Salts oxoisoindolium

The catalytic activity of the oxoisoindolium salt 54 and 55 was compared to that of trityl tetrakis[pentafluorophenyl]borate salts in the addition reaction of enol acetate to benzaldehyde and glycosylation reaction (Scheme 59) [151, 152]. 

In order to enhance the catalytic activity of a carbocationic center, the novel Lewis acid 54 was designed by Mukaiyama [149-152]. The 1-oxoisoindolium-based carbenium salt 54 [149], possessing a weak coordinating borate counter anion, proved to be a very active catalyst in the aldoUzation (Scheme 58) [150]. The Mukaiyama aldol reaction was catalyzed by 1 mol% of salt 54 and proceeded in up to 97% yield in 30 min. 

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