Crystallography Reports, Vol. 46, No. 6, 2001, pp. 963–966. From Kristallografiya, Vol. 46, No. 6, 2001, pp. 1045–1048.Original English Text Copyright © 2001 by Rajnikant, Gupta, Khan, Shafi, Hashmi, Shafiullah, Varghese, Dinesh.

STRUCTURE OF ORGANIC COMPOUNDS

Crystal Structure of Cholest-4-Ene-3,6-Dione: A Steroid* Rajnikant1, **, V. K. Gupta2, E. H. Khan2, S. Shafi2, S. Hashmi2, Shafiullah2,

B. Varghese3, and Dinesh1

1 X-ray Crystallography Laboratory, Post-Graduate Department of Physics, University of Jammu, Jammu Tawi, 180006 India

2 Steroid Research Laboratory, Department of Chemistry, Aligarh Muslim University, Aligarh, 202002 India3 Regional Sophisticated Instrumentation Center, Indian Institute of Technology, Chennai, 600036 India

e-mail: rajni_kant_verma@hotmail.comReceived July 27, 2000; in final form, December 7, 2000

Abstract—The crystal structure of cholest-4-ene-3,6-dione (C27H44O2) has been determined by X-ray diffractionmethods. The compound crystallizes in the monoclinic crystal system (space group P21) with the unit cell parametersa = 10.503(4) Å, b = 8.059(1) Å, c = 14.649(1) Å, β = 105.4(2)°, and Z = 2. The structure has been refined to anR value of 0.035 for 2252 observed reflections. Ring A of the steroid nucleus exists in a sofa conformation, while ringsB and C adopt a chair conformation. The five-membered ring D exhibits a half-chair conformation. The molecules inthe unit cell are linked together by the C–H···O hydrogen bonds. © 2001 MAIK “Nauka/Interperiodica”.

INTRODUCTIONSteroids are known to have multifaceted biological

properties [1–3]. The present work is a part of our sys-tematic research on the synthesis and structure analysisof a variety of steroidal molecules [4–13].

EXPERIMENTALThe title compound was synthesized by the reaction

shown in Fig. 1.Pyridinium dichromate (44 g) was added to a solu-

tion of cholesterol (10 g) and N,N-dimethylformamide(220 ml), and the reaction mixture was stirred at roomtemperature for 4 h. The reaction was monitored withthe help of thin-layer chromatography. After comple-tion of the reaction, water was added and the reactionmixture was treated with ether. The ether layer waswashed with water, dilute HCl, and sodium bicarbonate(5%) and then was dried over anhydrous sodium sul-fate. Slow evaporation of the solvent yielded a yellowsolid, which was crystallized from methanol.

* This article was submitted by the authors in English.** Author for correspondence.

1063-7745/01/4606- $21.00 © 200963

Rectangular platelike crystals of cholest-4-ene-3,6-dione (the melting point is 397 K) were grown frommethanol by slow evaporation at room temperature.Three-dimensional intensity data were collected on anEnraf–Nonius CAD4 diffractometer (CuKα radiation,λ = 1.5418 Å, ω/2θ scan mode). The unit cell parame-ters were refined from accurately determined 25 reflec-tions in the range 14.5° < θ < 26.5°. A total of2568 reflections were measured, of which 2433 reflec-tions were found to be unique (0 ≤ h ≤ 12, 0 ≤ k ≤ 9, –17 ≤l ≤ 17) and 2252 reflections were treated as observed

[Fo > 4σ(Fo)]. Two standard reflections ( and )measured every 100 reflections showed no significantvariation in the intensity data. The reflection data werecorrected for Lorentz and polarization effects. Noabsorption and extinction corrections were applied. Thecrystallographic data are listed in Table 1.

The structure was solved by the direct method usingSHELXS86 program [14]. All the non-hydrogen atomsof the molecule were located from the E-map. The R-factor based on E-values converged to RE = 0.209.Refinement of the structure was carried out by the full-matrix least-squares method using SHELXL93 pro-

135 034

C8H17

HO

C8H17

OO

Pyridinium dichromate

N,N-dimethylformamide

Fig. 1.

