Experimental. Crystal data. C 10 H 12 N 6 C 2 H 6 O M r = Monoclinic, C2=c a = (19) Å b = (2) Å c = (3) Å = 101.

Transcription

1 organic compounds Acta Crystallographica Section E Structure Reports Online ISSN ,4-Dimethyl-3,4-dihydropyrido- [2 0,3 0 :3,4]pyrazolo[1,5-a][1,3,5]triazin-2- amine ethanol monosolvate 1 Anton V. Dolzhenko, a * Geok Kheng Tan, b Anna V. Dolzhenko, c Lip Lin Koh b and Wai Keung Chui d a School of Pharmacy, Faculty of Health Sciences, Curtin University of Technology, GPO Box U1987, Perth 6845, Western Australia, Australia, b Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, Singapore , Singapore, c Perm State Pharmaceutical Academy, 2 Polevaya Street, Perm , Russian Federation, and d Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore , Singapore Correspondence anton.dolzhenko@curtin.edu.au Received 26 November 2010; accepted 5 December 2010 Key indicators: single-crystal X-ray study; T = 100 K; mean (C C) = Å; disorder in solvent or counterion; R factor = 0.050; wr factor = 0.133; data-toparameter ratio = In the title compound, C 10 H 12 N 6 C 2 H 5 OH, the planarity of the heterocyclic system is slightly distorted at the triazine ring (r.m.s. deviation = Å), which adopts a conformation best described as intermediate between a flattened twisted boat and a half-boat with the tertiary Csp 3 atom at the bow. In the crystal, molecules form centrosymmetric dimers connected by NH O and OH N hydrogen bonds between the amino group H atom, the ethanol solvent molecule and the triazine N atom, making an R 4 4 (12) graph-set motif. The other H atom of the amino group and the H atom on the endocyclic N atom form NH N hydrogen bonds with the N atoms of the pyrazole and pyridine rings, respectively, linking the molecules into C(7)C(7) chains with the R 2 2 (8) binary graphset motif running along [010]. Related literature For a review on the synthesis and biological activity of pyrazolo[1,5-a]triazines, see: Dolzhenko et al. (2008). For the synthesis, crystal structure studies and biological activity of related fused gem-dimethyl-substituted amino-1,3,5-triazines, see: Dolzhenko et al. (2007a,b, 2009), Toyoda et al. (1997). For graph-set analysis of hydrogen bonding, see: Bernstein et al. (1995). For a related structure, see: Sachdeva et al. (2010). Experimental Crystal data C 10 H 12 N 6 C 2 H 6 O M r = Monoclinic, C2=c a = (19) Å b = (2) Å c = (3) Å = (4) Data collection Bruker SMART APEX CCD diffractometer Absorption correction: multi-scan (SADABS; Sheldrick, 2001) T min = 0.950, T max = Refinement R[F 2 >2(F 2 )] = wr(f 2 ) = S = reflections 209 parameters 38 restraints Table 1 Hydrogen-bond geometry (Å, ). V = (7) Å 3 Z =8 Mo K radiation = 0.09 mm 1 T = 100 K mm 9471 measured reflections 3129 independent reflections 2657 reflections with I > 2(I) R int = H atoms treated by a mixture of independent and constrained refinement max = 0.37 e Å 3 min = 0.21 e Å 3 D HA D H HA DA D HA N5 H5N1 i 0.86 (2) 2.16 (2) (18) (18) N6 H6BN2 i 0.90 (2) 2.08 (2) (18) (18) N6 H6AO1S ii 0.85 (2) 2.03 (2) (18) (18) O1S H1SN (2) 1.93 (2) (17) 170 (2) Symmetry codes: (i) x þ 3 2 ; y 1 2 ; z þ 3 2 ; (ii) x þ 1; y; z þ 1. Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. This work was supported by the School of Pharmacy, Curtin University of Technology, and the National Medical Research Council, Singapore (NMRC/NIG/0019/2008). Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG2760). 1 Fused heterocyclic systems with s-triazine ring. Part 16. for part 15, see Sachdeva et al. (2010). Thomson Reuters ResearcherID: B doi: /s x Dolzhenko et al. o83

