Intramolecular cycloadditions of unsaturated nitrones derived from a series of N-(2-alkenyl)-2-pyrrolecarbaldehydes (2) have been systematically studied. A pronounced substituent effect has been observed as far as the competitive formation of fused- and bridged-ring regioisomers are concerned. Further elaboration of the two kinds of cycloadducts has given pyrrolizidine and indolizidine derivatives, respectively. © 2001 Elsevier Science Ltd. All rights reserved.
Broggini, G., La Rosa, C., Pilati, T., Terraneo, A., & Zecchi, G. (2001). Regiochemical aspects of intramolecular cycloadditions of nitrones derived from N-(2-alkenyl)-2-pyrrolecarbaldehydes. Competitive entries to pyrrolizidine and indolizidine derivatives. Tetrahedron, 57(39), 8323–8332. https://doi.org/10.1016/S0040-4020(01)00785-2