Asymmetric “Acetylenic” [3+2] Cycloaddition of Nitrones Catalyzed by Cationic Chiral PdII Lewis Acid
Highly enantioselective [3+2] cycloaddition of ynones and nitrones has been developed. Very bulky ligand, DTBM-SEGPHOS, was used for an effective asymmetric induction over distal reaction centers on the linear ynone dipolarophile and for prevention of PdII catalyst deactivation by coordination of the nitrones. The reaction has wide scope of substrates in both ynones and nitrones.
Honda, Kazuya,Mikami, Koichi
supporting information
p. 2838 - 2841
(2018/09/14)
Cationic Chiral Pd-Catalyzed “Acetylenic” Diels–Alder Reaction: Computational Analysis of Reversal in Enantioselectivity
The highly enantioselective Diels–Alder reaction of acetylenic dienophiles is shown to be effectively catalyzed by cationic chiral palladium complexes. Not only the degree but also the sense of enantioselectivity critically depends on the steric demand of ligands. Computational analyses indicate that the steric demand does not affect the endo/exo-selectivity but the enantioface selectivity of dienes.