W0086

Crystal Structure of 4,8a-dimethyl-2-phenyl-4a,5,6,7,8,8a-hexahydro-4H-benzo[d] [1,3]oxazine Exhibiting Two Types of Enantiomeric Disorder. Hemant Yennawar^a, Jacob Waldman^b, Wenchun Chao^b, Charles Campana^c, Steven Weinreb^b, ^aDept. of Biochemistry and Molecular Biology, ^bDept. of Chemistry, The Pennsylvania State Univ., University Park PA 16802, ^cBruker AXS, Inc., 5465 East Cheryl Parkway, Madison, WI 53711, hpy1@psu.edu.

A racemic mixture of 4,8a-dimethyl-2-phenyl-4a,5,6,7,8,8a-hexahydro-4H-benzo[d] [1,3]oxazine, C₁₆H₂₁NO has been crystallized in P-1 space group. The structure has been determined and refined to an R=0.052. The asymmetric unit contains four molecular sites for the oxazine. Two of the four sites have enantiomeric disorder, each a different type.

The first enantiomeric pair (E, F) has a mirror plane running between the molecules. The second pair (C, D) has a perfect two-fold rotation axis down the C-C bond connecting phenyl ring with the oxazine moiety. The oxygen and the nitrogen atoms switch positions, leaving the phenyl group exactly in the same position.