurement of reaction rate, 28 175-178 Clausius-Clapeyron equation, 38 171 Clay see also specific types color tests, 27 101 compensation behavior, 26 304-307 minerals, ship-in-bottle synthesis, metal clusters, 38 368-379 organic syntheses on, 38 264-279 active sites on montmorillonite for aldol reaction, 38 268-269 aldol condensation of enolsilanes with aldehydes and acetals, 38 265-273 Al-Mont acid strength, 38 270-271, 273 comparison of catalysis between Al-Mont and trifluorometfaanesulfonic acid, 38 269-270... 

There has been a quite limited number of reports of clay-catalysed aldol condensations. One of the more interesting of these is the aluminium-exchanged montmorillonite (Al3+-mont) catalysed cross-aldol reaction of silyl enol ethers with aldehydes (Reaction 6).34 The reaction proceeded smoothly under mild conditions to give the corresponding aldol adduct in good yield. 

AldolCondensations. Cation-exchanged montmorillonites accelerate the aldol condensation of silyl enol ethers with acetals and aldehydes. Similarly, the aldol reaction of silyl ketene acetals with electrophiles is catalyzed by solid-acid catalysts. Neither report discussed the use of iron montmorillonite for these reactions however, some reactivity is anticipated. 

---