2 organic compounds References Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, Bruker (2001). SMART and SAINT. Bruker AXS GmbH, Karlsruhe, Germany. Dolzhenko, A. V., Dolzhenko, A. V. & Chui, W. K. (2007a). Tetrahedron, 63, Dolzhenko, A. V., Dolzhenko, A. V. & Chui, W. K. (2008). Heterocycles, 75, Dolzhenko, A. V., Foo, M. C., Tan, B. J., Dolzhenko, A. V., Chiu, G. N. C. & Chui, W. K. (2009). Heterocycles, 78, Dolzhenko, A. V., Tan, G. K., Koh, L. L., Dolzhenko, A. V. & Chui, W. K. (2007b). Acta Cryst. E63, o2796. Sachdeva, N., Dolzhenko, A. V., Tan, G. K., Koh, L. L. & Chui, W. K. (2010). Acta Cryst. E66, o2050. Sheldrick, G. M. (2001). SADABS. University of Göttingen, Germany. Sheldrick, G. M. (2008). Acta Cryst. A64, Toyoda, T., Brobey, R. K. B., Sano, G.-I., Horii, T., Tomioka, N. & Itai, A. (1997). Biochem. Biophys. Res. Commun. 235, o84 Dolzhenko et al. C 10 H 12 N 6 C 2 H 6 O

3 supporting information [ 4,4-Dimethyl-3,4-dihydropyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazin-2-amine ethanol monosolvate Anton V. Dolzhenko, Geok Kheng Tan, Anna V. Dolzhenko, Lip Lin Koh and Wai Keung Chui S1. Comment The pyrazolo[1,5-a]triazine heterocyclic system has been recognized as a template for the construction of new potential therapeutic agents (Dolzhenko et al., 2008). However data on pyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazines are limited and no details on their structure are available. Herein, we report molecular and crystal structure of 4,4-dimethyl-3,4-dihydropyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazin-2-amine, which crystallizes with a ethanol molecule to give the title compound, C 10 H 12 N 6.C 2 H 5 OH (Fig. 1 & 2). This molecule has a close structural resemblance with some known dihydrofolate reductase inhibitors such as antimalarial drug cycloguanil and its fused analogue (Toyoda et al., 1997) (Fig. 3). Due to annular tautomerism, four tautomeric forms are theoretically possible for the compound (Fig. 4). Similarly to the previously reported (Dolzhenko et al., 2007b) related fused gem-dimethyl substituted amino-1,3,5-triazine, the compound exists in the crystal as a tautomer with the labile hydrogen atom located at the triazine nitrogen atom adjacent to the sp 3 hybridized carbon atom. The heterocyclic system is nearly planar (with r.m.s. deviation of Å) with a distortion at the triazine ring. The triazine ring adopts the conformation best described as an intermediate between a flatten twist boat and a half-boat with atoms C-8 and N-4 at the bow and the stern. The angle between the geminal flagpole and bowsprit methyl groups is (14). The N4 C7, N5 C7 and N6 C7 bond distances are similar suggesting guanidine-like electron delocalization in the N4 N6/C7 fragment of the molecule. In the crystal, the molecules form centrosymmetric dimers connected by the N HO and O HN hydrogen bonds between the amino group N6 H6A, ethanol molecule and the triazine N4 atom making a R 44 (12) graph-set motif (Bernstein et al., 1995). Another hydrogen atom of the amino group N6 H6B and the hydrogen atom at the endocyclic N5 atom act as hydrogen donors forming N HN contacts with the pyrazole and pyridine N2 and N1 atoms, respectively. They arrange molecules into the running along a [010] axis C(7)C(7) chains with the R 22 (8) binary graph-set motif. S2. Experimental 4,4-Dimethyl-3,4-dihydropyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazin-2-amine was prepared by the cyclocondensation of pyrazolo[3,4-b]pyridin-3-guanidine with acetone similarly to the previously described methods (Dolzhenko et al., 2007a; Dolzhenko et al., 2009). 1H-Pyrazolo[3,4-b]pyridin-3-guanidine (0.88 g, 5.0 mmol) and piperidine (0.30 ml, 3.0 mmol) were heated in acetone (30 ml) under reflux for 10 h. After cooling, the product was filtered and washed with acetone. Yield: 0.89 g (82%). The crystals suitable for crystallographic analysis were grown by recrystallization from ethanol. m.p. 559 K. sup-1

4 S3. Refinement All C-bound H atoms were positioned geometrically and included in the refinement in riding-motion approximation [0.95 Å for CH of pyridine ring, 0.98 Å for methyl groups, and 0.99 Å for methylenic protons; U iso (H) = 1.2U eq (C py ), U iso (H) = 1.5U eq (C Me ) and U iso (H)= 1.2U eq (C methylenic )] while the N-bound H atoms were located in a difference map and refined freely. The ethyl group of ethanol molecule was disordered into two positions with occupancy ratio of 78:22. Figure 1 The molecular structure of 4,4-dimethyl-3,4-dihydropyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazin-2-amine ethanol solvate showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. sup-2

