Asymmetric Organocatalyzed Phospha‐Michael Addition for the Direct Synthesis of Biologically Active Chromenylphosphonates.

The potential of phosphites as nucleophiles for the asymmetric synthesis of chiral chromene derivatives has been overlooked in the literature. Herein, we report a promising approach via asymmetric organocatalyzed phospha‐Michael addition to iminochromenes, using a bifunctional squaramide, which gives access to chromenylphosphonates, an interesting family of bioactive compounds. Our optimized protocol provides very good reactivity, affording yields of up to 95% and with chiral products exhibiting an enantiomeric excess of up to 98%. [ABSTRACT FROM AUTHOR]