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

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.