Enantioselective α-tosyloxylation of ketones catalyzed by spirobiindane scaffold-based chiral iodoarenes

Enantiomerically pure iodoarene (S)-2 and its derivatives (S)-3 to (S)-18 with a spirobiindane scaffold have been synthesized. The evaluation of these new chiral iodoarenes as catalysts in the enantioselective α-tosyloxylation of ketones was performed using m-CPBA as a stoichiometric oxidant, and the synthetically useful α-tosyloxylated ketones were obtained in up to 58% enantiomeric excess (ee).

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(S)-1-Oxo-1-phenylpropan-2-yl 4-methylbenzenesulfonateC16H16O4S53% ee[α]D25=-5.2 (c 0.5, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (S)

1-Oxo-1-phenylbutan-2-yl 4-methylbenzenesulfonateC17H18O4S58% ee[α]D25=-8.2 (c 0.9, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

2-Oxo-1,2-diphenylethyl 4-methylbenzenesulfonateC21H18O4S13% ee[α]D25=-33.0 (c 1.0, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

1-Cyclohexyl-1-oxopropan-2-yl 4-methylbenzenesulfonateC16H22O4S22% ee[α]D25=-7.75 (c 0.8, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

1-Oxo-1-phenylpropan-2-yl 2,4,6-triisopropylbenzenesulfonateC24H32O4S50% ee[α]D25=-4.8 (c 0.5, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown