Versatile and regioselective synthesis of polysubstituted and highly oxygenated phenols via Dötz reaction of α-alkoxyvinyl(ethoxy)carbene complexes with alkynes

A comparative study of reactivity and selectivity of α-alkoxyvinyl(ethoxy) Fischer carbene complexes 7 and 12-13 with terminal and internal alkynes (14) in benzannulation reactions is described. The [3+2+1] cycloaddition reactions were found to be highly regioselective, favoring the formation of new and highly oxygenated tetra-, penta- and hexasubstituted phenols containing only electron-donating groups.