Neridienone A, a pregnane from the roots of Nerium oleander

In the title compound, 12β-hydroxy­pregna-4,6,16-triene-3,20-dienone, C₂₁H₂₆O₃, rings A and B are in almost half-chair conformations, ring C is in a chair conformation and ring D is in a 14α-envelope conformation. The A/B ring junction is quasi-trans, whereas the B/C and C/D ring junctions both approach trans character. The mol­ecule as a whole is slightly convex towards the β side. Intra- and inter­molecular hydrogen bonding, together with van der Waals inter­actions, plays a major role in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.043
• wR factor = 0.097
• Data-to-parameter ratio = 7.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.71
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           25.00
           From the CIF: _reflns_number_total               1704
           Count of symmetry unique reflns         1708
           Completeness (_total/calc)             99.77%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no

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

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

---

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL.

12β-hydroxypregna-4,6,16-triene-3,20-dienone

Crystal data

C21H26O3	F(000) = 352
Mr = 326.42	Dx = 1.235 Mg m^−3
Monoclinic, P21	Melting point: 477 K
Hall symbol: P 2yb	Mo Kα radiation, λ = 0.71073 Å
a = 11.585 (2) Å	Cell parameters from 44 reflections
b = 6.242 (1) Å	θ = 4.8–12.5°
c = 12.313 (2) Å	µ = 0.08 mm^−1
β = 99.73 (1)°	T = 293 K
V = 877.6 (3) Å^3	Block, colourless
Z = 2	0.33 × 0.25 × 0.23 mm

