A chiral pool based approach to antipodes of α-cuparenone

A synthetic route to both antipodes of α-cuparenone was achieved from the readily available chiral pool starting material l-malic acid and involved cyclopentannulation as the key step.

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(S)-Dimethyl 2-(benzyloxy)succinateC13H16O5[α]D25=-70.4 (c 1.08, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (2S)

(S)-2-(Benzyloxy)butane-1,4-diolC11H16O3[α]D25=-14.3 (c 1.26, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (2S)

(S)-(((1,4-Diiodobutan-2-yl)oxy)methyl)benzeneC11H14I2O[α]D25=-62.7 (c 1.02, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (2S)

(1S,3S)-3-(Benzyloxy)-1-(p-tolyl)cyclopentanecarbonitrileC20H21NO[α]D25=-3.5 (c 1.73, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (1S,3S)

(1R,3S)-3-(Benzyloxy)-1-(p-tolyl)cyclopentanecarbonitrileC20H21NO[α]D25=+8.4 (c 6.68, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (1R,3S)

1-((1R,3S)-3-(Benzyloxy)-1-methylcyclopentyl)-4-methylbenzeneC20H24O[α]D25=-29.7 (c 1.82, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (1R,3S)

1-((1S,3S)-3-(Benzyloxy)-1-methylcyclopentyl)-4- methylbenzeneC20H24O[α]D25=+18.1 (c 2.1, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (1S,3S)

(R)-3-Methyl-3-(p-tolyl)cyclopentanoneC13H16O[α]D25=+13.3 (c 4.0, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (R)

(S)-2,2,3-Trimethyl-3-(p-tolyl)cyclopentanoneC15H20O[α]D25=+170.1 (c 1.08, CHCl3)Source of chirality: l-(−)-malic acidAbsolute configuration: (S)