Rhodium(I)-complexes catalyzed 1,4-conjugate addition of arylzinc chlorides to N-boc-4-pyridone

Abstract

Rhodium(I)-complexes catalyzed the 1,4-conjugate addition of arylzinc chlorides to N-Boc-4-pyridone in the presence of chlorotrimethylsilane (TMSCl). A combination of [RhCl(C2H4)2]2 and BINAP was determined to be the most effective catalyst to promote the 1,4-conjugate addition reactions of arylzinc chlorides to N-Boc-4-pyridone. A broad scope of arylzinc reagents with both electron-withdrawing and electron-donating substituents on the aromatic ring successfully underwent 1,4-conjugate addition to N-Boc-4-pyridone to afford versatile 1,4-adducts 2-substituted- 2,3-dihydropyridones in good to excellent yields (up to 91%) and excellent ee (up to 96%) when (S)-BINAP was used as chiral ligand.