2,6-Di­phenyl-3-iso­propyl­piperidin-4-one

In the title compound, the two phenyl rings are oriented at an angle of 63.4 (1)° with respect to each other. The 4-piperidone ring adopts a slightly distorted chair conformation. Molecules are packed through N—H...O hydrogen bond and van der Waals interactions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.063
• wR factor = 0.195
• Data-to-parameter ratio = 14.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



SHFSU_01  Alert C The absolute value of parameter shift to su ratio > 0.05
          Absolute value of the parameter shift to su ratio given   0.061
          Additional refinement cycles may be required.

WEIGH_01  Alert C Extra text has been found in the
          _refine_ls_weighting_scheme field. This should be in the
          _refine_ls_weighting_details field.
          Weighting scheme given as calc w = 1/[\s^2^(Fo^2^)+(0.1P)^2^] where P
          Weighting scheme identified as calc

PLAT_711  Alert C BOND    Unknown or Inconsistent Label ........       H1B
                           N1     H1B

PLAT_712  Alert C ANGLE   Unknown or Inconsistent Label ........       H1B
                           C6     N1     H1B

PLAT_712  Alert C ANGLE   Unknown or Inconsistent Label ........       H1B
                           C2     N1     H1B

PLAT_712  Alert C ANGLE   Unknown or Inconsistent Label ........       H1B
                           H1B    N1     H1


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 6 Alert Level C = Please check

---

S1. Comment

The piperidine ring is a characteristic feature of antihistaminic agents, oral anesthetics, narcotic analgesics, tranquillizers and hypotensive agents (Robinson, 1973). Many piperidine derivatives also form the skeleton of several alkaloids (Hootele et al., 1980). Several 2,6-substituted piperidine derivatives are found to possess fungicidal, herbicidal and bactericidal activities (Mobio et al., 1989). A large variety of 4-piperidones with different substituents in the 1, 2, 3, 5 and 6 positions with further substitutions in the 2- and 6-substituent phenyl rings are reported elsewhere (Jia et al., 1989a,b; Cheer et al., 1984; Sekar et al., 1990, 1993; Sukumar et al., 1994; Diaz et al., 1997). Continuing this series, we report here the structure of 2,6-diphenyl-3-isopropylpiperidin-4-one.

Colourless prism-shaped crystals obtained during the synthesis were suitable for X-ray crystallography.

Fig. 1 shows the molecular structure; bond lengths and angles are given in Table. 1. The piperidine ring adopts a slightly distorted chair conformation. Atoms C2, C3, C5 and C6 lie in a plane, whereas N1 and C4 deviate by -0.703 (3) and 0.518 (4) Å on either side of this plane. The phenyl rings are planar, with a maximum deviation of -0.009 (4) Å for ring A (C7–C8) and 0.003 (5) Å for ring B (C13–C14), and are cis to the piperidine ring [C5—C6—C7—C8 = 59.0 (5)°; C3—C2—C13—C14 = -72.5 (4)°]. The dihedral angle between the two phenyl rings is 63.4 (1)°.

The bond lengths of the rings vary from 1.352 (5) to 1.386 (5) Å. The bond lengths C6—C7 [1.513 (5) Å] and C2—C13 [1.503 (5) Å] are in good agreement with the overall distances of Csp₃—C_ar [1.513 (14) Å] (Allen et al., 1987). The endocyclic angles C7—C8—C12 [117.3 (3)°] and C13—C14—C18 [117.8 (3)°] are smaller than the average value of 120° as observed in related structures (Singh et al., 1990; Eswaramoorthy, 1992). This may be due to conjugation.

Molecules are packed in chains running along the b axis. These continuous chains are stabilized by N—H···O intermolecular hydrogen bonds (Table 2). Further stabilization is provided by the shortest C—H···O contact and by van der Waals interactions.

