Enantioselective indole aza-Claisen rearrangement

Maity, R Pemberton, R. R Tantillo, D. J. Tambar, U. K. Bronsted Acid Catalyzed Enantioselective Indole Aza-Claisen Rearrangement Mediated by an Arene CH-O Interaction. J. Am. Chem. Soc. 2013,135,16380-16383. 

A Br0nsted-acid-catalysed enantioselective indole aza-Claisen rearrangement has been applied for the synthesis of chiral 3-amino-2-substituted indoles where an arene CH-O interaction is the source of activation and stereoinduction (Scheme 24) ... 

Aminoindole 166 was found to undergo a catalytic, enantioselective aza-Claisen rearrangement upon heating in toluene with chiral phosphoric acid 168 to afford 2,3-disubstituted indole 167. A variety of substituents were competent under the reaction conditions and both yields and ee s were excellent in most examples. It was proposed that the rearrangement was accelerated and transferred high enantioselectivity by an arene CH—O interaction between the C2 proton and the phosphate counterion of 168 (13JA16380). 

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