4<i>H</i>‐1‐Benzopyrans by a tandem S_N2‐S_NAr reaction

Abstract

Abstract magnified image Treatment of 2‐fluoro‐5‐nitrobenzyl bromide with active methylene compounds in the presence of excess potassium carbonate in acetone leads to the formation of highly functionalized 4 H ‐1‐benzopyrans by a tandem S N 2‐S N Ar reaction sequence. The reaction works well with β‐keto esters, β‐keto sulfones, β‐keto phosphine oxides, β‐keto phosphonates and β‐keto nitriles. The reaction is simple to perform and affords products in 50‐92% yields.