Concise and Stereodivergent Approach to Chromanone Lactones through Copper‐Catalyzed Asymmetric Vinylogous Addition of Siloxyfurans to 2‐Ester‐Substituted Chromones.

Vicinal oxygen‐containing tetra‐ and tri‐substituted stereocenters exist widely in chromanone lactone and tetrahydroxanthone natural products. Their enantioselective construction in a single step remains elusive and poses a formidable challenge for chemical synthesis. Here, we report the first copper(I)‐catalyzed asymmetric vinylogous additions of siloxyfurans to 2‐ester‐substituted chromones, which enable concise and enantioselective assembly of chromanone lactones. Both syn and anti adducts can be accessed with excellent diastereo‐ and enantioselectivity by judicious choice of the chiral ligands. Our approach allowed for the efficient synthesis of (−)‐blennolide B with precise stereochemical control, which provides a formal synthesis of secalonic acid A. [ABSTRACT FROM AUTHOR]