01 MAIK “Nauka/Interperiodica”

964

RAJNIKANT

et al

.

Table 1. Crystal data and experimental details

Crystal habit Rectangular plates

Empirical formula C27H44O2

Molecular weight 398.63

Unit cell volume 1195.4(5) Å3

Unit cell parameters a = 10.503(4) Å, b = 8.059(1) Å,

c = 14.649(1) Å, β = 105.4(2)°Crystal system, space group Monoclinic, P21

Density (calcd) 1.1076 mg/m3

No. of molecules per unit cell 2

Linear absorption coefficient (µ) 0.513 mm–1

F(000) 440

Crystal size 0.3 × 0.2 × 0.1 mm

θ range for data collection 3.13° ≤ θ ≤ 69.92°Data/restraints/parameters 2429/1/431

Final R-factors R1 = 0.035, wR2 = 0.136

Absolute structure parameter 0.4(5)

Extinction coefficient 0.005(1)

Final residual electron density –0.11 < ∆ρ < 0.19 e Å–3

Maximum ratio ∆/σ 0.955 for H (221)

Table 2. Atomic coordinates and equivalent isotropic thermal parameters (Å2) (e.s.d.’s are given in parentheses) for the non-hydrogen atoms

Atom x y z Atom x y z

O(1) 0.8958(4) 0.2605(6) –0.1805(2) 0.134(2) C(14) 0.5198(2) 0.1625(3) 0.2032(2) 0.048(1)

O(2) 0.7537(3) –0.1592(3) 0.0180(2) 0.092(1) C(15) 0.4769(4) 0.0187(3) 0.2568(2) 0.067(1)

C(1) 0.7983(4) 0.4387(4) 0.0175(3) 0.076(1) C(16) 0.3811(4) 0.1020(4) 0.3065(2) 0.069(1)

C(2) 0.8920(4) 0.4206(5) –0.0465(3) 0.086(1) C(17) 0.3932(2) 0.2927(3) 0.2950(2) 0.052(1)

C(3) 0.8659(3) 0.2702(6) –0.1065(2) 0.081(1) C(18) 0.6430(3) 0.3011(4) 0.3593(2) 0.064(1)

C(4) 0.8070(3) 0.1282(4) –0.0698(2) 0.065(1) C(19) 0.9177(3) 0.2621(5) 0.1572(2) 0.072(1)

C(5) 0.7753(2) 0.1310(3) 0.0130(2) 0.051(1) C(20) 0.3703(3) 0.3889(4) 0.3803(2) 0.059(1)

C(6) 0.7219(3) –0.0257(3) 0.0432(2) 0.057(1) C(21) 0.3912(4) 0.5766(5) 0.3752(3) 0.075(1)

C(7) 0.6232(3) –0.0106(3) 0.1001(2) 0.057(1) C(22) 0.2302(3) 0.3550(5) 0.3901(2) 0.066(1)

C(8) 0.6424(2) 0.1394(3) 0.1670(2) 0.045(1) C(23) 0.2157(3) 0.3816(5) 0.4896(2) 0.065(1)

C(9) 0.6648(2) 0.2960(3) 0.1141(2) 0.044(1) C(24) 0.0763(3) 0.3548(4) 0.4984(2) 0.057(1)

C(10) 0.7900(2) 0.2835(3) 0.0757(2) 0.050(1) C(25) 0.0559(3) 0.3879(3) 0.5965(2) 0.056(1)

C(11) 0.6641(3) 0.4536(3) 0.1727(2) 0.057(1) C(26) 0.1368(4) 0.2719(6) 0.6716(2) 0.078(1)

C(12) 0.5429(3) 0.4671(3) 0.2129(2) 0.052(1) C(27) –0.0893(3) 0.3755(5) 0.5931(3) 0.075(1)

C(13) 0.5277(2) 0.3133(3) 0.2699(1) 0.047(1)

* Ueq = (1/3) .

