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.

苄基（Benzyl）与烯丙基三氟酰胺（allyltriflamides）可与丙二烯（allenes）发生钯催化的氧化(4+2)环化反应，生成极具应用价值的四氢异喹啉（tetrahydroisoquinoline）或二氢吡啶（dihydropyridine）骨架。当以经设计合成的N-保护氨基酸作为金属配体（metal ligands）时，该反应的催化效率尤为优异。更为关键的是，采用这类手性配体（chiral ligands），可实现前手性二芳基甲基苯基酰胺的去对称化环化型C-H活化反应，从而获得对应高对映体比例（enantiomeric ratios）的异喹啉产物。