Stereoselective transformation of pyrazinones into substituted analogues of cis-5-amino-6-oxo-2-piperidinemethanol and cis-5-amino-2-piperidinemethanol

Various analogues of cis-5-amino-6-oxo-2-piperidinemethanol and cis-5-amino-2-piperidinemethanol have been prepared via Diels–Alder reaction of substituted pyrazinones with ethene followed by acid methanolysis of the bridged lactam adducts. Further reduction of the resulting methyl 2-piperidinecarboxylate ester compounds led to the corresponding 2-piperidinemethanol products that were converted into potential SP antagonists.