2-tert-Butyl-4-chloro-5-[4-(2-fluoroethoxy)benzyloxy]pyridazin-3(2H)-one

In the title compound, C17H20ClFN2O3, the dihedral angle between the pyridazine and benzene rings is 41.37 (10)°. In the crystal, there are no significant intermolecular interactions present. The terminal –CH2F group is disordered over two sets of sites with an occupancy ratio of 0.737 (2):0.263 (2).


Related literature
The molecular structure of the title compound (measured at 150 K) is shown in Fig. 1. The dihedral angle between the pyridazine ring and the benzene ring is 41.37 (10)°. The terminal CH 2 F group is disordered between two positions with occupancies 0.737 (2) for C1F1 and 0.263 (2) for C1AF1A.

Experimental
The synthesis route is shown in Fig. 2. The solution of tert-butylammonium fluoride (1 mmol in 1 ml tetrahydrofuran) was stirred in a stream of nitrogen at 110 °C to remove the solvent. Then 2-tert-butyl-4-chloro-5-(4-(2-tosylethoxy-ethoxy)-benzyloxy)-2H-pyridazin-3-one (compound I, 0.30 mmol in 3 ml anhydrous CH 3 CN) was added to the above evaporation residue, and refluxed for 40 min at 90 °C. After concentration under reduced pressure, the residue was chromatographed over a column of silica gel and eluted with the mixture of dichloromethane and methanol (100:1). The product was obtained as white solid. The product was then recrystallized from the mixture of hexane and methanol (2:1) yielding colorless crystals of the title compound suitable for the single-crystal X-ray diffraction.

Refinement
The H atoms bound to C atoms were positioned geometrically and refined using a riding model, with C-H = 0.99 Å for CH 2 groups, 0.95 Å for aryl and 0.98 Å for methyl H atoms, U iso (H) =1.2U eq (C) for CH 2 groups and aryl, and U iso (H) =1.5U eq (C) for methyl H atoms.

Figure 2
The synthesis route of the title compound. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.32 e Å −3 Δρ min = −0.28 e Å −3 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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (