STEREOSTRUCTURE OF A NORBORNANE DIEXO-CONDENSED 1,3-OXAZINE[2,3-A]ISOINDOLONE - AN X-RAY STUDY

The structure of -octahydro-2H-3,1-benzoxazino[2,3-a]isoindol-8-one (C 23H23NO2, M(r) = 345.42), prepared from 2-p-toluoylbenzoic acid and di exo-3-hydroxymethylbicyclo [2.2.1]heptyl-2-amine, has been established by X-ray crystallography from diffractometer data: it crystallizes in the triclinic space group P ($) over bar 1 with a = 8.186(2) Angstrom , b = 8.683(2) Angstrom, c = 13.324(5) Angstrom, alpha = 83.46(4)degre es, beta = 75.48(6)degrees, gamma = 77.60(4)degrees, V = 893.6(4)Angst rom(3), Z = 2, D-c = 1.284 g cm(-3) and mu(CuK alpha) = 0.641 mm(-1). The structure was solved by direct methods and refined to R = 0.061 fo r 3685 observed reflections. The molecule exhibits diexo-annelation be tween the 1,3-oxazine ring and the norbornane moiety. The p-tolyl grou p and norbornane annelation hydrogens are trans and the 1,3-oxazine ri ng is fused to an almost planar gamma-lactam ring. Consequently, the s ix-membered hetero ring assumes an irregular conformation among the ca nonical forms S-1(6), T-1(3) and B-3,B-6.