Novel strategy for the synthesis of chiral pseudo-ortho-substituted hydroxy[2.2]paracyclophane-based ligands from the resolved 4-bromo-12-hydroxy[2.2]paracyclophane as a parent compound

A simple and efficient resolution of racemic 4-bromo-12-hydroxy[2.2]paracyclophane into its enantiomers via diastereomeric esters with (1S)-(−)-camphanic acid was carried out. New synthetic routes to enantiomerically pure 4,12-dihydroxy- and 4-hydroxy[2.2]paracyclophanes starting from the enantiomers of an intermediate 4-bromo-12-hydroxy[2.2]paracyclophane are proposed.

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4-Bromo-12-camphanoyloxy[2.2]paracyclophaneC26H27BrO4Ee >99%[α]D20=-54.8 (c 0.75, C6H6)Source of chirality: optical resolutionAbsolute configuration: (Rp,S)

4-Bromo-12-camphanoyloxy[2.2]paracyclophaneC26H27BrO4Ee >99%[α]D20=+19.0 (c 0.97, C6H6)Source of chirality: optical resolutionAbsolute configuration: (Sp,S)

4-Bromo-12-hydroxy[2.2]paracyclophaneC16H15BrOEe >99%[α]D20=+24.4 (c 0.80, C6H6)Source of chirality: (Sp,S)-4-bromo-12-camphanoyloxy[2.2]paracyclophaneAbsolute configuration: (Sp)