3,6-dihydropyridines from 6-endo radical cyclisation onto nitrogen in β-allenyl ketoximebenzoates

Article abstract of DOI:10.1016/S0040-4039(99)00806-0

When tosyl bromide is added under free radical conditions to β-allenyl- 1-phenylketoximebenzoates, a carbon-centred radical resulting from the addition of the tosyl radical on the sp carbon is formed. Depending on the substitution pattern of the allenyl moiety, this carbon-centred radical traps a bromine atom or undergoes a rare 6-endo cyclisation onto the nitrogen atom leading to 3,6-dihydropyridines in good yields.