Abstract
Hypervalent λ3-iodanes have become a prominent tool for halofunctionalizations of alkenes. Despite
many examples of asymmetric fluorinations reported lately, the corresponding enantioselective
chlorination reactions using iodoresorcinol-based catalysts are significantly less
developed, with only one example known to date. Here, we show how competing aromatic
chlorination of the iodoarene catalyst is a significant obstacle in these transformations,
hinting towards a conceptual issue with this well-established catalyst class for enantioselective
chlorinations. Consequently, the reaction conditions and the catalyst design must
be adapted to facilitate an effective chirality transfer. Hence, attention should
be paid when selecting the oxidizing agent, the stoichiometry, and careful reaction
analysis must be conducted to identify the factual catalytically active species.
Key words
chlorination - hypervalent iodane catalysis - asymmetric reactions - iodoresorcinols
- rearrangement