Ni-Catalyzed Ligand-Controlled Regiodivergent Reductive Dicarbofunctionalization of Alkenes

Transition-metal-catalyzed dicarbofunctionalization of alkenes involving intramolecular Heck cyclization followed by intermolecular cross-coupling has emerged as a powerful engine for building heterocycles with sterically congested quaternary carbon centers. However, only exo-cyclization/cross-coupling products can be obtained; endo-selective cyclization/cross-coupling has not been reported yet and still poses a formidable challenge. We herein report the first example of catalyst-controlled dicarbofunctionalization of alkenes for the regiodivergent synthesis of five- and six-membered benzo-fused lactams bearing all-carbon quaternary centers. Using a chiral Pyrox- or Phox-type bidentate ligand, 5-exo cyclization/cross-couplings proceed favorably to produce indole-2-ones in good yields with excellent regioselectivity and enantioselectivities (up to 98% ee). When C6-carboxylic acid-modified 2,2'-bipyridine was used as the ligand, 3,4-dihydroquinolin-2-ones were obtained in good yields through 6-endo-selective cyclization/cross-coupling processes. This transformation is modular and tolerant of a variety of functional groups. The ligand rather than the substrate structures precisely dictates the regioselectivity pattern. Moreover, the synthetic value of this regiodivergent protocol was demonstrated by the preparation of biologically relevant molecules and structural scaffolds.

Automated summary

This study presents a catalyst-controlled dicarbofunctionalization of alkenes for the synthesis of five- and six-membered benzo-fused lactams bearing all-carbon quaternary centers. Different regioselectivity patterns can be achieved by using chiral bidentate ligands, resulting in high yields and excellent enantioselectivities. The synthetic value of this regiodivergent protocol is demonstrated by the preparation of biologically relevant molecules and structural scaffolds.