Data collection

Bruker P4 diffractometer	Rint = 0.000
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.2°
Graphite monochromator	h = −13→13
θ/2θ scans	k = 0→7
1704 measured reflections	l = 0→14
1704 independent reflections	3 standard reflections every 97 reflections
1302 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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.097	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0456P)^2 + 0.0311P] where P = (Fo^2 + 2Fc^2)/3
1704 reflections	(Δ/σ)max < 0.001
221 parameters	Δρmax = 0.14 e Å^−3
1 restraint	Δρmin = −0.19 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	−0.2665 (3)	0.6037 (7)	0.6694 (3)	0.0586 (10)
H1A	−0.2749	0.5518	0.7419	0.070*
H1B	−0.2294	0.4914	0.6331	0.070*
C2	−0.3886 (3)	0.6472 (8)	0.6030 (3)	0.0701 (12)
H2A	−0.4330	0.5148	0.5942	0.084*
H2B	−0.4298	0.7476	0.6429	0.084*
C3	−0.3805 (3)	0.7368 (7)	0.4924 (3)	0.0602 (10)
C4	−0.2839 (3)	0.8827 (7)	0.4878 (2)	0.0552 (9)
H4	−0.2833	0.9584	0.4228	0.066*
C5	−0.1950 (3)	0.9150 (6)	0.5722 (2)	0.0441 (8)
C10	−0.1873 (3)	0.7995 (5)	0.6825 (2)	0.0419 (8)
C6	−0.0996 (3)	1.0596 (6)	0.5611 (2)	0.0528 (9)
H6	−0.1097	1.1532	0.5014	0.063*
C7	0.0011 (3)	1.0667 (6)	0.6306 (2)	0.0494 (9)
H7	0.0578	1.1645	0.6176	0.059*
C8	0.0274 (3)	0.9234 (5)	0.7294 (2)	0.0384 (7)
H8	0.0177	1.0055	0.7952	0.046*
C9	−0.0577 (3)	0.7322 (6)	0.7177 (2)	0.0370 (7)
H9	−0.0384	0.6469	0.6563	0.044*
C14	0.1507 (2)	0.8297 (6)	0.7464 (2)	0.0387 (7)
H14	0.1499	0.7262	0.6865	0.046*
C13	0.1811 (2)	0.6964 (5)	0.8538 (2)	0.0356 (7)
C12	0.0943 (3)	0.5078 (5)	0.8426 (2)	0.0406 (8)
H12	0.1081	0.4191	0.7804	0.049*
C11	−0.0319 (3)	0.5870 (6)	0.8192 (2)	0.0434 (8)
H11A	−0.0484	0.6651	0.8829	0.052*
H11B	−0.0839	0.4643	0.8083	0.052*
C15	0.2593 (3)	0.9658 (7)	0.7448 (3)	0.0582 (10)
H15A	0.2671	1.0070	0.6704	0.070*
H15B	0.2594	1.0930	0.7900	0.070*
C16	0.3522 (3)	0.8116 (7)	0.7929 (3)	0.0575 (10)
H16	0.4306	0.8252	0.7859	0.069*
C17	0.3105 (3)	0.6511 (6)	0.8474 (2)	0.0439 (8)
C20	0.3824 (3)	0.4779 (7)	0.9051 (3)	0.0537 (9)
C21	0.5034 (3)	0.4408 (9)	0.8791 (3)	0.0762 (13)
H21A	0.5363	0.3142	0.9164	0.114*
H21B	0.5522	0.5618	0.9033	0.114*
H21C	0.4988	0.4229	0.8011	0.114*
C18	0.1770 (3)	0.8254 (6)	0.9597 (2)	0.0452 (8)
H18A	0.2117	0.7428	1.0226	0.068*
H18B	0.0971	0.8571	0.9650	0.068*
H18C	0.2197	0.9567	0.9576	0.068*
C19	−0.2265 (3)	0.9603 (7)	0.7655 (2)	0.0596 (10)
H19A	−0.1790	1.0869	0.7692	0.089*
H19B	−0.2177	0.8953	0.8371	0.089*
H19C	−0.3072	0.9979	0.7415	0.089*
O1	−0.4507 (2)	0.6911 (6)	0.4097 (2)	0.0830 (9)
O2	0.3450 (2)	0.3618 (5)	0.9718 (2)	0.0701 (8)
O3	0.10374 (19)	0.3752 (4)	0.93719 (18)	0.0582 (7)
H3	0.1724	0.3411	0.9571	0.087*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.048 (2)	0.063 (3)	0.061 (2)	−0.005 (2)	−0.0011 (15)	0.009 (2)
C2	0.045 (2)	0.078 (3)	0.083 (2)	−0.011 (2)	0.0021 (18)	0.006 (2)
C3	0.0439 (19)	0.068 (3)	0.065 (2)	0.015 (2)	−0.0004 (17)	−0.014 (2)
C4	0.053 (2)	0.065 (2)	0.0463 (16)	0.011 (2)	0.0028 (15)	−0.0007 (19)
C5	0.0484 (18)	0.047 (2)	0.0358 (14)	0.0053 (18)	0.0049 (14)	−0.0003 (16)
C10	0.0466 (17)	0.0405 (19)	0.0383 (15)	0.0007 (17)	0.0065 (13)	−0.0006 (16)
C6	0.062 (2)	0.055 (2)	0.0408 (16)	0.002 (2)	0.0052 (15)	0.0136 (17)
C7	0.060 (2)	0.046 (2)	0.0415 (16)	−0.009 (2)	0.0073 (15)	0.0073 (16)
C8	0.0494 (18)	0.0307 (17)	0.0346 (14)	−0.0025 (16)	0.0056 (13)	0.0016 (14)
C9	0.0429 (16)	0.0360 (17)	0.0319 (13)	0.0008 (15)	0.0054 (12)	−0.0013 (13)
C14	0.0425 (17)	0.0395 (19)	0.0351 (14)	−0.0060 (17)	0.0090 (12)	−0.0004 (15)
C13	0.0401 (16)	0.0346 (18)	0.0316 (14)	0.0026 (16)	0.0045 (12)	0.0004 (14)
C12	0.0492 (18)	0.0366 (19)	0.0342 (14)	−0.0003 (17)	0.0023 (13)	0.0040 (15)
C11	0.0453 (19)	0.0377 (18)	0.0471 (17)	−0.0058 (17)	0.0074 (13)	0.0049 (16)
C15	0.054 (2)	0.065 (3)	0.0574 (18)	−0.010 (2)	0.0147 (16)	0.016 (2)
C16	0.0429 (19)	0.072 (3)	0.0585 (18)	−0.005 (2)	0.0120 (16)	0.002 (2)
C17	0.0408 (18)	0.048 (2)	0.0434 (16)	0.0013 (18)	0.0072 (14)	−0.0043 (17)
C20	0.049 (2)	0.059 (2)	0.0510 (18)	0.000 (2)	0.0009 (16)	−0.008 (2)
C21	0.050 (2)	0.087 (3)	0.090 (3)	0.009 (2)	0.0064 (18)	−0.007 (3)
C18	0.0518 (18)	0.047 (2)	0.0361 (14)	0.0014 (18)	0.0047 (13)	−0.0051 (16)
C19	0.065 (2)	0.067 (3)	0.0473 (17)	0.012 (2)	0.0119 (16)	−0.001 (2)
O1	0.0580 (15)	0.103 (2)	0.0780 (16)	0.0086 (18)	−0.0176 (13)	−0.0222 (18)
O2	0.0585 (15)	0.0721 (19)	0.0770 (16)	0.0100 (15)	0.0034 (13)	0.0207 (16)
O3	0.0560 (14)	0.0475 (15)	0.0693 (14)	0.0010 (14)	0.0051 (11)	0.0248 (13)

