Five-Step Synthesis of Yaequinolones J1 and J2
J. Schwan, M. Kleoff, P. Heretsch, M. Christmann – 2020
A concise synthesis of yaequinolones J1 and J2 is reported. The route is based on the aryne insertion into the σ-C–N bond of an unsymmetric imide followed by a diastereoselective aldol cyclization of the resulting N-acylated aminobenzophenone. The chromene motif is generated in the first step by an organocatalytic tandem Knoevenagel electrocyclization of citral and 2-bromoresorcinol. The approach adheres to the ideality principle, using almost exclusively strategic bond-forming reactions.