Development of mild methodologies for the synthesis of chiral amines or functional groups derived from them is crucial for pharmacy and agrochemistry. More specifically, optically active aminonaphthols, with two functional groups in sight, are important synthons for the synthesis of new heterocycles. Additionally, 3-amino-2-oxindole skeleton exists in many biologically active natural products. Enantioselective aza-Friedel Crafts reaction of naphthols with isatin-derived ketimines is a direct strategy combining privileged aminonaphthol and tetrasubstituted 3-amino-2-oxindole units in one. A new quinine-derived squaramide catalyzed aza-Friedel-Crafts reaction of <i>N</i>-alkoxycarbonyl isatin ketimines with naphthol afforded chiral tetrasubstituted 3-amino-2-oxindoles with excellent enantioselectivity up to greater than 99% <i>ee</i> and quantitative yields. To the best of our knowledge, this methodology is featured for being illustrative of efficient enantioselection in the presence of sterically hindered hydrocarbon substituents in squaramide organocatalyst.

New quinine-based squaramide catalyst and its evaluation in the asymmetric aza-Friedel-Crafts reactions of isatin-derived ketimines

253rd National Meeting (2017)

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