S2. Experimental

The procedure adopted for the preparation of the title heterocyclic compound is similar to that of Noller & Baliah (1948). 0.2 mol of ammonium acetate was dissolved in 30 ml of rectified spirit, and 0.4 mol of benzaldehyde and 0.2 mol of isobutylmethyl ketone were added to this solution. The mixture was heated to boiling point and set aside for a day. The oily base obtained was converted into its hydrochloride by the addition of concentrated hydrochloric acid and the separated solid was filtered, dried and recrystallized from absolute ethanol. To the hydrochloride, a few drops of acetone were added and the mixture was neutralized with liquid ammonia. On dilution with water, the free base was separated and was filtered and recrystallized from absolute ethanol; m.p. 398–399 K.

S3. Refinement

All H atoms were fixed geometrically and refined isotropically using a riding model with N—H = 0.86, C—H(aromatic) = 0.93 and C—H(aliphatic) = 0.98 Å.

Computing details

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Enraf Nonius, 1994); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1997) and PLUTON (Spek, 1997); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1983, 1995).

Figures

Fig. 1. The molecular structure of the title compound, showing the atom-labelling scheme and 50% probability level displacement ellipsoids for the non-H atoms.

2,6-Diphenyl-3-isopropylpiperidin-4-one

Crystal data

C20H23NO	F(000) = 632
Mr = 293.39	Dx = 1.179 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.6008 (8) Å	Cell parameters from 25 reflections
b = 13.459 (3) Å	θ = 6.2–11.6°
c = 12.0597 (12) Å	µ = 0.07 mm^−1
β = 118.611 (9)°	T = 293 K
V = 1653.0 (5) Å^3	Prism, colourless
Z = 4	0.4 × 0.3 × 0.2 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.030
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.0°
Graphite monochromator	h = −13→12
ω/2θ scans	k = 0→15
3046 measured reflections	l = 0→14
2897 independent reflections	3 standard reflections every 100 reflections
1320 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.063	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.195	H-atom parameters constrained
S = 0.96	Calculated w = 1/[σ^2(Fo^2) + (0.1P)^2] where P = (Fo^2 + 2Fc^2)/3
2897 reflections	(Δ/σ)max = 0.061
201 parameters	Δρmax = 0.20 e Å^−3
0 restraints	Δρmin = −0.24 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	Occ. (<1)
N1	0.5202 (2)	0.1941 (2)	0.7886 (3)	0.0405 (7)
H1B	0.5698	0.1911	0.8731	0.049*	0.00
H1	0.4879	0.2562	0.7683	0.049*
C2	0.6028 (3)	0.1737 (3)	0.7300 (3)	0.0442 (9)
H2	0.5458	0.1678	0.6386	0.053*
C3	0.6728 (3)	0.0727 (3)	0.7803 (4)	0.0473 (10)
H3	0.7260	0.0812	0.8718	0.057*
C4	0.5729 (3)	−0.0056 (3)	0.7628 (4)	0.0506 (10)
C5	0.4696 (4)	0.0224 (3)	0.7980 (4)	0.0629 (12)
H5A	0.5075	0.0215	0.8892	0.075*
H5B	0.3997	−0.0265	0.7638	0.075*
C6	0.4124 (3)	0.1247 (3)	0.7489 (4)	0.0497 (10)
