3,4,6-Trimethyl-1-phenyl-1H-pyrazolo­[3,4-b]pyridine

In the title compound, C₁₅H₁₅N₃, the 1H-pyrazolo­[3,4-b]pyridine system and the phenyl ring are each individually planar, with r.m.s. deviations of 0.017 (2) and 0.011 (2) Å, respectively; the dihedral angle between the two aromatic systems is 9.33 (10)°. The crystal packing is stabilized by offset π–π stacking between parallel pyrazolo­[3,4-b]pyridine ring systems [face-to-face distance = 3.449 (6) Å].

Key indicators

• Single-crystal X-ray study
• T = 296 K, P = 0.0 kPa
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.068
• wR factor = 0.198
• Data-to-parameter ratio = 13.6

checkCIF/PLATON results

No syntax errors found



Alert level B
DIFMX01_ALERT_2_B  The maximum difference density is > 0.1*ZMAX*1.00
            _refine_diff_density_max given =      0.742
            Test value =      0.700
PLAT097_ALERT_2_B Large Reported Max.  (Positive) Residual Density       0.74 eA-3
PLAT230_ALERT_2_B Hirshfeld Test Diff for    N1     --  C5      ..       7.47 su

Alert level C
DIFMX02_ALERT_1_C  The maximum difference density is > 0.1*ZMAX*0.75
            The relevant atom site should be identified.
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.86
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C4     --  C8      ..       6.45 su
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          1

Alert level G
PLAT072_ALERT_2_G SHELXL First Parameter in WGHT Unusually Large.       0.10
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n

   0 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   6 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Many polysubstituted derivatives of 1 H-pyrazolo[3,4-b]pyridine have been synthesized as potentially biologically active materials (Hardy, 1984; Chu & Lynchj, 1975).

The dihedral angle between the two aromatic ring systems in the title compound, C₁₅H₁₅N₃, is 9.33 (10)°. The 1H-pyrazolo[3,4-b]pyridine and the phenyl rings are planarswith r.m.s. deviation of 0.017 (2) and 0.011 (2) Å, respectively.

The Bond lengths and angles in title compound (Fig. 1) are found to have normal values [Allen et al., 1987]. The crystal packing is stabilized by offset π-π stacking between parallel pyrazolo[3,4-b]pyridine ring sestems related by an inversion center at 1.0, 0.5, 0.0, the face-to-face distance is 3.449 (6) Å.

Related literature

For a general review of pyrazolopyridines, see: Hardy (1984). For related compounds displaying biological activity, see: Chu & Lynchj (1975). For bond-length data, see: Allen et al. (1987).

S2. Experimental

To a solution of 4-hydroxy-6-methylpyran-2-one (291 mg, 2.309 mmol) and 5-amino-3-methyl-1-phenylpyrazole (200 mg, 1.154 mmol) in 10 ml of n-butanol was added p-toluenesulfonic acid (0.12 mg).

The reaction mixture was refluxed for 42 h. After evaporation of solvent, the residue was then purified over silica gel column chromatography using a (98:2) mixture of hexane and ethyl acetate as eluent. Under these conditions the compound was obtained as colourless crystals.

S3. Refinement

All H atoms were fixed geometrically and treated as riding with C—H = 0.96 Å (methyl) and C—H = 0.93 Å (aromatic), U_iso(H) = 1.5U_eq(C) for methyl and U_iso(H) = 1.2U_eq(C) for the others.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

Fig. 1. Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small spheres of arbitrary radii.

3,4,6-Trimethyl-1-phenyl-1H-pyrazolo[3,4-b]pyridine

Crystal data

C15H15N3	F(000) = 504
Mr = 237.30	Dx = 1.276 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1348 reflections
a = 7.1714 (2) Å	θ = 2.6–25.5°
b = 12.0690 (4) Å	µ = 0.08 mm^−1
c = 14.5491 (5) Å	T = 296 K
β = 101.251 (1)°	Prism, colourless
V = 1235.05 (7) Å^3	0.32 × 0.29 × 0.12 mm
Z = 4

Data collection

Bruker X8 APEXII CCD area-detector diffractometer	1841 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.029
Graphite monochromator	θmax = 25.3°, θmin = 2.9°
φ and ω scans	h = −7→8
10642 measured reflections	k = −14→14
2252 independent reflections	l = −17→17

