Rhodium Catalyzed Synthesis of Benzopyrans via Transannulation of <i>N</i>‑Sulfonyl-1,2,3-triazoles with 2‑Hydroxybenzyl Alcohols

An efficient and novel rhodium-catalyzed transannulation of <i>N</i>-sulfonyl-1,2,3-triazoles with in situ generated <i>o</i>-quinone methides (<i>o</i>-QMs) from 2-hydroxybenzyl alcohols has been achieved for the synthesis of substituted benzopyrans in good yields. The developed reaction involves nucleophilic attack of <i>o</i>-QM to α-imino rhodium carbenoid to generate a carbonyl ylide followed by 6π-electrocyclization and isomerization. Furthermore, the utility of the methodology was demonstrated in the one-pot synthesis and construction of polyheteroaromatics