Syntheses of 2‐Benzylbenzofuran Derivatives and 2‐Aryl‐nitrochroman Derivatives from Nitroalkene Precursors

Simple and straightforward methods for the synthesis of 2‐benzylbenzofuran, 3‐substituted 2‐benzylbenzofuran, and 2‐aryl‐nitrochroman derivatives are described. Benzofurans were generated from nitroalkenes by reduction with NaBH 4 followed by a Nef reaction and acid‐mediated cyclization, whereas 3‐substituted 2‐benzylbenzofurans were prepared from nitroalkenes by reactions with Grignard reagents followed by a Nef reaction and an acid‐mediated cyclization in a one‐pot process. The synthesis of chromans involved a Knoevenagel condensation and the 1,4‐diazabicyclo[2.2.2]octane (DABCO) assisted cyclization of β‐(2‐hydroxyphenyl)‐nitroethanes and benzaldehydes, also in a one‐pot process.