Nitrones and Oxaziridines. LXVII. Intermolecular Cycloaddition of Fused Indolyl Nitrone Ring Systems

Abstract

The two dihydro-β-carboline N-oxides (6) and (18) have been prepared by reductive cyclization of 2-acetyl-3-(β- nitroethyl ) indoles. These cyclic nitrones undergo 1,3-dipolar cycloaddition to alkynes to give the cycloadducts (21)-(25). Thermal rearrangement of the adduct (22) gives the indolizino [8,7-b] indole (27) in high yield. The X-ray crystal structure determination of the adduct (24) is reported.