2-Methyl-4-phenyl-3,4-dihydroquinazoline

The title compound, C15H14N2, was formed during the lithiation of 2-methylquinazoline with phenyllithium followed by hydrolysis of the intermediate lithium 2-methyl-4-phenyl-4H-quinazolin-3-ide. NMR spectra as well as single-crystal X-ray structural data indicate that the reaction product to have the same structure in chloroform solution as in the crystalline state. The phenyl substituent is twisted out of the plane of the 3,4-dihydroquinazoline ring system by 86.47 (7)°. In the crystal, intermolecular N—H⋯N interactions connect the molecules into infinite chains.

The title compound, C 15 H 14 N 2 , was formed during the lithiation of 2-methylquinazoline with phenyllithium followed by hydrolysis of the intermediate lithium 2-methyl-4-phenyl-4H-quinazolin-3-ide. NMR spectra as well as single-crystal X-ray structural data indicate that the reaction product to have the same structure in chloroform solution as in the crystalline state. The phenyl substituent is twisted out of the plane of the 3,4-dihydroquinazoline ring system by 86.47 (7) . In the crystal, intermolecular N-HÁ Á ÁN interactions connect the molecules into infinite chains.
Academy Professor Kari Rissanen and the Academy of Finland (project No. 212588 for KR) are gratefully acknowledged for funding. Dr Katri Laihia is thanked for characterization of the NMR spectra.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IM2274).
In crystalline state the title compound shows the 3,4-dihydroquinazoline moiety to be planar (Fig. 1). The phenyl substituent is twisted out of plane of the moiety by 86.47 (7) °, which is rather close to the twist (79.3 (1) °) found in 2-methyl-4-phenyl-3,4-dihydroquinazolinium chloride (Rajnikant et al., 2002). Intermolecular N3-H···N1 hydrogen bonds (-y, x-y + 1, z + 1/3 direction) define the supramolecular structure and connect the molecules to infinite helical chains (Fig. 2). Unfortunately, no reliable determination of the absolute structure (or handedness of helix) is possible by X-ray crystallography. Suitable single crystals for X-ray diffraction were obtained by very slow evaporation of analytical sample from NMRtube, where CDCl 3 was used as a solvent.

Refinement
In the absence of significant anomalous disperson effects, Friedel pairs were averaged. All H atoms were visible in electron density maps, but were calculated at their idealized positions and allowed to ride on their parent atoms at C-H distances of 0.95 Å (aromatic), 0.98 Å (methyl), 1.00 Å (methine), and N-H distance of 0.88 Å, with U iso (H) of 1.2 times U eq (C,N) or 1.5 times U eq (C) (methyl).