Petasis enantioselective organocatalytic

Scheme 6.47 The enantioselective organocatalytic Petasis reaction among salicylaldehydes, amines, and organoboronic acids described by Yuan and coworkers [66].

The enantioselective, organocatalytic variant of the Petasis reaction, developed by Takemoto and coworkers from the University of Kyoto, represents a breakthrough in the synthesis of enantiopure 1,2-dihydroquinolines. As mentioned before, this structural unit is present in many natural products and biologically active compounds, and therefore an effective and short synthetic route via the Petasis-type reaction to enantiopure compounds in this class is a major leap forwards. Screening of the new thiourea catalysts in the Takamoto group resulted in a highly effective catalyst 13, specifically designed for the Petasis reaction. 

Later, Schaus group reported a new organocatalytic enantioselective example of Petasis reaction employing chiral biphenol-derived diol 30 as effective catalyst to promote... 

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