H6	0.3665	0.1222	0.6564	0.060*
C7	0.3143 (3)	0.1550 (3)	0.7917 (4)	0.0475 (10)
C8	0.3469 (4)	0.1622 (3)	0.9170 (4)	0.0594 (11)
H8	0.4334	0.1508	0.9783	0.071*
C9	0.2553 (4)	0.1857 (3)	0.9543 (4)	0.0702 (13)
H9	0.2793	0.1885	1.0397	0.084*
C10	0.1284 (4)	0.2048 (3)	0.8649 (5)	0.0688 (13)
H10	0.0659	0.2210	0.8892	0.083*
C11	0.0944 (4)	0.1999 (3)	0.7405 (4)	0.0652 (12)
H11	0.0083	0.2134	0.6798	0.078*
C12	0.1856 (4)	0.1755 (3)	0.7035 (4)	0.0558 (11)
H12	0.1606	0.1726	0.6179	0.067*
C13	0.6972 (3)	0.2577 (3)	0.7539 (3)	0.0403 (9)
C14	0.7737 (3)	0.2965 (3)	0.8731 (4)	0.0503 (10)
H14	0.7668	0.2699	0.9409	0.060*
C15	0.8593 (3)	0.3732 (3)	0.8941 (4)	0.0598 (11)
H15	0.9099	0.3980	0.9753	0.072*
C16	0.8703 (4)	0.4131 (3)	0.7959 (5)	0.0605 (11)
H16	0.9279	0.4655	0.8097	0.073*
C17	0.7972 (4)	0.3762 (3)	0.6782 (4)	0.0576 (11)
H17	0.8055	0.4034	0.6115	0.069*
C18	0.7100 (3)	0.2986 (3)	0.6550 (3)	0.0481 (10)
H18	0.6603	0.2742	0.5735	0.058*
O19	0.5786 (3)	−0.0892 (2)	0.7304 (3)	0.0762 (9)
C20	0.7701 (4)	0.0440 (3)	0.7332 (4)	0.0594 (11)
H20	0.8233	0.1033	0.7432	0.071*
C21	0.7080 (5)	0.0162 (4)	0.5963 (5)	0.0956 (17)
H21A	0.7752	0.0062	0.5725	0.143*
H21B	0.6505	0.0687	0.5462	0.143*
H21C	0.6585	−0.0439	0.5825	0.143*
C22	0.8642 (4)	−0.0352 (4)	0.8179 (5)	0.0970 (18)
H22A	0.8193	−0.0978	0.8016	0.145*
H22B	0.8960	−0.0171	0.9048	0.145*
H22C	0.9369	−0.0407	0.8011	0.145*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0365 (15)	0.0319 (16)	0.0588 (19)	−0.0001 (13)	0.0274 (15)	0.0009 (14)
C2	0.0402 (19)	0.043 (2)	0.057 (2)	−0.0055 (17)	0.0290 (18)	−0.0048 (18)
C3	0.0413 (19)	0.045 (2)	0.063 (2)	0.0015 (18)	0.0305 (18)	−0.0018 (19)
C4	0.050 (2)	0.037 (2)	0.074 (3)	0.0006 (19)	0.036 (2)	−0.004 (2)
C5	0.059 (2)	0.044 (3)	0.106 (3)	−0.004 (2)	0.057 (3)	0.001 (2)
C6	0.041 (2)	0.047 (2)	0.071 (3)	−0.0033 (18)	0.0355 (19)	−0.005 (2)
C7	0.039 (2)	0.043 (2)	0.066 (3)	−0.0054 (17)	0.030 (2)	−0.002 (2)
C8	0.046 (2)	0.065 (3)	0.066 (3)	0.005 (2)	0.026 (2)	−0.004 (2)
C9	0.071 (3)	0.083 (3)	0.072 (3)	0.004 (3)	0.046 (3)	−0.007 (3)
C10	0.060 (3)	0.073 (3)	0.094 (4)	0.005 (2)	0.054 (3)	−0.008 (3)
C11	0.038 (2)	0.066 (3)	0.087 (3)	0.007 (2)	0.028 (2)	−0.003 (3)
C12	0.051 (2)	0.061 (3)	0.061 (3)	0.004 (2)	0.031 (2)	0.006 (2)
C13	0.0355 (17)	0.044 (2)	0.046 (2)	0.0017 (17)	0.0235 (17)	−0.0031 (18)
C14	0.053 (2)	0.049 (2)	0.053 (3)	−0.003 (2)	0.029 (2)	0.000 (2)
C15	0.044 (2)	0.066 (3)	0.069 (3)	−0.011 (2)	0.027 (2)	−0.016 (2)
C16	0.048 (2)	0.050 (3)	0.098 (3)	−0.008 (2)	0.047 (2)	−0.008 (3)
C17	0.061 (2)	0.056 (3)	0.073 (3)	−0.003 (2)	0.046 (2)	0.003 (2)
C18	0.042 (2)	0.058 (3)	0.048 (2)	0.0042 (18)	0.0254 (18)	−0.001 (2)
O19	0.078 (2)	0.0398 (18)	0.138 (3)	−0.0056 (15)	0.074 (2)	−0.0108 (18)
C20	0.054 (2)	0.049 (3)	0.097 (3)	−0.004 (2)	0.053 (2)	−0.011 (2)
C21	0.113 (4)	0.106 (4)	0.103 (4)	−0.003 (3)	0.080 (3)	−0.012 (3)
C22	0.065 (3)	0.094 (4)	0.142 (5)	0.027 (3)	0.058 (3)	0.007 (3)

