2,4-Di-tert-butyl-6-({[(R)-1-phenylethyl]amino}methyl)phenol

Abstract

There are two molecules in the asymmetric unit of the title compound, C 23 H 33 NO, in which the dihedral angles between the aromatic rings are 72.1 (3) and 89.0 (2) . One of the molecules features a tert-butyl group disordered over two sets of sites in a 0.545 (13):0.455 (13) ratio. Both molecules feature an intramolecular O-HÁ Á ÁN hydrogen bond, which closes an S(6) ring. Neither of the N-H groups participates in hydrogen bonds, perhaps due to steric crowding. Structure descriptionInterest in the title compound arises from the highly catalytic activity of phenoxy-imine ligated group IV metal complexes (now known FI catalysts) for olefin polymerization (Fujita et al., 2014; Makio et al., 2011). The structure of the title compound (phenoxyamine) is similar to phenoxy-imine ligands of FI catalysts, but phenoxy-amines are considered to be conformationally more flexible to chelate metal ions as they are not constrained to be planar (Sreenivasulu & Vittal, 2003; Yang et al., 2003). Moreover, group IV metal complexes bearing phenoxy-amine ligands have exhibited highly catalytic activities for the polymerization of olefins (Alesso et al., 2011; Wan et al., 2013). As a part of our studies in this area, we have prepared the title compound ( Fig. 1) and determined its crystal structure.There are two molecules in the asymmetric unit, in which the dihedral angles between the aromatic rings are 72.1 (3) for the C1 molecule and 89.0 (2) for the C24 molecule. Both molecules feature an intramolecular O-HÁ Á ÁN hydrogen bond (Fig. 2, Table 1), which closes an S(6) ring. Neither of the N-H groups participate in hydrogen bonds, perhaps due to steric crowding. Synthesis and crystallizationA solution of (R)--phenylethylamine (1.21 g, 10 mmol) and 3,5-di-tert-butylsalicylaldehyde (2.34 g, 10 mmol) in 15 ml of ethanol was stirred for 12 h at 25 C, and then the resulting precipitate was collected to give the corresponding iminophenol. A suspension of above obtained iminophenol in 20 ml of ethanol was cooled to 0 C, and NaBH 4 (0.57 g, 15 mmol) was added portionwise with stirring at 0 C over a period of 30 min. After the reaction mixture was stirred 12 h at 25 C, the solvents were removed under reduced pressure and the residue was dissolved in 20 ml H 2 O and then extracted with CH 2 Cl 2 . The organic layer was washed with brine and dried over Na 2 SO 4 , and the solvents were removed under reduced pressure and the residue was recrystallized from ethanol solution to give the title compound (2.40 g, 70.6% yield) as white needle-like crystals. 1 136.6, 129.4, 128.2, 127.2, 124.1, 123.6, 122.9, 58.1, 51.9, 35.6, 34.8, 32.4, 30.3, 24.0. Elemental analysis (calcd %) for C 23 H 33 NO: C, 81.37; H, 9.80; N, 4.13. Found: C, 81.25; H, 9.77; N, 4.12.The title compound (20 mg) was dissolved in dichloromethane (2 ml). The solution was allowed to evaporate slowly over several days to yield colorless blocks. RefinementCrystal data, data collection and structure refinement details are summarized in Table 2. One of the tert-butyl groups in the...