(E)-tert-Butyl 4-(N′-hydroxycarbamimidoyl)piperazine-1-carboxylate

In the title compound, C10H20N4O3, the piperazine ring adopts a chair conformation. The molecule adopts an E conformation across the C=N double bond, with the –OH group and the piperazine ring trans to one another. Further, the H atom of the hydroxy group is directed away from the NH2 group. An intramolecular N—H⋯O contact occurs involving the NH2 group and the oxime O atom. In the crystal, molecules are linked via strong N—H⋯O and O—H⋯N hydrogen bonds with alternating R 2 2(6) and C(9) motifs into tetrameric units forming R 4 4(28) motifs.

In the title compound, C 10 H 20 N 4 O 3 , the piperazine ring adopts a chair conformation. The molecule adopts an E conformation across the C=N double bond, with the -OH group and the piperazine ring trans to one another. Further, the H atom of the hydroxy group is directed away from the NH 2 group. An intramolecular N-HÁ Á ÁO contact occurs involving the NH 2 group and the oxime O atom. In the crystal, molecules are linked via strong N-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds with alternating R 2 2 (6) and C(9) motifs into tetrameric units forming R 4 4 (28) motifs.
Data collection: SMART (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus and XPREP (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97.  antimalarial, anticonvulsant, antipyretic, antitumor, anthelmintics, analgesic, antidepressant, antifungal, antitubercular, anticancer, antidiabetic etc. In this view, we synthesized the title compound to study its crystal structure. The molecule crystallizes in triclinic P-1 space group. The piperazine ring in the molecule adopts chair conformation and the molecule prefers E configuration across the C-N double bond, as the OH group and the piperazine ring are in the opposite side of the double bond ( Figure 1). The hydrogen atom of the hydroxyl group is directed away from the NH 2 group. This results in stabilizing the structure through a strong intermolecular O-H···N(1) and an intramolecular N(2)-H···O hydrogen bonds. In addition to this, the molecule also exhibits a strong N(2)-H···O(C) intermolecular hydrogen bond. The molecules are connected through alternate R 2 2 (6) ring and C(9) chain hydrogen bond patterns into tetrameric units exhibiting R 4 4 (28) ring patterns ( Figure 2). The average N-C bond length in the piperazine ring is 1.466 Å indicating the single bond nature. While, the N4-C(O) bond length is 1.359 (2) Å indicating the delocalization of the nitrogen lone pair of electrons into π system of the carbonyl group. The N(1)-C(1) bond length is 1.290 Å due to its double bond nature, but the N(3)-C(1) and N(2)-C(1) bond lengths are closer to N-C(O) lengths indicating the partial double bond nature of these bonds.

Experimental
To a solution of N-boc-piperazine (10.6 mmol) in 20 ml of acetonitrile was added cyanogen bromide (10.7 mmol) and K 2 CO 3 (21.2 mmol) at -10°C. The reaction mixture was stirred for 18 h at room temperature under nitrogen atmosphere.
N-Cyano-4-boc-piperazine was obtained. To N-cyano-4-boc-piperazine (4.6 mmol) in methanol was added NH 2 OH.HCl (9.3 mmol) and stirred for 30 min at room temperature. The solvent was removed under reduced pressure and the crude product was washed with cold water and dried to yield white solid product. Single crystals employed in X-ray diffraction studies were obtained from slow evaporation of the solution of the compound in methanol.

Refinement
The H atoms were positioned with idealized geometry using a riding model with C-H = 0.93 Å. All H atoms were refined with isotropic displacement parameters (set to 1.2 times of the U eq of the parent atom).

Computing details
Data collection: SMART (Bruker, 2004); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus and XPREP (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).   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 > σ(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.