Synthesis of 2,2‐Disubstituted 2H‐Chromenes through Carbon‐Carbon Bond Formation Utilizing a [1,2]‐Phospha‐Brook Rearrangement under Brønsted Base Catalysis.

A new methodology for the synthesis of 2,2‐disubstituted 2H‐chromenes was developed by utilizing the [1,2]‐phospha‐Brook rearrangement under Brønsted base catalysis. Phosphazene P2‐tBu efficiently catalyzed the addition reaction of 4H‐chromen‐4‐ols containing a diethoxyphosphoryl group with α,β‐unsaturated ketones, which involved the catalytic generation of a carbanion through the [1,2]‐phospha‐Brook rearrangement and subsequent conjugate addition at the 2‐position to afford adducts possessing an alkenylphosphate moiety in a highly diastereoselective manner. Further transformation of the adducts based on a nickel‐catalyzed cross‐coupling reaction with arylzinc reagents provided densely functionalized 2,2‐disubstituted 2H‐chromenes. [ABSTRACT FROM AUTHOR]