Abstract
The reaction of an open-chain analogue of Reissert compound hydrofluoroborate salt with ethyl acrylate does not give a [4+2] cycloadduct as previously described, but a [3+2] cycloadduct which evolves to a 2-pyridone 15. The reaction of the title compounds leads to a [3+2] cycloadduct which evolves to a 2-pyridone.