Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

Abstract

New chiral atropisomeric biphenyl diols 3, 4 and 6 containing additional peripheral chiral centers with different steric bulkiness and/or electronic properties were synthesized. The X-ray crystal structure of 3 shows the formation of a supramolecular structure whereas that of 6, containing additional CF3 substituents, shows the formation of a monomeric structure. Diols 1–6 were found to be active organocatalysts in oxo-Diels–Alder reactions in which 2 recorded a 72% ee with trimethylacetaldehyde as a substrate.

Keywords

• asymmetric organocatalysis
• axial chirality
• biaryls
• hydrogen bond
• oxo-Diels–Alder reaction