Induced circular dichroism in chiral N-methyl amides possessing an achiral binaphthyl chromophore and its application to absolute configuration determination of aliphatic chiral amines

Induced circular dichroism (ICD) was observed in binaphthyl N-methyl amides of chiral primary amines. The CD spectra showed split curves centered at 225 nm. A good correlation was found between the sign of the exciton chirality of the binaphthyl derivative and the absolute configuration of the original amine. Furthermore, the screw sense of the two naphthyl groups in the most stable conformer obtained from molecular mechanics (MM) calculation was in agreement with those expected from the exciton chirality, indicating that the method based on MM calculations can be used to determine unknown absolute configurations of aliphatic chiral amines. The practical use of the present method was demonstrated by the determination of the absolute configurations of the natural products, d- and l-cycloserines.

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Methyl 3′-{[(1S)-1-cyclohexylethyl]carbamoyl}-2,2′-binaphthalene-3-carboxylateC31H31NO3Enantiomeric excess: 100%ee[α]D26=+7.4 (c 1.870, CHCl3)Source of chirality: (S)-(+)-1-CyclohexylethylamineAbsolute configuration: (S)

Methyl 3′-{[(2S-3,3-dimethylbutan-2-yl]carbamoyl]-2,2′-binaphthalene-3-carboxylateC29H29NO3Enantiomeric excess: 100%ee[α]D26=+0.2 (c 2.020, CHCl3)Source of chirality: (S)-(+)-3,3-Dimethyl-2-butylamineAbsolute configuration: (S)

Methyl 3′-[(2S)-butan-2-ylcarbamoyl]-2,2′-binaphthalene-3-carboxylateC27H25NO3Enantiomeric excess: 100%ee[α]D26=-6.2 (c 4.220, CHCl3)Source of chirality: (S)-(+)-sec-ButylamineAbsolute configuration: (S)

Methyl 3′-[(2R)-hexan-2-ylcarbamoyl]-2,2′-binaphthalene-3-carboxylateC29H29NO3Enantiomeric excess: 100%ee[α]D20=-17.7 (c 0.884, CHCl3)Source of chirality: (R)-2-AminohexaneAbsolute configuration: (R)

Methyl 3′-{[(1S,2S,3S,5R)-2,6,6-trimethylbicyclo[3.1.1]hept-3-yl]carbamoyl}-2,2′-binaphthalene-3-carboxylateC33H33NO3Enantiomeric excess: 100%ee[α]D20=+25.2 (c 0.266, CHCl3)Source of chirality: (1S,2S,3S,5R)-(+)-IsopinocampheylamineAbsolute configuration: (1S,2S,3S,5R)

Methyl 3′-{[(1S)-1-cyclohexylethyl](methyl)carbamoyl}-2,2′-binaphthalene-3-carboxylateC32H33NO3Enantiomeric excess: 100%ee[α]D20=-23.8 (c 0.248, CHCl3)Source of chirality: (S)-(+)-1-CyclohexylethylamineAbsolute configuration: (S)

Methyl 3′-{[(2S)-3,3-dimethylbutan-2-yl](methyl)carbamoyl]-2,2′-binaphthalene-3-carboxylateC30H31NO3Enantiomeric excess: 100%ee[α]D26=-10.0 (c 2.180, CHCl3)Source of chirality: (S)-(+)-3,3-Dimethyl-2-butylamineAbsolute configuration: (S)

Methyl 3′-[(2S)-butan-2-yl(methyl)carbamoyl]-2,2′-binaphthalene-3-carboxylateC28H27NO3Enantiomeric excess: 100%ee[α]D20=+9.0 (c 0.748, CHCl3)Source of chirality: (S)-(+)-sec-ButylamineAbsolute configuration: (S)

Methyl 3′-[(2R)-hexan-2-yl(methyl)carbamoyl]-2,2′-binaphthalene-3-carboxylateC30H31NO3Enantiomeric excess: 100%ee[α]D26=+7.4 (c 1.870, CHCl3)Source of chirality: (R)-2-AminohexaneAbsolute configuration: (R)

Methyl 3′-{methyl[(1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]hept-3-yl]-carbamoyl}-2,2′-binaphthalene-3-carboxylateC34H35NO3Enantiomeric excess: 100%ee[α]D26=+0.2 (c 2.020, CHCl3)Source of chirality: (1R,2R,3R,5S)-(−)-IsopinocampheylamineAbsolute configuration: (1R,2R,3R,5S)

Methyl 3′-{[(4R)-3-oxoisoxazolidin-4-yl]carbamoyl}-2,2′-binaphthalene-3-carboxylateC26H20N2O5Enantiomeric excess: 100%ee[α]D26=-6.2 (c 4.220, CHCl3)Source of chirality: d-cycloserineAbsolute configuration: (R)

3′-{Methyl[(4R)-2-methyl-3-oxoisoxazolidin-4-yl]carbamoyl}-2,2′-binaphthalene-3-carboxylateC28H24N2O5Enantiomeric excess: 100%ee[α]D29=+51.2 (c 0.43, CHCl3)Source of chirality: d-cycloserineAbsolute configuration: (R)