2-Hydroxy-3,3-dimethyl-7-nitro-3,4-dihydroisoquinolin-1(2H)-one

In the title compound, C11H12N2O4, a new hydroxamic acid which belonging to the isoquinole family, the heterocyclic ring adopts a half-chair conformation. The nitro group is essentially coplanar with the aromatic ring. Intermolecular O—H⋯O hydrogen bonds assemble the molecules around inversion centres to form pseudo-dimers.

In the title compound, C 11 H 12 N 2 O 4 , a new hydroxamic acid which belonging to the isoquinole family, the heterocyclic ring adopts a half-chair conformation. The nitro group is essentially coplanar with the aromatic ring. Intermolecular O-HÁ Á ÁO hydrogen bonds assemble the molecules around inversion centres to form pseudo-dimers.
The growing number of published synthetic methods further points to the biological significance of hydroxamic acids (Porcheddu & Giacomelli, 2006). Among this family of hydroxamic acids is the title compound (1). We report herein its synthesis and its crystal structure determination. Synthesis of the title compound has been prepared from the corresponding dihydroisoquinoleine (2) by metachloroperbenzoic acid oxidation (Fig. 1). Imine (2) was described by Bohé and Kammoun (2004), in three steps from the commercially available tertiary alcohol (3).
In the title compound, the heterocyclic ring adopts a half-chair conformation as indicated by the puckering parameters: , 1975). The nitro group attached on C7 is essentially coplanar with the aromatic nucleus (Fig. 2). The methyl substituent in position 3 of the heterocyclic ring is pseudo-axial, the second methyl in position 3 is pseudo-equatorial.
The conformation of (1) is stabilized by an intramolecular hydrogen bond between the hydroxyl O12-H12 group and atom O11 (Table 1).The molecules are assembled by intermolecualr O-H···O hydrogen bonds to form pseudo dimer arranged around inversion centre (Table 1, Fig. 3)

Experimental
The title compound was prepared by reaction of imine (2) (100 mg, 0.49 mmol), and methachloroperbenzoique acid 86% (197 mg, 0.98 mmol) in dichloromethane (15 ml). The mixture was stirred at room temperature for 24 h. Then, the mixture was diluted with CH 2 Cl 2 and washed with a solution of saturated NaHCO 3 . The organic phase was dried over sodium sulfate, filtered and concentrated under reduced pressure.

Special details
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 > σ(F 2 ) is used only for calculating Rfactors(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.