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.198	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.104P)^2 + 1.0638P] where P = (Fo^2 + 2Fc^2)/3
2252 reflections	(Δ/σ)max < 0.001
166 parameters	Δρmax = 0.74 e Å^−3
0 restraints	Δρmin = −0.26 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 F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² 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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.8454 (3)	0.7445 (2)	−0.04712 (18)	0.0367 (6)
C2	0.7992 (4)	0.6928 (2)	−0.13595 (19)	0.0421 (7)
C3	0.7465 (3)	0.5818 (2)	−0.14607 (17)	0.0332 (6)
C4	0.7468 (3)	0.5266 (2)	−0.06073 (18)	0.0351 (6)
C5	0.7917 (3)	0.5850 (2)	0.02285 (17)	0.0316 (6)
C6	0.9021 (4)	0.8635 (2)	−0.0425 (2)	0.0472 (7)
C7	0.6952 (4)	0.5279 (3)	−0.23948 (19)	0.0492 (8)
C8	0.7099 (3)	0.4171 (2)	−0.0326 (2)	0.0380 (7)
C9	0.6593 (4)	0.3137 (3)	−0.0909 (2)	0.0481 (8)
C10	0.8125 (3)	0.5303 (2)	0.19304 (17)	0.0317 (6)
C11	0.8164 (3)	0.4380 (2)	0.24944 (19)	0.0378 (6)
C12	0.8416 (4)	0.4501 (2)	0.3447 (2)	0.0404 (7)
C13	0.8649 (4)	0.5527 (2)	0.38535 (18)	0.0362 (6)
C14	0.8657 (4)	0.6457 (2)	0.33032 (18)	0.0356 (6)
C15	0.8396 (3)	0.6356 (2)	0.23326 (18)	0.0355 (6)
N1	0.8420 (3)	0.69504 (17)	0.03365 (15)	0.0339 (5)
N2	0.7298 (3)	0.41044 (18)	0.05772 (16)	0.0380 (6)
N3	0.7801 (3)	0.51439 (17)	0.09427 (15)	0.0332 (5)
H11	0.8019	0.3677	0.2228	0.045*
H12	0.8428	0.3877	0.3823	0.048*
H13	0.8802	0.5597	0.4501	0.043*
H14	0.8838	0.7153	0.3581	0.043*
H15	0.8401	0.6980	0.1958	0.043*
H2	0.8042	0.7343	−0.1893	0.051*
H6A	0.7931	0.9085	−0.0665	0.071*
H6B	0.9975	0.8750	−0.0796	0.071*
H6C	0.9523	0.8835	0.0214	0.071*
H7A	0.7068	0.5806	−0.2874	0.074*
H7B	0.5666	0.5016	−0.2488	0.074*
H7C	0.7792	0.4666	−0.2425	0.074*
H9A	0.7662	0.2913	−0.1173	0.072*
H9B	0.5529	0.3288	−0.1405	0.072*
H9C	0.6268	0.2554	−0.0520	0.072*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0326 (13)	0.0418 (15)	0.0371 (14)	0.0062 (11)	0.0100 (11)	−0.0020 (11)
C2	0.0459 (15)	0.0491 (17)	0.0334 (15)	0.0081 (12)	0.0129 (12)	0.0066 (12)
C3	0.0279 (12)	0.0443 (15)	0.0284 (13)	0.0109 (10)	0.0075 (10)	0.0000 (11)
C4	0.0274 (12)	0.0418 (15)	0.0358 (14)	0.0058 (10)	0.0055 (10)	−0.0037 (11)
C5	0.0251 (11)	0.0406 (14)	0.0302 (13)	0.0069 (10)	0.0082 (9)	0.0044 (10)
C6	0.0545 (17)	0.0469 (17)	0.0440 (17)	0.0002 (13)	0.0191 (13)	0.0156 (13)
C7	0.0453 (16)	0.068 (2)	0.0342 (15)	0.0045 (14)	0.0065 (12)	−0.0091 (14)
C8	0.0257 (12)	0.0334 (14)	0.0554 (18)	0.0045 (10)	0.0092 (11)	0.0069 (12)
C9	0.0431 (15)	0.0554 (19)	0.0420 (17)	0.0041 (13)	−0.0011 (12)	−0.0138 (13)
C10	0.0224 (11)	0.0444 (15)	0.0279 (12)	0.0048 (10)	0.0041 (9)	−0.0043 (11)
C11	0.0367 (13)	0.0302 (13)	0.0470 (16)	−0.0026 (10)	0.0096 (11)	−0.0034 (11)
C12	0.0430 (14)	0.0353 (15)	0.0445 (16)	0.0020 (11)	0.0127 (12)	0.0116 (12)
C13	0.0400 (14)	0.0445 (15)	0.0238 (12)	0.0081 (11)	0.0050 (10)	0.0046 (11)
C14	0.0422 (14)	0.0296 (13)	0.0338 (14)	0.0040 (11)	0.0044 (11)	−0.0049 (10)
C15	0.0394 (13)	0.0338 (13)	0.0333 (14)	0.0079 (11)	0.0072 (10)	0.0114 (11)
N1	0.0322 (11)	0.0275 (11)	0.0444 (13)	0.0041 (8)	0.0134 (9)	0.0057 (9)
N2	0.0374 (12)	0.0295 (12)	0.0460 (14)	−0.0025 (9)	0.0053 (10)	−0.0084 (10)
N3	0.0373 (11)	0.0284 (11)	0.0339 (12)	−0.0010 (9)	0.0068 (9)	−0.0026 (9)

