Zirconium enolates, derived from copper-catalyzed asymmetric conjugate additions, are trapped with the Vilsmeier–Haack reagent. Asymmetric additions generate quaternary carbon centers with high enantioselectivity (generally ∼90% ee), and the enolates are converted to unsaturated β-chloroaldehydes (41–57% yields). The reaction tolerates changes to the nucleophile, can be used to form five-, six-, or seven-membered ring products, and is scalable to 5 mmol, and the products are readily elaborated by condensation, cross coupling, and addition reactions.

The Taxol core was prepared in five steps via a key copper-catalyzed asymmetric conjugate addition (ACA) trapping sequence. The use of a bromodiene derived alkylzirconium nucleophile followed by trapping with POCl3/DMF give a highly functionalized intermediate featuring a quaternary centre in 69% yield and 92% ee. After 1,2-addition, Suzuki-Miyaura cross coupling, allylic oxidation, and a type II intramolecular Diels-Alder reaction the taxol core was obtained in 11% overall yield with 92% ee.