Geometric parameters (Å, º)

C1—C10	1.521 (5)	C13—C18	1.540 (4)
C1—C2	1.533 (4)	C13—C12	1.539 (4)
C1—H1A	0.9700	C13—C17	1.541 (4)
C1—H1B	0.9700	C12—O3	1.418 (3)
C2—C3	1.489 (5)	C12—C11	1.524 (4)
C2—H2A	0.9700	C12—H12	0.9800
C2—H2B	0.9700	C11—H11A	0.9700
C3—O1	1.224 (4)	C11—H11B	0.9700
C3—C4	1.452 (5)	C15—C16	1.490 (5)
C4—C5	1.349 (4)	C15—H15A	0.9700
C4—H4	0.9300	C15—H15B	0.9700
C5—C6	1.452 (5)	C16—C17	1.341 (5)
C5—C10	1.527 (4)	C16—H16	0.9300
C10—C9	1.549 (4)	C17—C20	1.472 (5)
C10—C19	1.554 (5)	C20—O2	1.228 (4)
C6—C7	1.327 (4)	C20—C21	1.508 (5)
C6—H6	0.9300	C21—H21A	0.9600
C7—C8	1.499 (4)	C21—H21B	0.9600
C7—H7	0.9300	C21—H21C	0.9600
C8—C14	1.525 (4)	C18—H18A	0.9600
C8—C9	1.539 (4)	C18—H18B	0.9600
C8—H8	0.9800	C18—H18C	0.9600
C9—C11	1.532 (4)	C19—H19A	0.9600
C9—H9	0.9800	C19—H19B	0.9600
C14—C15	1.521 (4)	C19—H19C	0.9600
C14—C13	1.551 (4)	O3—H3	0.8200
C14—H14	0.9800
C10—C1—C2	113.6 (3)	C18—C13—C17	108.0 (2)
C10—C1—H1A	108.8	C12—C13—C17	118.8 (3)
C2—C1—H1A	108.9	C18—C13—C14	114.0 (3)
C10—C1—H1B	108.9	C12—C13—C14	106.5 (2)
C2—C1—H1B	108.8	C17—C13—C14	97.9 (2)
H1A—C1—H1B	107.7	O3—C12—C11	106.4 (2)
C3—C2—C1	111.0 (3)	O3—C12—C13	114.5 (2)
C3—C2—H2A	109.4	C11—C12—C13	111.1 (3)
C1—C2—H2A	109.4	O3—C12—H12	108.2
C3—C2—H2B	109.4	C11—C12—H12	108.2
C1—C2—H2B	109.4	C13—C12—H12	108.2
H2A—C2—H2B	108.0	C12—C11—C9	113.3 (2)
O1—C3—C4	121.5 (4)	C12—C11—H11A	108.9
O1—C3—C2	122.5 (4)	C9—C11—H11A	108.9
C4—C3—C2	116.1 (3)	C12—C11—H11B	108.9
C5—C4—C3	123.8 (3)	C9—C11—H11B	108.9
C5—C4—H4	118.1	H11A—C11—H11B	107.7
C3—C4—H4	118.1	C16—C15—C14	100.2 (3)
C4—C5—C6	121.0 (3)	C16—C15—H15A	111.7
C4—C5—C10	122.5 (3)	C14—C15—H15A	111.7
C6—C5—C10	116.5 (2)	C16—C15—H15B	111.7
C1—C10—C5	109.9 (2)	C14—C15—H15B	111.7
C1—C10—C9	110.5 (3)	H15A—C15—H15B	109.5
C5—C10—C9	106.6 (2)	C17—C16—C15	112.6 (3)
C1—C10—C19	110.5 (3)	C17—C16—H16	123.7
C5—C10—C19	107.5 (3)	C15—C16—H16	123.7
C9—C10—C19	111.7 (2)	C16—C17—C20	124.6 (3)
C7—C6—C5	124.1 (3)	C16—C17—C13	108.9 (3)
C7—C6—H6	118.0	C20—C17—C13	125.9 (3)
C5—C6—H6	118.0	O2—C20—C17	121.4 (3)
C6—C7—C8	122.7 (3)	O2—C20—C21	119.8 (4)
C6—C7—H7	118.7	C17—C20—C21	118.7 (4)
C8—C7—H7	118.7	C20—C21—H21A	109.5
C7—C8—C14	113.4 (2)	C20—C21—H21B	109.5
C7—C8—C9	110.3 (2)	H21A—C21—H21B	109.5
C14—C8—C9	106.6 (2)	C20—C21—H21C	109.5
C7—C8—H8	108.8	H21A—C21—H21C	109.5
