Axially chiral C2-symmetric N-heterocyclic carbene (NHC) palladium complex-catalyzed asymmetric α-hydroxylation of β-keto esters

Axially chiral C2-symmetric N-heterocyclic carbene (NHC) palladium diaquo complexes 1a and 1b, derived from (R)-BINAM, are effective catalysts for the enantioselective α-hydroxylation of β-keto esters using oxaziridine 2a as the oxidant to give the corresponding products in high yields along with moderate enantioselectivities.

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(R)-Methyl 2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC11H10O4Ee = 61%[α]D20=-45.2 (c 1.0, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-Isopropyl 2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC13H14OEe = 37%[α]D20=-21.7 (c 0.70, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-tert-Butyl 2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC14H16OEe = 18%[α]D20=-9.6 (c 0.75, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-Benzyl 2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC17H14O4Ee = 30%[α]D20=-8.1 (c 1.1, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-Methyl 5-chloro-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC11H9ClO4Ee = 61%[α]D20=-64.2 (c 0.75, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

Ethyl 5-chloro-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC12H11ClO4Ee = 51%[α]D20=-69.4 (c 0.7, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-Methyl 6-bromo-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC11H9BrO4Ee = 43%[α]D20=-12.9 (c 1.4, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-Ethyl 6-bromo-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylateC12H11BrO4Ee = 51%[α]D20=-9.6 (c 1.4, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

(R)-Methyl 2-hydroxy-1-oxo-1,2,3,4-tetrahydronaphthalene-2-carboxylateC12H12O4Ee = 46%[α]D20=+7.7 (c 1.1, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (R)

Methyl 1-hydroxy-2-oxocyclopentanecarboxylateC7H10O4Ee = 14%[α]D20=-5.2 (c 0.3, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (S)