Tandem reorganisation of 1,3-dipolar cycloadducts of C-(4-oxo- 4H[1]benzopyran-3-yl)-N-phenylnitrone and allenic esters, leading to novel functionalized benzo[b]indolizines

Article abstract of DOI:10.1016/S0040-4039(98)80051-8

C-(4-oxo-4H[1]benzopyran-3-yl)-N-phenylnitrone (1) adds regiospecifically to the C₂-C₃ π-bond of allenic esters (2a-c) and the 1,3-dipolar cycloadducts formed undergo a series of intramolecular reorganisations including an intramolecular (4+2) cycloaddition, in situ, to yield novel functionalized benzo[b]indolizines (3a-c) in good yields.