EFFICIENT SYNTHESIS OF INDOLES AND BENZO[b]FURANS VIA [3,3]-SIGMATROPIC REARRANGEMENT OF N-TRIFLUOROACETYL ENEHYDRAZINES AND ENEHYDROXYLAMINES

This review summarizes an efficient synthesis of benzo[b]furans and indoles via [3,3]-sigmatropic rearrangements of N-trifluoroacetyl enehydroxylamines and enehydrazines, which were triggered by acylation of oxime ethers and hydrazines. TFAA and TFAT-DMAP have been proved to be the best reagent to induce [3,3]-sigmatropic rearrangement for the synthesis of benzo[b]furans and indoles. This method was successfully applied to the short synthesis of natural products.