Organoammonium salts of dipeptide-derived chiral triamines or diamines with TfOH catalyzed
the enantioselective 1,3-dipolar cycloaddition reactions of α-acyloxyacroleins with
nitrones to give the corresponding adducts in good yields (up to 96%) and with high
diastereo- and enantioselectivities (up to 89% ee). Although α-(p-methoxybenzoyloxy)acrolein is rather unstable under the reaction conditions, α-(3-pyrroline-1-carbonyloxy)acrolein
is stable enough to be smoothly converted into the corresponding adducts with the
aid of the chiral organoammonium salt catalysts.
Key words
acyloxyacroleins - 1,3-dipolar cycloaddition - isoxazolidines - nitrones - organocatalysis
- asymmetric catalysis