Synthesis and enantiomeric recognition ability of 22-crown-6 ethers derived from rosin acid and BINOL

Four novel chiral 22-crown-6 ethers 6a–b, 7a–b bearing hydroxyl side groups derived from rosin acid and BINOL were prepared in optically pure forms, and their enantiodiscriminating abilities towards protonated primary amines and amino acid methyl ester salts were examined by UV–vis titration methods. These receptors exhibited good chiral recognition towards the isomers (up to KD/KL = 6.02, ΔΔG0 = 4.45 kJ mol−1) and showed different complementarity to various chiral guests.

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[4α-Hydroxymethyl-13-isopropyl-16αH-atis-13-ene-15β,16β-dimethyl]-(S)-BINOL-22-C-6C52H66O7[α]D = −93.3 (c 0.1, acetone)Source of chirality: (S)-2,2′-dihydroxy-1,1′-binaphthyl (BINOL) and maleopimaric acidAbsolute configuration: (4R,5R,8S,9R,10R,15R,16R,1′S)

[4α-Hydroxymethyl-13-isopropyl-16αH-atis-13-ene-15β,16β-dimethyl]-(R)-BINOL-22-C-6C52H66O7[α]D = +65.7 (c 0.1, acetone)Source of chirality: (R)-BINOL and maleopimaric acidAbsolute configuration: (4R,5R,8S,9R,10R,15R,16R,1′R)

[4α-Hydroxymethyl-13-isopropyl-16βH-atis-13-ene-15β,16α-dimethyl]-(S)-BINOL-22-C-6C52H66O7[α]D = −39.0 (c 0.1, acetone)Source of chirality: (S)-BINOL and fumaropimaric acidAbsolute configuration: (4R,5R,8S,9R,10R,15R,16S,1′S)

[4α-Hydroxymethyl-13-isopropyl-16βH-atis-13-ene-15β,16α-dimethyl]-(R)-BINOL-22-C-6C52H66O7[α]D = −35.6 (c 0.1, acetone)Source of chirality: (R)-BINOL and fumaropimaric acidAbsolute configuration: (4R,5R,8S,9R,10R,15R,16S,1′R)