Ueq* Ueq

*

Uijai* a j

* aia j( )j

∑i

∑

gram [15]. The positional and thermal parameters ofnon-hydrogen atoms were refined isotropically with theresidual index R = 0.129. Further refinement withanisotropic thermal parameters resulted in the final reli-

C

ability index R = 0.035 with weighted R (F2) = 0.136.All the hydrogen atoms were located from the differ-ence Fourier map. Their positional and isotropic tem-perature factors were refined.

RYSTALLOGRAPHY REPORTS Vol. 46 No. 6 2001

CRYSTAL STRUCTURE 965

Table 3. Endocyclic torsion angles (deg) (e.s.d.’s are given in parentheses)

C(2)–C(1)–C(10)–C(5) –45.5(4) C(14)–C(8)–C(9)–C(11) 51.1(3)

C(10)–C(1)–C(2)–C(3) 51.3(4) C(8)–C(9)–C(10)–C(5) 56.4(3)

C(1)–C(2)–C(3)–C(4) –27.7(5) C(8)–C(9)–C(11)–C(12) –50.7(3)

C(2)–C(3)–C(4)–C(5) 1.0(5) C(9)–C(11)–C(12)–C(13) –54.3(3)

C(3)–C(4)–C(5)–C(10) 3.3(5) C(11)–C(12)–C(13)–C(14) 56.5(2)

C(4)–C(5)–C(10)–C(1) 19.4(4) C(12)–C(13)–C(14)–C(8) –60.7(2)

C(6)–C(5)–C(10)–C(9) –41.4(3) C(14)–C(13)–C(17)–C(16) 39.6(2)

C(10)–C(5)–C(6)–C(7) 31.6(4) C(17)–C(13)–C(14)–C(15) 47.2(2)

C(5)–C(6)–C(7)–C(8) –33.1(3) C(13)–C(14)–C(15)–C(16) 36.0(3)

C(6)–C(7)–C(8)–C(9) 47.0(3) C(14)–C(15)–C(16)–C(17) –10.3(3)

C(7)–C(8)–C(9)–C(10) –60.3(3) C(15)–C(16)–C(17)–C(13) –18.6(3)

C(9)–C(8)–C(14)–C(13) –58.4(3)

RESULTS AND DISCUSSION

The final positional and equivalent isotropic dis-placement parameters for all the non-hydrogen atomsare listed in Table 2. The endocyclic torsion angles arepresented in Table 3. A general view of the moleculewith the atomic numbering scheme (thermal ellipsoidsare drawn at a 50% probability) is shown in Fig. 2 [16].The geometric calculations were performed usingPARST program [17].

Bond distances and bond angles are in good agree-ment with some analogous steroids [4–6, 18]. The

CRYSTALLOGRAPHY REPORTS Vol. 46 No. 6 200

mean bond lengths [C(sp3)–C(sp3), 1.537(4) Å; C(sp3)–C(sp2), 1.498(5) Å; and C(sp2)–C(sp2), 1.435(3) Å] arealso quite close to their theoretical values [19, 20]. Inring A, the C(2)–C(3) bond length [1.479(6) Å] isslightly shorter than its theoretical value [19]. Theshortening of the C(2)–C(3) bond in the structure underinvestigation can be due to the location of the ketonegroup at the C(3) atom. The endocyclic bond angles inthe steroid nucleus fall in the range from 106.7(2)° to123.4(2)° [the average value is 113.9(2)°] for the six-

C(21) C(23)

C(25)

C(26)

C(27)

C(24)

C(22)

C(17)

C(16)

C(15)

C(14)D

C(10)BA

ëC(13)

C(9)

C(12)

C(11)

C(18)

C(8)

C(7)

C(6)

O(2)C(4)

C(5)

O(1)

C(3)

C(2)

C(1) C(19)

Fig. 2. A general view of the molecule and the atomic numbering.

