Solution and Solid-Phase Synthesis of Functionalized 3-Arylbenzofurans by a Novel Cyclofragmentation - Release Pathway

A diverse family of arylbenzofurans can be generated both in solution and on solid support from a novel reaction cascade starting from 2-hydroxybenzophenones. The key step is a 5-exo-trig cyclization to generate alkoxide intermediates, which collapse to form the 3-arylbenzofuran products (see scheme), an important class of compounds in biology and medicine. Not only are electron-donating and electron-withdrawing groups tolerated in the reaction, but pyridyl, naphthyl, and sterically hindered xylene analogues can also be obtained.