B rousted acidity

Schaus and coworkers have developed a general route to the Clerodane diter-pene core by the use of previously developed B rousted acid catalyzed asymmetric Morita-Baylis-Hillman (MBH) reaction/Lewis acid mediated ring-annulation process (Scheme 1.33) [31]. Excellent diastereoselectivity was achieved in the key MBH reaction in the presence of 10mol% of the chiral BINOL derivative (29), affording the key intermediate for the synthesis of Clerodane decalin core. 

Combination of super B rousted acid with simple Bronsted acid or Lewis acid would be a new system for acid catalysis in organic synthesis. The example of super BLA would be an interesting tool for selective organic transformations. We have already shown excellent examples in Scheme 1.3 using the Tf2NH-chiral Lewis acid combined system. Scheme 1.36 exemplifies some additional recent reactions based on pentafluorophenyl bis (triflyl)methane and chiral Lewis acid catalyst [38]. 

While Bronsted acids can activate electrophiles as electron acceptors as described earlier, super B rousted acids are capable of additional unexpected activation of electrophiles by further protolytic interaction. Acetyl cation (C=0 ) and nitronium... 

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