3-Bromo-5-methoxy-4-(4-methylpiperidin-1-yl)furan-2(5H)-one

There are two molecules in the asymmetric unit of title compound, C11H16BrNO3, which was obtained via the tandem Michael addition–elimination reaction of 3,4-dibromo-5-methoxyfuran-2(5H)-one and 4-methylpiperidine in the presence of potassium fluoride. The furanone rings are approximately planar [maximum atomic deviations of 0.026 (2) and 0.015 (2) Å, respectively]. The packing is stabilized by weak intermolecular C—H⋯O and C—H⋯Br interactions.

There are two molecules in the asymmetric unit of title compound, C 11 H 16 BrNO 3 , which was obtained via the tandem Michael addition-elimination reaction of 3,4-dibromo-5methoxyfuran-2(5H)-one and 4-methylpiperidine in the presence of potassium fluoride. The furanone rings are approximately planar [maximum atomic deviations of 0.026 (2) and 0.015 (2) Å , respectively]. The packing is stabilized by weak intermolecular C-HÁ Á ÁO and C-HÁ Á ÁBr interactions.
Attracted by versatile 4-amino-2(5H)-furanones, we synthesized the title compound with 3,4-dibromo-5-methoxyfuran-2(5H)-one and 4-methylpiperidine in the presence of potassium fluoride via the tandem Michael addition-elimination reaction. Due to the presence of the 2(5H)-furanone moiety and polyfunctional groups (carboxyl, amino, halo) the title compound is expected to be a biologically active product and excellent ligand.
In the title compound, (I), two crystallographically independent molecules with R and S spatial configurations are present in the asymmetric unit. The furanone ring is approximately planar, similar to that found in a related compound (Song, Li et al. 2009). Additionally, the molecules are linked by weak C-H···O and C-H···Br intermolecular interactions.

Experimental
The precursor 3,4-dibromo-5-methoxyfuran-2(5H)-furanone was prepared according to the literature procedure (Song, Wang et al., 2009). After the mixture of 3,4-dibromo-5-methoxyfuran-2(5H)-furanone (2.0 mmol) and potassium fluoride (6.0 mmol) was dissolved in absolute tetrahydrofuran (2.0 mL) under nitrogen atmosphere, a tetrahydrofuran solution of 4-methylpiperidine (2.0 mmol) was added. The reaction was carried out under stirring at room temperature for 48 h. Once the reaction was complete, the solvents were removed under reduced pressure. The residual solid was dissolved in dichloromethane and extracted. The combined organic layers from the extraction were concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography with a gradient mixture of petroleum ether and ethyl acetate to give the product yielding (I) 0.2988 g (51.7%).

Refinement
H atoms were positioned in calculated positions with C-H = 0.93-0.98 Å and were refined using a riding model, with U iso (H) = 1.5U eq (C) for methyl and 1.2U eq (C) for the others.  3-Bromo-5-methoxy-4-(4-methylpiperidin-1-yl)furan-2(5H)-one Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.