Geometric parameters (Å, º)

N1—C6	1.447 (4)	C10—H10	0.930
N1—C2	1.463 (4)	C11—C12	1.370 (5)
N1—H1B	0.900	C11—H11	0.930
N1—H1	0.900	C12—H12	0.930
C2—C13	1.503 (5)	C13—C14	1.381 (5)
C2—C3	1.550 (5)	C13—C18	1.384 (5)
C2—H2	0.980	C14—C15	1.370 (5)
C3—C4	1.504 (5)	C14—H14	0.930
C3—C20	1.537 (5)	C15—C16	1.360 (5)
C3—H3	0.980	C15—H15	0.930
C4—O19	1.204 (4)	C16—C17	1.352 (5)
C4—C5	1.498 (5)	C16—H16	0.930
C5—C6	1.520 (5)	C17—C18	1.386 (5)
C5—H5A	0.970	C17—H17	0.930
C5—H5B	0.970	C18—H18	0.930
C6—C7	1.513 (5)	C20—C22	1.518 (6)
C6—H6	0.980	C20—C21	1.499 (6)
C7—C8	1.375 (5)	C20—H20	0.980
C7—C12	1.385 (5)	C21—H21A	0.960
C8—C9	1.375 (5)	C21—H21B	0.960
C8—H8	0.930	C21—H21C	0.960
C9—C10	1.369 (6)	C22—H22A	0.960
C9—H9	0.930	C22—H22B	0.960
C10—C11	1.358 (6)	C22—H22C	0.960
C6—N1—C2	112.4 (3)	C9—C10—H10	120.1
C6—N1—H1B	109.1	C12—C11—C10	120.6 (4)
C2—N1—H1B	109.1	C12—C11—H11	119.7
C6—N1—H1	109.1	C10—C11—H11	119.7
C2—N1—H1	109.1	C11—C12—C7	121.0 (4)
H1B—N1—H1	107.9	C11—C12—H12	119.5
N1—C2—C13	110.7 (3)	C7—C12—H12	119.5
N1—C2—C3	108.5 (3)	C14—C13—C18	117.8 (3)
C13—C2—C3	112.8 (3)	C14—C13—C2	122.0 (3)
N1—C2—H2	108.3	C18—C13—C2	120.2 (3)
C13—C2—H2	108.3	C15—C14—C13	121.7 (4)
C3—C2—H2	108.3	C15—C14—H14	119.2
C4—C3—C2	109.6 (3)	C13—C14—H14	119.2
C4—C3—C20	115.2 (3)	C14—C15—C16	119.9 (4)
C2—C3—C20	114.6 (3)	C14—C15—H15	120.1
C4—C3—H3	105.5	C16—C15—H15	120.1
C2—C3—H3	105.5	C17—C16—C15	119.7 (4)
C20—C3—H3	105.5	C17—C16—H16	120.1
O19—C4—C3	122.8 (3)	C15—C16—H16	120.1
O19—C4—C5	120.2 (3)	C16—C17—C18	121.3 (4)
C3—C4—C5	116.8 (3)	C16—C17—H17	119.4
C4—C5—C6	112.1 (3)	C18—C17—H17	119.4
C4—C5—H5A	109.2	C17—C18—C13	119.7 (3)
C6—C5—H5A	109.2	C17—C18—H18	120.2
C4—C5—H5B	109.2	C13—C18—H18	120.2
C6—C5—H5B	109.2	C22—C20—C21	112.2 (4)
H5A—C5—H5B	107.9	C22—C20—C3	110.3 (3)
N1—C6—C7	112.6 (3)	C21—C20—C3	114.8 (3)
