Conformation of 17-chloro-16-formyl­androsta-5,16-dien-3β-yl acetate and 17-chloro­androsta-5,16-dien-3β-yl acetate

In the title compounds, C₂₂H₂₉ClO₃, (I), and C₂₁H₂₉ClO₂, (II), respectively, the B rings adopt a half-chair conformation and the D rings adopt an envelope conformation. A twist of the steroid skeleton of both compounds is observed. There is a positional disorder of the acet­oxy group of (II), with the terminal atoms disordered over two positions with near equal occupancy. Quantum-mechanical ab initio calculations using a mol­ecular orbital Hartree–Fock method were performed for the isolated mol­ecules, thus allowing the distinction within the structural features of these two androstane derivatives of which characteristics are intrinsic to the mol­ecules and which are due to packing effects. The skeletal twisting was found to be innate to the mol­ecules, while the acet­oxy disorder is due to packing effects.

S1. Comment

Treatment of 17-oxoandrost-5-en-3β-yl acetate with POCl₃ and dimethylformamide (Vilsmeier reagent) afforded 17-chloro-16-formylandrosta-5,16-dien-3β-yl acetate, (I), as the major and 17-chloroandrosta-5,16-dien-3β-yl acetate, (II), as the minor reaction product (Sciaky & Pallini, 1964; Marson, 1992; Siddiqui et al., 1995). Compound (I) was found to be an important precursor for the synthesis of steroidal inhibitors of cytochrome P450 17α-hydroxylase-C17,20-lyase as potential agents for prostate cancer treatment (Njar et al., 1998; Handratta et al., 2005; Moreira et al., 2007). We report here the molecular structures of (I) and (II) determined by single-crystal X-ray analysis, and compare them with those of the free molecules as given by quantum-mechanical ab initio calculations.

An ORTEPII (Johnson, 1976) plot of (I) is shown in Fig. 1 and a plot of (II) in Fig. 2. The two compounds are very similar: both have acetoxy and chloro substituents at the 3 and 17 positions and compound (I) has an extra formyl group at the 16 position. In both compounds, the A/B junction is quasi-trans and the remaining rings are trans fused. The acetoxy substituents at C3 are in equatorial positions, with angles to the normal (Cremer & Pople, 1975) of ring A of 68.43 (15) and 68.4 (2)°, respectively, for (I) and (II). In compound (II) the substituent is disordered, with atoms O2 and C31 and methyl group C32 occupying two positions with near-equal occupancy. Rings A and C have slightly flattened chair conformations, as shown by the mean values of their torsion angles [52.97 (12)–55.33 (14)°]. The unsaturated ring B adopts a half-chair conformation, with puckering parameters (Cremer & Pople, 1975) Q = 0.474 (3) Å, θ = 52.0 (4)° and ϕ = 210.0 (4)° for (I), and Q = 0.491 (3) Å, θ = 51.5 (3)° and ϕ = 211.0 (5)° for (II).

The five-membered ring D features a double bond at C16—C17 and shows a conformation that can be described as an envelope on C14, with P = 11.3 (3) and τ = 36.0 (2)° [P = 12.0 (4) and τ = 35.7 (2)° for (II)]. The values of the bowing angles, the angle between the least-squares plane of ring A and the least-squares plane that includes the atoms of rings B, C and D, are 23.43 (9) for (I) and 21.35 (4)° for (II). The corresponding distances between terminal atoms C3 and C16 are 8.921 (5) and 8.867 (5) Å, and the values for the pseudo torsion angle C19—C10···C13—C18 are 12.9 (5) for (I) and 9.4 (5)° for (II).

We have performed a quantum mechanical calculation of the equilibrium geometry of the free molecule using GAMESS (Schmidt et al., 1993) under conditions described previously (Ramos Silva et al., 2008). By comparing the calculated and experimental structural parameters it is possible to infer whether the molecular conformation is intrinsic to the free steroid molecule or is rather due to intermolecular interactions. The calculations reproduce the twist of the molecules as measured by the pseudo torsion angle C19—C10···C13—C18, slightly decreased for (I) at 10.2°, and slightly increased for (II) at 9.9°. Such twists are therefore intrinsic to the molecule and not a packing effect, as confirmed by previous studies (Ramos Silva et al., 2008; Pinto et al., 2008; Paixão et al., 2004). For compound (I), the geometry of the isolated molecule that corresponds to the energy minimum is quite similar to that observed in the solid state. Larger differences are found for the head and tail groups; the calculated C3—O1—C31—O2 torsion angle is 0.6° [observed 1.5 (4)°] and the calculated C15—C16—C161—O3 torsion angle is -1.7° [observed 3.2 (5)°].

There are no hydrogen bonds joining the molecules [of (I)?]. They pack in such a way that the terminal acetoxy/formyl groups come close, with the shortest intermolecular contact being O3···O1ⁱ at a distance of 3.440 (3)Å [symmetry code: (i) 3/2 - x, 1 - y, -1/2 + z]. Without the formyl substituent, the molecules of (II) pack in a different way. They assemble head to tail, with the shortest intermolecular contact being C14···O2'ⁱⁱ at a distance of 3.311 (9) Å [symmetry code: (ii) -x + 1, -1/2 + y, 1/2 - z].

Packing effects have a significant impact on the conformation of the molecule of (II), as seen by comparison with the calculation for the isolated molecule. The minimum energy for compound (II) is achieved with the acetoxy group in-plane with atoms C3 and C4, and C3—O1—C31—O2 converges to -0.3°, while in the solid state both alternative positions for the acetoxy group result in higher torsion angles [C3—O1—C31—O2 = -8.9 (13) and C3—O1—C31'—O2' = 4.7 (14)°].

