1,10,10-Trimethyl-5-phenyl-3-oxa-4-azatricyclo[5.2.1.02,6]dec-4-en-2-ol

The title compound, C17H21NO2, was synthesized by the reaction of (1R)-(+)-3-benzylcamphor and hydroxylamine. The oxazole ring makes a dihedral angle of 23.42 (16)° with the phenyl ring. The six-membered ring of the norboryl group adopts a boat conformation, whereas each of the five-membered rings of the norboryl group displays a flattened envelope conformation, with the C atom carrying the methyl groups representing the flap for both rings. In the crystal, molecules are linked into zigzag chains propagating along the b axis by O—H⋯N hydrogen bonds.

The title compound, C 17 H 21 NO 2 , was synthesized by the reaction of (1R)-(+)-3-benzylcamphor and hydroxylamine. The oxazole ring makes a dihedral angle of 23.42 (16) with the phenyl ring. The six-membered ring of the norboryl group adopts a boat conformation, whereas each of the fivemembered rings of the norboryl group displays a flattened envelope conformation, with the C atom carrying the methyl groups representing the flap for both rings. In the crystal, molecules are linked into zigzag chains propagating along the b axis by O-HÁ Á ÁN hydrogen bonds.   Table 1 Hydrogen-bond geometry (Å , ).

Comment
The versatility and importance of camphor as a chiral starting material in the synthesis of natural products is primarily due to the availability of methods for the introduction of functional groups (Jennings & Herschbach, 1965;Pastrán et al., 2011). We have developed a series of complexes based on camphor 1,3-diketonato ligands (Spannenberg et al., 2002;Harrad et al., 2010;Ait Ali et al., 2006), and their application in catalytic asymmetric reactions has been described (Gaudo et al., 2011). In this work, we present the structure of a new heterocyclic compound (1,10,10-trimethyl-5phenyl-3-oxa-4-aza-tricyclo[5.2.1.02,6]dec-4-en-2-ol)) which we have synthesized by hetercyclization from benzylcamphor with hydroxylamine. In the molecule (Fig. 1), the six-membered ring of the norboryl system adopts a boat  (Table 1).

Experimental
(1R)-(+)-3-benzyl-camphor (1 mmol), and hydroxylamine (2 mmol), in dichloromethane (10 ml) were vigorously stirred at reflux. The progress of the reaction was followed by TLC. The reaction went to completion after 24 h. After completion of the reaction, the mixture was diluted with H 2 O (10 ml) and extracted with EtOAc (2 × 10 ml) and dried over Na 2 SO 4 . The title compound was isolated as a white powder by column chromatography on silica gel using ethyl acetate-n-hexane as eluant (yield 79%; m.p. = 145°C). Colourless single crystals suitable for X-ray analysis were obtained by slow evaporation of n-hexane solution.

Refinement
All H atoms were fixed geometrically and treated as riding with O-H = 0.82 Å, C-H = 0.96 Å (methyl), 0.97 Å (methylene), 0.98 Å (methine) with U iso (H) = 1.2U eq (methylene, methine) or U iso (H) = 1.5U eq (methyl). The torsion angle about the C-O bond of the hydroxyl group was refined. In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and thus Friedel pairs were merged and any references to the Flack parameter were removed.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.