N1—C6—C5	108.0 (3)	C22—C20—H20	106.3
C7—C6—C5	111.8 (3)	C21—C20—H20	106.3
N1—C6—H6	108.1	C3—C20—H20	106.3
C7—C6—H6	108.1	C20—C21—H21A	109.5
C5—C6—H6	108.1	C20—C21—H21B	109.5
C8—C7—C12	117.3 (3)	H21A—C21—H21B	109.5
C8—C7—C6	122.5 (3)	C20—C21—H21C	109.5
C12—C7—C6	120.2 (4)	H21A—C21—H21C	109.5
C7—C8—C9	121.8 (4)	H21B—C21—H21C	109.5
C7—C8—H8	119.1	C20—C22—H22A	109.5
C9—C8—H8	119.1	C20—C22—H22B	109.5
C10—C9—C8	119.6 (4)	H22A—C22—H22B	109.5
C10—C9—H9	120.2	C20—C22—H22C	109.5
C8—C9—H9	120.2	H22A—C22—H22C	109.5
C11—C10—C9	119.7 (4)	H22B—C22—H22C	109.5
C11—C10—H10	120.1
C6—N1—C2—C13	169.3 (3)	C7—C8—C9—C10	−1.5 (7)
C6—N1—C2—C3	−66.4 (4)	C8—C9—C10—C11	0.3 (7)
N1—C2—C3—C4	52.3 (4)	C9—C10—C11—C12	0.4 (7)
C13—C2—C3—C4	175.3 (3)	C10—C11—C12—C7	0.1 (6)
N1—C2—C3—C20	−176.4 (3)	C8—C7—C12—C11	−1.2 (6)
C13—C2—C3—C20	−53.5 (4)	C6—C7—C12—C11	177.8 (4)
C2—C3—C4—O19	140.5 (4)	N1—C2—C13—C14	49.2 (4)
C20—C3—C4—O19	9.6 (6)	C3—C2—C13—C14	−72.5 (4)
C2—C3—C4—C5	−44.3 (5)	N1—C2—C13—C18	−130.8 (3)
C20—C3—C4—C5	−175.3 (3)	C3—C2—C13—C18	107.5 (4)
O19—C4—C5—C6	−139.9 (4)	C18—C13—C14—C15	0.2 (5)
C3—C4—C5—C6	44.8 (5)	C2—C13—C14—C15	−179.8 (3)
C2—N1—C6—C7	−170.6 (3)	C13—C14—C15—C16	0.1 (6)
C2—N1—C6—C5	65.5 (4)	C14—C15—C16—C17	−0.5 (6)
C4—C5—C6—N1	−52.0 (4)	C15—C16—C17—C18	0.5 (6)
C4—C5—C6—C7	−176.4 (3)	C16—C17—C18—C13	−0.1 (5)
N1—C6—C7—C8	−62.9 (5)	C14—C13—C18—C17	−0.2 (5)
C5—C6—C7—C8	59.0 (5)	C2—C13—C18—C17	179.8 (3)
N1—C6—C7—C12	118.1 (4)	C4—C3—C20—C22	−70.2 (5)
C5—C6—C7—C12	−120.0 (4)	C2—C3—C20—C22	161.3 (3)
C12—C7—C8—C9	1.9 (6)	C4—C3—C20—C21	57.7 (5)
C6—C7—C8—C9	−177.1 (4)	C2—C3—C20—C21	−70.8 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O19^i	0.90	2.22	3.101 (4)	166
C9—H9···O19^ii	0.93	2.80	3.584 (6)	143

Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x+1, −y, −z+2.