Crystal structure of (+)-(R)-3-methyl-1-(1'-phenyl-ethyl)-1H-pyridin-2-one.

wide interest because the 1H-pyridin-2-ones obtained in this process are versatile synthetic building blocks in the synthesis of alkaloids,1–5 although little has been done concerning their use in asymmetric synthesis. This contrasts with the large use of chiral piperidones, which have recently been reported. The synthetic method proceeds first through the addition of the hydroxide anion at position 2 of the pyridinium ring, giving a pseudobase, which is further oxidized by potassium ferricyanide. The title compound, (+)-(R)-3-methyl-1-(1′-phenyl-ethyl)-1Hpyridin-2-one II, was prepared by stirring a solution of pyridinium salt, I (4.0 mmol), in water (25 ml) and cooled to 5 ̊C (Scheme 1). A solution of K3Fe(CN)6 (11 eq.) in water (30 ml) was added dropwise over a period of 1 h. Then, a solution of KOH (15.8 eq.) in water (6 ml) was added dropwise over 30 min. Toluene (40 ml) was added and the mixture warmed at 40 ̊C for 30 min. The organic layer was extracted with dichloromethane (4 × 50 ml). The combined organic layers were dried over Na2SO4 and the solvent was removed in vacuo. The residue was purified by column chromatography (SiO2), eluting with dichloromethane and dichloromethane/methanol 98:2. Compound II was recrystallized from dichloromethane/diethylether solution; m.p. 128 – 130 ̊C; [α]D + 27.61 (c, 1.0, CH2Cl2); IR(KBr): 3073 – 3032, 2979, 1646, 1588, 1546, 761 cm–1. 1H NMR: δ (ppm, CDCl3, J Hz): 7.36 – 7.28 (m, 5H, Φ); 7.25 (d, 1H-4, 6.24); 7.08 (d, 1H-6, 6.96); 6.42 (q, 1H1′, 7.32); 6.14 (t, 1H-5, 6.24); 2.14 (s, 3H-7); 1.68 (d, 3H-2′, 7.32). The structure solution was studied to verify the chemical structure. Intensity data for the crystals of the title compound were collected by graphite-monochromatized Mo Kα radiation at 293 K, and were corrected for Lorentz and polarization effects. No absorption correction was applied. The compound is sufficiently stable, and no change in the crystalline appearance was observed during X-ray exposure. The structure was solved by direct methods and refined by full-matrix least-squares with anisotropic temperature factors for the non-hydrogen atoms. All H atoms were located on difference Fourier maps. Their positions and isotropic displacement parameters were refined in the final least-squares cycles of refinement. The software used to prepare the material for publication was PARST97.6 Table 1 summarizes the crystal and experimental data. The molecular structure of the title compound is shown in Fig.1. 1247 ANALYTICAL SCIENCES OCTOBER 2001, VOL. 17 2001 © The Japan Society for Analytical Chemistry