5 Figure 2 Crystal packing in the cell (view along axis c). Figure 3 Dihydrofolate reductase inhibitors with dihydro-1,3,5-triazine ring. sup-3

6 Figure 4 Annular tautomerism in 4,4-dimethyl-3,4-dihydropyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazin-2-amine. 4,4-Dimethyl-3,4-dihydropyrido[2,3 :3,4]pyrazolo[1,5-a][1,3,5]triazin- 2-amine ethanol monosolvate Crystal data C 10 H 12 N 6 C 2 H 6 O M r = Monoclinic, C2/c Hall symbol: -C 2yc a = (19) Å b = (2) Å c = (3) Å β = (4) V = (7) Å 3 Z = 8 Data collection Bruker SMART APEX CCD diffractometer Radiation source: fine-focus sealed tube Graphite monochromator φ and ω scans F(000) = 1120 D x = Mg m 3 Melting point: 559 K Mo Kα radiation, λ = Å Cell parameters from 782 reflections θ = µ = 0.09 mm 1 T = 100 K Plate, yellow mm Absorption correction: multi-scan (SADABS; Sheldrick, 2001) T min = 0.950, T max = measured reflections 3129 independent reflections 2657 reflections with I > 2σ(I) sup-4

7 R int = θ max = 27.5, θ min = 2.3 h = Refinement Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = wr(f 2 ) = S = reflections 209 parameters 38 restraints Primary atom site location: structure-invariant direct methods k = l = Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H atoms treated by a mixture of independent and constrained refinement w = 1/[σ 2 (F o2 ) + (0.0709P) P] where P = (F o 2 + 2F c2 )/3 (Δ/σ) max = Δρ max = 0.37 e Å 3 Δρ min = 0.21 e Å 3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 ) x y z U iso */U eq Occ. (<1) O1S (10) (8) (7) (3) H1S (18) (15) (14) (6)* C1S (2) (2) (15) (7) (6) H1SA * (6) H1SB * (6) C2S (3) (3) (2) (11) (6) H2SA * (6) H2SB * (6) H2SC * (6) C1SA (9) (9) (6) (2) (6) H1SC * (6) H1SD * (6) C2SA (14) (12) (9) (4) (6) H2SD * (6) H2SE * (6) H2SF * (6) N (10) (8) (7) (3) N (10) (9) (7) (3) N (10) (8) (7) (3) N (10) (8) (7) (3) N (11) (9) (8) (3) sup-5

8 H (17) (15) (12) (5)* N (13) (10) (9) (3) H6A (17) (14) (12) (5)* H6B (17) (15) (12) (5)* C (13) (10) (9) (3) H * C (13) (11) (9) (3) H * C (12) (11) (9) (3) H * C (12) (10) (8) (3) C (12) (10) (8) (3) C (12) (10) (8) (3) C (13) (11) (9) (3) C (12) (10) (8) (3) C (17) (14) (10) (4) H9A * H9B * H9C * C (15) (12) (12) (4) H10A * H10B * H10C * Atomic displacement parameters (Å 2 ) U 11 U 22 U 33 U 12 U 13 U 23 O1S (6) (6) (6) (5) (5) (4) C1S (15) (17) (12) (12) (10) (11) C2S (2) (3) (17) (19) (14) (18) C1SA (5) (6) (4) (4) (4) (4) C2SA (8) (8) (7) (6) (6) (6) N (6) (6) (6) (5) (5) (5) N (6) (6) (6) (5) (5) (5) N (6) (6) (6) (4) (5) (4) N (6) (6) (6) (5) (5) (4) N (6) (6) (6) (5) (5) (5) N (8) (7) (7) (6) (6) (5) C (8) (7) (7) (6) (6) (6) C (7) (7) (7) (6) (6) (6) C (7) (7) (7) (5) (5) (5) C (7) (7) (7) (5) (5) (5) C (6) (7) (6) (5) (5) (5) C (7) (7) (6) (5) (5) (5) C (7) (7) (7) (6) (6) (5) C (7) (7) (7) (5) (6) (5) C (11) (10) (8) (8) (8) (7) C (9) (8) (10) (7) (8) (7) sup-6

