Reaction between 5-(phenoxymethyl)-2-amino-2-oxazoline and N-benzyl-3-(ethoxycarbonyl)-4-piperidinone hydrochloride:: A structural investigation

The two isomeric 7-benzyl-2-(phenoxymethyl)-2,3,6,7,8,9-hexahydro-5H [1,3]oxazolo[3,2-a] pyrido[4,3-d]pyrimidin-5-one 3 and 7-benzyl-2-(phenoxymethyl)-1,2,6,7,8,9-hexahydro-5H-[1,3]oxazolo[3,2-a]pyrido[3,4-e]pyrimidin-5-one 4 were synthesized by a one-step cyclocondensation from 5-(phenoxymethyl)2-amino-2-oxazoline 1 with N-benzyl-3-(ethoxycarbonyl)-4-piperidinone hydrochloride 2. Their structures were assigned by comparison of two dimensional NMR spectra (HMBC, NOESY) with the results obtained from theoretical calculations. The structure of one related hydrolysis compound was established using X-ray crystallography, allowing to further confirm the structure assignment. (C) 1999 Elsevier Science Ltd. All rights reserved.