Ethyl 2-[(Z)-2-benzylhydrazin-1-ylidene]-2-bromoacetate

In the title compound, C11H13BrN2O2, the dihedral angle between the phenyl ring and the almost planar (r.m.s. deviation = 0.011 Å) C—C(Br)=N—N(H)— fragment is 74.94 (16)°. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, which generate C(6) chains propagating in [010]. Weak aromatic π–π stacking [centroid–centroid separation = 3.784 (3) Å] may also help to consolidate the packing.


Related literature
For the use of the title compound in the preparation of heterocyclic compounds via the diploar cycloaddition of thiadiazole, see Feddouli et al. (2004); Abouricha et al. (2005); Hafez et al. (2008). For the synthesis of the title compound, see Bach et al. (1994).

Structure Reports Online
The crystal structure of the title compound is given in Fig. 1. In the crystal, the adjacent molecules are stabilized by N-H···O hydrogen bonding, with the distance of 2.965 (4) Å (Table 1). Molecules are linked into chain along the b axis by the above hydrogen bond (Fig. 2).

Experimental
To a stirred solution of ethyl 2,2-diethoxyacetate (1 ml, 5.6 mmol) and acetyl chloride (0.8 ml, 11.2 mmol) was added iodine (3 mg, 0.01 mmol). After the mixture was stirred for overnight, excess acetyl chloride was removed in vacuo, the residue in 1,4-dioxane (25 ml) was treated with benzylhydrazine dihydrochloride (1.09 g, 5.6 mmol) in water (10 ml), then the mixture was adjusted to pH 4. After 1 h the mixture was neutralized to pH 8 with saturated NaOH and evaporated in vacuo. The residue was added water and extracted with CH2Cl2, the organic layer was dried over MgSO4, filtered and concentrated. The crude compound was dissolved in AcOEt (8 ml), which was reacted with NBS (1.1 g, 6.2 mmol) for 2 h.
After evaporation of the solvent, the residue was dissolved in CH2Cl2 and filtered, the filtrate was concentrated and purified by column chromatography (eluent: PE/AcOEt = 28/1) to give the title compound (0.67 g, 2.35 mmol) as a white solid.
Colorless blocks of (I) were grown in PE/AcOEt (14/0.5, V/V) solution by slow evaporation at room temperature.