C14—C8—H8	108.8	H21B—C21—H21C	109.5
C9—C8—H8	108.8	C13—C18—H18A	109.5
C11—C9—C8	110.4 (2)	C13—C18—H18B	109.5
C11—C9—C10	115.8 (2)	H18A—C18—H18B	109.5
C8—C9—C10	113.0 (3)	C13—C18—H18C	109.5
C11—C9—H9	105.6	H18A—C18—H18C	109.5
C8—C9—H9	105.6	H18B—C18—H18C	109.5
C10—C9—H9	105.6	C10—C19—H19A	109.5
C15—C14—C8	122.8 (3)	C10—C19—H19B	109.5
C15—C14—C13	104.0 (2)	H19A—C19—H19B	109.5
C8—C14—C13	113.3 (2)	C10—C19—H19C	109.5
C15—C14—H14	105.1	H19A—C19—H19C	109.5
C8—C14—H14	105.1	H19B—C19—H19C	109.5
C13—C14—H14	105.1	C12—O3—H3	109.5
C18—C13—C12	111.2 (2)
C10—C1—C2—C3	56.0 (5)	C7—C8—C14—C13	175.4 (3)
C1—C2—C3—O1	143.4 (4)	C9—C8—C14—C13	−63.1 (3)
C1—C2—C3—C4	−36.5 (5)	C15—C14—C13—C18	74.6 (3)
O1—C3—C4—C5	−170.2 (4)	C8—C14—C13—C18	−61.0 (3)
C2—C3—C4—C5	9.8 (5)	C15—C14—C13—C12	−162.4 (3)
C3—C4—C5—C6	178.5 (3)	C8—C14—C13—C12	62.0 (3)
C3—C4—C5—C10	0.0 (5)	C15—C14—C13—C17	−39.1 (3)
C2—C1—C10—C5	−45.4 (4)	C8—C14—C13—C17	−174.8 (3)
C2—C1—C10—C9	−162.8 (3)	C18—C13—C12—O3	−51.2 (3)
C2—C1—C10—C19	73.1 (4)	C17—C13—C12—O3	75.1 (3)
C4—C5—C10—C1	18.0 (4)	C14—C13—C12—O3	−175.9 (2)
C6—C5—C10—C1	−160.5 (3)	C18—C13—C12—C11	69.4 (3)
C4—C5—C10—C9	137.8 (3)	C17—C13—C12—C11	−164.3 (2)
C6—C5—C10—C9	−40.7 (4)	C14—C13—C12—C11	−55.3 (3)
C4—C5—C10—C19	−102.3 (4)	O3—C12—C11—C9	−179.4 (3)
C6—C5—C10—C19	79.1 (3)	C13—C12—C11—C9	55.3 (3)
C4—C5—C6—C7	−165.6 (4)	C8—C9—C11—C12	−55.9 (3)
C10—C5—C6—C7	13.0 (5)	C10—C9—C11—C12	174.1 (3)
C5—C6—C7—C8	0.1 (5)	C8—C14—C15—C16	166.1 (2)
C6—C7—C8—C14	136.8 (3)	C13—C14—C15—C16	36.0 (3)
C6—C7—C8—C9	17.3 (4)	C14—C15—C16—C17	−18.6 (4)
C7—C8—C9—C11	−179.4 (2)	C15—C16—C17—C20	−178.8 (3)
C14—C8—C9—C11	57.1 (3)	C15—C16—C17—C13	−6.9 (4)
C7—C8—C9—C10	−47.9 (3)	C18—C13—C17—C16	−89.9 (3)
C14—C8—C9—C10	−171.4 (2)	C12—C13—C17—C16	142.3 (3)
C1—C10—C9—C11	−52.8 (4)	C14—C13—C17—C16	28.6 (3)
C5—C10—C9—C11	−172.2 (3)	C18—C13—C17—C20	81.8 (4)
C19—C10—C9—C11	70.7 (4)	C12—C13—C17—C20	−46.0 (4)
C1—C10—C9—C8	178.5 (2)	C14—C13—C17—C20	−159.7 (3)
C5—C10—C9—C8	59.1 (3)	C16—C17—C20—O2	164.7 (3)
C19—C10—C9—C8	−58.0 (3)	C13—C17—C20—O2	−5.8 (5)
C7—C8—C14—C15	49.2 (4)	C16—C17—C20—C21	−16.6 (5)
C9—C8—C14—C15	170.8 (2)	C13—C17—C20—C21	172.9 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···O1^i	0.97	2.42	3.391 (5)	174
O3—H3···O2	0.82	1.98	2.756 (3)	157

Symmetry code: (i) −x−1, y−1/2, −z+1.