Chemodivergent Multicomponent Reactions of Morita–Baylis–Hillman-Type Yne-allylic Esters with 1,3-Dicarbonyls or Aroylacetonitriles

Herein, we introduce Morita-Baylis-Hillman-type yne-allylic esters that serve as novel precursors in a chemodivergent multicomponent reaction platform with carbon-based nucleophiles. S_<i>N</i>2″ addition of tertiary amines generates unprecedented vinyl-allenyl ammonium intermediates, whose reactivity is substrate controlled. 1,3-Dicarbonyls afford linear dienol esters via an ABC-type multicomponent reaction (MCR), while aroylacetonitriles trigger a tandem [5 + 1] annulation to give bicyclic lactols. This work provides both a new MCR for drug conjugate synthesis and an efficient route to natural product-like bicyclic lactol scaffolds.