Geometric parameters (Å, º)

C1—C6	1.491 (4)	C10—C11	1.380 (4)
C2—H2	0.9300	C11—H11	0.9300
C2—C1	1.415 (4)	C11—C12	1.370 (4)
C3—C7	1.487 (4)	C12—H12	0.9300
C3—C4	1.408 (4)	C13—H13	0.9300
C3—C2	1.392 (4)	C13—C14	1.379 (4)
C4—C8	1.424 (4)	C13—C12	1.368 (4)
C4—C5	1.388 (4)	C14—H14	0.9300
C6—H6C	0.9600	C15—H15	0.9300
C6—H6B	0.9600	C15—C10	1.397 (4)
C6—H6A	0.9600	C15—C14	1.393 (4)
C7—H7C	0.9600	N1—C5	1.377 (3)
C7—H7B	0.9600	N1—C1	1.322 (3)
C7—H7A	0.9600	N2—N3	1.383 (3)
C8—C9	1.512 (4)	N2—C8	1.296 (4)
C9—H9C	0.9600	N3—C10	1.423 (3)
C9—H9B	0.9600	N3—C5	1.359 (3)
C9—H9A	0.9600
C1—C6—H6C	109.5	C12—C13—C14	119.9 (2)
C1—C6—H6B	109.5	C12—C11—H11	120.0
C1—C6—H6A	109.5	C12—C11—C10	119.9 (2)
C1—C2—H2	118.9	C13—C12—H12	119.5
C1—N1—C5	112.6 (2)	C13—C12—C11	121.0 (2)
C2—C1—C6	118.6 (2)	C13—C14—H14	119.9
C2—C3—C7	122.1 (2)	C13—C14—C15	120.2 (2)
C2—C3—C4	114.1 (2)	C14—C13—H13	120.0
C3—C7—H7C	109.5	C14—C15—H15	120.5
C3—C7—H7B	109.5	C14—C15—C10	119.0 (2)
C3—C7—H7A	109.5	C15—C14—H14	119.9
C3—C2—H2	118.9	C15—C10—N3	121.8 (2)
C3—C2—C1	122.1 (2)	H6A—C6—H6C	109.5
C3—C4—C8	136.4 (3)	H6A—C6—H6B	109.5
C4—C8—C9	130.0 (3)	H6B—C6—H6C	109.5
C4—C3—C7	123.8 (3)	H7A—C7—H7C	109.5
C5—C4—C8	104.1 (2)	H7A—C7—H7B	109.5
C5—C4—C3	119.5 (3)	H7B—C7—H7C	109.5
C5—N3—C10	131.7 (2)	H9A—C9—H9C	109.5
C5—N3—N2	109.0 (2)	H9A—C9—H9B	109.5
C8—C9—H9C	109.5	H9B—C9—H9C	109.5
C8—C9—H9B	109.5	N1—C1—C6	116.6 (2)
C8—C9—H9A	109.5	N1—C1—C2	124.8 (3)
C8—N2—N3	107.6 (2)	N1—C5—C4	126.9 (2)
C10—C11—H11	120.0	N2—C8—C9	119.0 (2)
C10—C15—H15	120.5	N2—C8—C4	111.0 (2)
C11—C12—H12	119.5	N2—N3—C10	119.3 (2)
C11—C10—N3	118.2 (2)	N3—C5—C4	108.2 (2)
C11—C10—C15	120.0 (2)	N3—C5—N1	124.8 (2)
C12—C13—H13	120.0