C(20)

1

966 RAJNIKANT et al.

membered rings and from 99.5(2)° to 107.2 (2)° [theaverage value is 103.6(4)°] for the five-membered ring.

Ring A adopts a sofa conformation with an asymme-try parameter ∆Cs = 6.01 [21]. The average value of tor-sion angles in this ring is 24.7(4)°. Ring B exists in adistorted chair conformation [∆C2 = 8.88 and ∆Cs =4.01]. The average value of torsion angles in this ring is45.0(3)°. Ring C also exists in a chair conformation[∆C2 = 2.67 and ∆Cs = 3.38]. The average value of tor-sion angles in this ring is 55.3(3)°. The five-memberedring D occurs in a half-chair conformation [∆C2 =6.38], the phase angle of pseudorotation is ∆ = −3.8°,and the maximum torsion angle ϕm = –47.2° [22]. Theaverage value of torsion angles in this ring is 30.4(3)°.There exists one intramolecular and two intermolecularC–H···O hydrogen bonds (see Table 4), which contrib-ute to the stability of the crystal structure.

ACKNOWLEDGMENTS

Rajnikant acknowledges the support of the Univer-sity Grant Commission, New Delhi, Government ofIndia for research funding under the DSA ResearchProgram, project no. F 530/1/DSA/95(SAP-I).

REFERENCES

1. W. L. Duax, C. M. Weeks, and D. C. Rohrer, in Topics inStereochemistry, Ed. by N. L. Allinger and E. L. Eliel(Wiley, New York, 1976), Vol. 9, p. 271.

2. E. V. Jensen and E. R. Desombre, Annu. Rev. Biochem.41, 203 (1972).

Table 4. Geometry of intramolecular and intermolecularC–H⋅⋅⋅O hydrogen bonds (e.s.d.’s are given in parentheses)

C–H⋅⋅⋅O H⋅⋅⋅O(Å) C⋅⋅⋅O(Å) C–H⋅⋅⋅O(deg)

C4–H41⋅⋅⋅O2 2.44(6) 2.776(4) 99(4)

C1–H12⋅⋅⋅O2(i) 2.57(6) 3.274(4) 122(4)

C27–H271⋅⋅⋅O1(ii) 2.66(5) 3.487(6) 144(3)

Note: Symmetry codes: (i) x, y + 1, z and (ii) x – 1, y, z + 1.

C

3. H. G. Williams-Ashman and A. H. Reddi, Annu. Rev.Physiol. 33, 31 (1971).

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12. Rajnikant, V. K. Gupta, J. Firoz, et al., Cryst. Res. Tech-nol. (in press).

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14. G. M. Sheldrick, SHELXS86: Program for the Solutionof Crystal Structures (Univ. of Göttingen, Göttingen,1986).

15. G. M. Sheldrick, SHELXL93: Program for the Refine-ment of Crystal Structures (Univ. of Göttingen, Göttin-gen, 1993).

16. C. K. Johnson, ORTEP-II: A Fortran Thermal EllipsoidPlot Program for Crystal Structure Illustrations, ORNL-5138 (Oak Ridge National Laboratory, Tennessee,1976).

17. M. Nardelli, Comput. Chem. 7, 95 (1993).18. R. Radhakrishnan, M. A. Viswamitra, K. K. Bhutani, and

R. M. Vaid, Acta Crystallogr., Sect. C: Cryst. Struct.Commun. 44, 1820 (1988).

19. L. E. Sutton, Tables of Interatomic Distances and Con-figuration in Molecules and Ions (The Chemical Society,London, 1965), Spec. Publ. Chem. Soc., No. 18.

20. L. S. Bartell and R. A. Bonhan, J. Chem. Phys. 32, 824(1960).

21. W. L. Duax and D. A. Norton, Atlas of Steroid Structure(Plenum, New York, 1975), Vol. 1.

22. C. Altona, H. J. Geise, and C. Romers, Tetrahedron 24,13 (1968).

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