9 Geometric parameters (Å, º) O1S C1S (3) N5 C (18) O1S C1SA (9) N5 C (19) O1S H1S 0.87 (2) N5 H (2) C1S C2S (5) N6 C (2) C1S H1SA N6 H6A 0.85 (2) C1S H1SB N6 H6B 0.90 (2) C2S H2SA C1 C (2) C2S H2SB C1 H C2S H2SC C2 C (2) C1SA C2SA 1.40 (2) C2 H C1SA H1SC C3 C (19) C1SA H1SD C3 H C2SA H2SD C4 C (2) C2SA H2SE C4 C (19) C2SA H2SF C8 C (2) N1 C (19) C8 C (2) N1 C (18) C9 H9A N2 C (18) C9 H9B N2 N (17) C9 H9C N3 C (17) C10 H10A N3 C (18) C10 H10B N4 C (19) C10 H10C N4 C (18) C1S O1S C1SA 36.3 (5) N1 C1 C (14) C1S O1S H1S (14) N1 C1 H C1SA O1S H1S (14) C2 C1 H O1S C1S C2S (3) C3 C2 C (13) O1S C1S H1SA C3 C2 H C2S C1S H1SA C1 C2 H O1S C1S H1SB C2 C3 C (13) C2S C1S H1SB C2 C3 H H1SA C1S H1SB C4 C3 H C1S C2S H2SA C3 C4 C (13) C1S C2S H2SB C3 C4 C (13) H2SA C2S H2SB C6 C4 C (12) C1S C2S H2SC N2 C5 N (12) H2SA C2S H2SC N2 C5 C (12) H2SB C2S H2SC N1 C5 C (13) C2SA C1SA O1S (11) N3 C6 N (12) C2SA C1SA H1SC N3 C6 C (12) O1S C1SA H1SC N4 C6 C (13) C2SA C1SA H1SD N4 C7 N (13) O1S C1SA H1SD N4 C7 N (14) H1SC C1SA H1SD N6 C7 N (13) C1SA C2SA H2SD N5 C8 N (11) sup-7

10 C1SA C2SA H2SE N5 C8 C (13) H2SD C2SA H2SE N3 C8 C (13) C1SA C2SA H2SF N5 C8 C (13) H2SD C2SA H2SF N3 C8 C (12) H2SE C2SA H2SF C10 C8 C (14) C1 N1 C (12) C8 C9 H9A C5 N2 N (11) C8 C9 H9B C6 N3 N (11) H9A C9 H9B C6 N3 C (12) C8 C9 H9C N2 N3 C (11) H9A C9 H9C C7 N4 C (12) H9B C9 H9C C7 N5 C (12) C8 C10 H10A C7 N5 H (13) C8 C10 H10B C8 N5 H (13) H10A C10 H10B C7 N6 H6A (13) C8 C10 H10C C7 N6 H6B (13) H10A C10 H10C H6A N6 H6B (18) H10B C10 H10C C1SA O1S C1S C2S 21.3 (7) C8 N3 C6 C (13) C1S O1S C1SA C2SA 39.4 (9) C7 N4 C6 N (2) C5 N2 N3 C (16) C7 N4 C6 C (15) C5 N2 N3 C (13) C3 C4 C6 N (17) C5 N1 C1 C2 2.2 (2) C5 C4 C6 N (15) N1 C1 C2 C3 0.2 (2) C3 C4 C6 N4 2.6 (3) C1 C2 C3 C4 2.3 (2) C5 C4 C6 N (15) C2 C3 C4 C (16) C6 N4 C7 N (14) C2 C3 C4 C5 2.0 (2) C6 N4 C7 N5 1.7 (2) N3 N2 C5 N (13) C8 N5 C7 N (2) N3 N2 C5 C (16) C8 N5 C7 N (14) C1 N1 C5 N (14) C7 N5 C8 N (18) C1 N1 C5 C4 2.4 (2) C7 N5 C8 C (14) C3 C4 C5 N (13) C7 N5 C8 C (17) C6 C4 C5 N (17) C6 N3 C8 N (18) C3 C4 C5 N1 0.4 (2) N2 N3 C8 N (12) C6 C4 C5 N (13) C6 N3 C8 C (14) N2 N3 C6 N (13) N2 N3 C8 C (19) C8 N3 C6 N4 4.4 (2) C6 N3 C8 C (17) N2 N3 C6 C (17) N2 N3 C8 C (17) Hydrogen-bond geometry (Å, º) D H A D H H A D A D H A N5 H5 N1 i 0.86 (2) 2.16 (2) (18) (18) N6 H6B N2 i 0.90 (2) 2.08 (2) (18) (18) N6 H6A O1S ii 0.85 (2) 2.03 (2) (18) (18) O1S H1S N (2) 1.93 (2) (17) 170 (2) Symmetry codes: (i) x+3/2, y 1/2, z+3/2; (ii) x+1, y, z+1. sup-8