Cis and trans 4,8-dimethyl-6-phenyl-5,6,7,8-tetra-hydro-4H-1,3,6-oxadiazocin-2-ones: Conformational studies and configurational assignments by NMR

The reaction of N-(2-aminopropyl)-N-(2-hydroxypropyl)aniline with phosgene afforded cis and trans isomers of 4,8-dimethyl-6-phenyl-5,6,7,8-tetrahydro-4H-1,3,6-oxadiazocin-2-one. On the basis of ASIS data and Eu-shift difference, the title compounds are found to exist as boat-chair conformation in which the carbonyl carbon resides at the BC-2 position on the molecular plane.