Asymmetric Diels–Alder reaction using a new chiral β-nitroacrylate for enantiopure trans-β-norbornane amino acid preparation

The main nitronorbornene adduct derived from the asymmetric Diels–Alder reaction of (S)-benzyl-4-(3-(3-nitroacryloyloxy)-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoate (S)-1 and cyclopentadiene was isolated and transformed to afford the enantiopure bicyclic β-amino acid (1S,2R,3R,4R)-trans-β-norbornane amino acid 9. The enantiomer (1R,2S,3S,4S)-9 could be obtained by the same synthetic route by using the chiral auxiliary (R)-1.

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[N-(4-Benzyloxycarbonylphenyl)-4,4-dimethyl-2-oxopyrrolidin-3-yl] 3-nitrobicyclo[2.2.1]hept-5-ene-2-carboxylateC28H28N2O7De = 99%[α]D = −102 (c 0.9, CH2Cl2)Source of chirality: (S)-benzyl-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoateAbsolute configuration: (1R,2R,3R,4S,3′S)

[N-(4-Carboxyphenyl)-4,4-dimethyl-2-oxopyrrolidin-3-yl] 3-tert-butoxycarbonylaminobicyclo[2.2.1]heptane-2-carboxylateC26H35N2O7De = 99%[α]D = −14 (c 1.5, CH2Cl2)Source of chirality: (S)-benzyl-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoateAbsolute configuration: (1S,2R,3R,4R,3′S)

3-tert-Butoxycarbonylaminobicyclo[2.2.1]heptane-2-carboxylic acidC13H22NO4De = 99%[α]D = −22 (c 0.9, CH2Cl2)Source of chirality: (S)-benzyl-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoateAbsolute configuration: (1S,2R,3R,4R)