Chemodivergent reactions enable the selective synthesis of structurally distinct products from identical starting materials, representing a practical strategy to maximize synthetic efficiency and molecular diversity in organic synthesis. 1,3-Butadiene, one of the most abundant bulk chemicals, inherently tends to undergo Diels−Alder 4 + 2 cycloaddition with electron-deficient dienophiles. However, developing ligand-controlled chemodivergent transformations of butadiene with a less reactive substrate remains a significant challenge. Herein, we report a nickel(0)-catalyzed chemodivergent coupling of acyl imines and butadiene, where the chemoselectivity is precisely regulated by ligand manipulation. Mechanistic studies reveal that the reaction outcome is determined by the relative rates of β-H elimination and reductive elimination from a key seven-membered oxa-nickelacycle intermediate. A triaminophosphine ligand facilitates direct reductive elimination, affording kinetically controlled 2 + 4 annulated oxazine products. In contrast, a triarylphosphine ligand promotes β-H elimination, delivering thermodynamically favored hydrobivinylated dienyl amide products. This protocol features broad substrate scope and high step and atom economy and is amenable to gram-scale synthesis. Its practical utility is demonstrated by diverse postsynthetic derivatizations, as well as the applications in complex molecule synthesis. This work not only expands the synthetic toolbox for butadiene transformations but also provides a paradigm for ligand-controlled chemodivergence by exploiting the reactivity of oxa-nickelacycle species.
Liu et al. (Thu,) studied this question.