Crystal structure of 5-chloromethyl-N-methyl-4-[(4-phenyl-1,2,3-triazol-1-yl)methyl]isoxazolidine-3-carboxamide

The title compound crystallized with two independent molecules in the asymmetric unit. Each molecule has three stereogenic centres with configurations 2(S), 3(S) and 4(R), confirmed by resonant scattering.

The conformations of the two molecules differ significantly, as seen in the overlay fit of the two molecules (Fig. 2). In molecule A the phenyl ring is inclined to the triazole ring by 32.5 (2) , while in molecule B the corresponding dihedral angle is 10.7 (2) . The torsion angle C6-C7-C8-C13 is 31.5 (5) in molecule A, while torsion angle C21-C22-C23-C24, is À9.0 (5) in molecule B. The isoxazolidine rings (O1/ N1/C2-C4 in molecule A and O3/N6/C17-C19 in molecule B) adopt envelope conformations. In molecule A atom O1 is displaced by 0.566 (2) Å from the mean plane through atoms N1/C2-C4, while in molecule B atom O3 is displaced by 0.528 (2) Å from the mean plane through atoms N6/C17-C19. Their mean planes are inclined to the relevant triazole ring by 53.95 (19) in molecule A and by 62.32 (18) in molecule B.

Supramolecular features
In the crystal of (2), the two independent molecules are linked via an N-HÁ Á ÁO and a C-HÁ Á ÁO hydrogen bond (Table 1 and Fig. 3). These units are then linked via C-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds, forming slabs lying parallel to the ab plane (Table 1 and Fig. 3). Within the slabs there are C-HÁ Á Á interactions present involving symmetry-related A molecules (Table 1) Table 1 Hydrogen-bond geometry (Å , ).

Figure 3
A view along the c axis of the crystal packing of compound (2). Hydrogen bonds are shown as dashed lines (see Table 1) and H atoms not involved in these interactions have been omitted for clarity.

Figure 1
The molecular structure of the two independent molecules of compound (2), showing the atom labelling. Displacement ellipsoids are drawn at the 30% probability level. C-bound H atoms have been omitted for clarity.

Spectroscopic investigations
The spectroscopic measurements are consistent with the crystal structure of (2