Palladium-Catalyzed, Enantioselective Formal Cycloaddition between Benzyltriflamides and Allenes: Straightforward Access to Enantioenriched Isoquinolines

Benzyl
and allyltriflamides can engage in Pd-catalyzed oxidative
(4+2) annulations with allenes, to produce highly valuable tetrahydroisoquinoline
or dihydropyridine skeletons. The reaction is especially efficient
when carried out in the presence of designed N-protected amino acids
as metal ligands. More importantly, using this type of chiral ligands,
it is possible to perform desymmetrizing, annulative C–H activations
of prochiral diarylmethylphenyl amides, and thus obtain the corresponding
isoquinolines with high enantiomeric ratios.