Stereoselective transformation of 2H-1,4-oxazin-2-ones into 2,(2),5,5-tri-and tetrasubstituted analogues of cis-5-hydroxy-2-piperidinemethanol and cis-5-hydroxy-6-oxo-2-piperidinecarboxyl acid

2,(2),5,5-Tri- and tetrasubstituted analogues of 5-hydroxy-2-piperidinemeth anol and 5-hydroxy-6-oxo-2-piperidinecarboxylic acid have been prepared via Diels-Alder reaction of 3-substituted 2H-1,4-oxazin-2-ones with ethene fol lowed by functional group transformation of the resulting imidoyl chloride and lactone groups. Some of the 2-piperidinemethanol products are converted further into potential substance P antagonists. (C) 2000 Elsevier Science Ltd. All rights reserved.