2-Methyl-1,2,3,4-tetrahydroisoquinolin-6-yl N-phenylcarbamate

In the molecule of the title compound, C17H18N2O2, the piperidine ring adopts a half-chair form. The two benzene rings are individually planar and make a dihedral angle of 53.90°. The crystal structure is stabilized by intermolecular N—H⋯N hydrogen bonds and π–π stacking interactions (centroid–centroid distance = 3.962 Å).

In the molecule of the title compound, C 17 H 18 N 2 O 2 , the piperidine ring adopts a half-chair form. The two benzene rings are individually planar and make a dihedral angle of 53.90 . The crystal structure is stabilized by intermolecular N-HÁ Á ÁN hydrogen bonds andstacking interactions (centroid-centroid distance = 3.962 Å ).

Comment
In the molecular structure of title compound (Fig.1), the piperidine ring adopts a half-chair form, with atoms N2 and C9 out of the plane defined by the remaining four atoms. The N1-C1 bond length [1.3485 (19) Å] is longer than that (1.32 Å) for a peptide linkage. The N1-C11 bond length [1.4128 (19) Å] is shorter than a normal C-N single bond and longer than a normal C═N bond, probably as a result of electron delocalization, suggesting that the N1-C11 bond participates in the conjugated system of the benzene ring (Li et al., 2006). The two phenyl rings are planar and make a dihedral angle of 53.90°. The crystal structure is stabilized through intermolecular N1-H1···N2 i hydrogen bonds [symmetry code (i): 1-x, 1-y,, 1-z] and π-π stacking interactions (Fig.2).

Experimental
The 2-methyl-1,2,3,4-tetrahydroisoquinolin-6-ol (6.13 mmol) was dissolved in anhydrous THF (100 ml), and a piece of Na metal (approximately 10 mg) was added. The mixture was stirred at room temperature for 15 min, then phenylisocyanate (18.48 mmol) was added. The reaction mixture was continuously stirred for 2 h at room temperature and monitored by TLC.
The precipitate was filtered off and the filtrate was evaporated to give yellow oil. The 20 ml H 2 O was added and pH of the aqueous layer was adjusted to 3 by 1 N HCl, washed with Et 2 O, and then pH was adjusted to 10 by NaHCO 3 aqueous solution (approximately 1%). The resulting precipitate was filtered and washed with water three times. A yellow solid (yield 1.50 g, 87%) was obtained, and single crystals suitable for crystallographic analysis were obtained by slow evaporation of an ethanol solution.

Refinement
All C-bound H atoms were positioned geometrically and refined as riding (C-H = 0.93-0.97 Å), with U iso (H) = 1.2U eq (C) and the three H atoms of the methyl refined as riding (C-H = 0.98 Å), with U iso (H) = 1.5U eq (C). The H atom of the NH group was refined isotropically.

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 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.