129. From Cationic to Anionic Helicenes: New Reactivity through Umpolung
     David Conreaux, Nathalie Mehanna, Christelle Herse, Jérôme Lacour
     J. Org. Chem. 2011, 76, 2716-2722

Using a two-step reduction / metalation procedure, highly stable chiral carbenium ions are transformed into reactive carbanion intermediates. Interesting polar ketone and thioamide products are the results of this umpolung that occurs with complete retention of configuration of the helical backbone.

DOI : 10.1021/jo200071n 

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