Planar Chiral PHANOLs as Organocatalystsfor the Diels-Alder Reaction via Double Hydrogen-Bondingto a Carbonyl Group

Authors:
  • DBD. Christopher Braddock
    D. Christopher Braddock
  • IMIain D. MacGilp
    Iain D. MacGilp
  • BPBenjamin G. Perry
    Benjamin G. Perry
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Abstract
Planar chiral PHANOLs have been shown to catalyze Diels-Alder reactions of a,b-unsaturated aldehydes and ketones with various dienes. Rate accelerations of up to ca. 30-fold were obtained using the electron deficient 4,12-dihydroxy-7,15-dinitro[2.2]paracyclophane as a catalyst. It is proposed that the carbonyl group of the dienophile is activated via a double hydrogen-bonding mode. Although the PHANOLs are inherently chiral, little or no asymmetric induction was observed when using enantiopure (R)-PHANOL.