Tropylium Salt-Promoted Vinylogous Aza-Michael Addition of Carbamates to para-Quinone Methides: Elaboration to Diastereomerically Pure α,α′-Diarylmethyl Carbamates
Highly enantioselective organocatalytic Michael addition of tritylthiol to N-o-QM intermediates generated in situ at the H2O/DCM interface is presented.
A bifunctional squaramide catalyzed the enantioselective Michael addition of pyrazol-3-
ones to ortho-quinone methides, generated in situ from 2-(1-tosylalkyl)phenols is presented. The corresponding
chiral pyrazolones are obtained with good to excellent yields (27-98%) and enantiomeric excess
(14-99% ee).
Tropylium Salt-Promoted Vinylogous Aza-Michael Addition of Carbamates to para-Quinone Methides: Elaboration to Diastereomerically Pure α,α′-Diarylmethyl Carbamates