S2. Experimental

Details of the synthesis have been previously reported (Siddiqui et al., 1995; Njar et al., 1998; Moreira et al., 2007). Compounds (I) and (II) were each crystallized from a solution in mixture of ethyl acetate and n-hexane [Ratio of solvents?] by slow evaporation.

S3. Refinement

All H atoms were refined as riding on their parent atoms, with C—H = 0.93–0.98 Å and U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C). Atoms O2, C31 and C32 (and their riding H atoms) are disordered over two alternative conformations. The final refined occupancy of the major components was 0.504 (9). The disordered atoms were refined isotropically. The absolute configuration known from the synthesis route was confirmed from the X-ray data.

Computing details

For both compounds, data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of compound (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The molecular structure of compound (II), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. The minor component of the disordered acetoxy group is shown with broken bonds. [Please check added text]

(I) 17-chloro-16-formylandrosta-5,16-dien-3β-yl acetate

Crystal data

C22H29ClO3	F(000) = 808
Mr = 376.90	Dx = 1.253 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 4667 reflections
a = 6.0689 (2) Å	θ = 2.3–18.6°
b = 13.2879 (4) Å	µ = 0.21 mm^−1
c = 24.7664 (8) Å	T = 293 K
V = 1997.24 (11) Å^3	Prism, colourless
Z = 4	0.42 × 0.17 × 0.09 mm

Data collection

Bruker APEX CCD area-detector diffractometer	3757 independent reflections
Radiation source: fine-focus sealed tube	2563 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.084
ϕ and ω scans	θmax = 25.7°, θmin = 1.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	h = −7→7
Tmin = 0.863, Tmax = 0.98	k = −16→16
38455 measured reflections	l = −29→30

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.105	w = 1/[σ^2(Fo^2) + (0.0469P)^2 + 0.1552P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max = 0.001
3757 reflections	Δρmax = 0.14 e Å^−3
238 parameters	Δρmin = −0.23 e Å^−3
0 restraints	Absolute structure: Flack (1983), with 1551 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.02 (10)

Special details

Experimental. Quantum-mechanical calculations of the equilibrium geometry of the free molecules were performed with the computer program GAMESS (Schmidt et al., 1993). A molecular-orbital Roothan Hartree–Fock method was used with an extended 6-31 G(d,p) basis set. Tight conditions for convergence of both the self-consistent field cycles and the maximum density and energy gradients were imposed (10^-5 atomic units).

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
Cl1	0.25370 (14)	0.70059 (8)	0.81619 (3)	0.0985 (3)
C1	0.3556 (4)	0.4315 (2)	1.09415 (10)	0.0544 (7)
H11	0.2592	0.4892	1.0986	0.065*
H12	0.2756	0.3814	1.0735	0.065*
C2	0.4055 (4)	0.3878 (2)	1.15016 (10)	0.0554 (7)
H21	0.4692	0.4397	1.1729	0.067*
H22	0.2697	0.3652	1.1669	0.067*
C3	0.5625 (4)	0.3014 (2)	1.14567 (9)	0.0510 (7)
H3	0.4922	0.2464	1.1257	0.061*
O1	0.6090 (3)	0.26842 (14)	1.20060 (7)	0.0563 (5)
C31	0.6815 (5)	0.1745 (2)	1.20749 (13)	0.0670 (8)
O2	0.7134 (5)	0.11780 (17)	1.17084 (9)	0.0949 (8)
C32	0.7140 (6)	0.1511 (3)	1.26598 (12)	0.0908 (11)
H31	0.6263	0.0937	1.2756	0.136*
H32	0.6699	0.2080	1.2873	0.136*
H33	0.8666	0.1367	1.2726	0.136*
C4	0.7714 (4)	0.3324 (2)	1.11704 (9)	0.0511 (7)
H41	0.8657	0.2741	1.1126	0.061*
H42	0.8498	0.3811	1.1390	0.061*
C5	0.7234 (4)	0.37796 (18)	1.06227 (9)	0.0420 (6)
C6	0.8202 (4)	0.34268 (18)	1.01840 (10)	0.0480 (6)
H6	0.9131	0.2875	1.0224	0.058*
C7	0.7920 (4)	0.38455 (18)	0.96276 (9)	0.0493 (6)
H71	0.7051	0.3379	0.9415	0.059*
H72	0.9355	0.3906	0.9458	0.059*
C8	0.6800 (4)	0.48692 (18)	0.96248 (9)	0.0410 (6)
H8	0.7869	0.5385	0.9730	0.049*
C9	0.4856 (4)	0.48758 (18)	1.00291 (9)	0.0416 (6)
H9	0.3904	0.4315	0.9922	0.050*
C10	0.5582 (4)	0.46448 (18)	1.06133 (9)	0.0418 (6)
C11	0.3424 (4)	0.5825 (2)	0.99809 (11)	0.0583 (8)
H111	0.2093	0.5724	1.0191	0.070*
H112	0.4218	0.6384	1.0141	0.070*
C12	0.2761 (4)	0.6118 (2)	0.94048 (9)	0.0605 (8)
H121	0.1724	0.5629	0.9263	0.073*
H122	0.2045	0.6771	0.9408	0.073*
C13	0.4797 (4)	0.6158 (2)	0.90426 (10)	0.0497 (6)
C14	0.5897 (4)	0.51183 (18)	0.90722 (10)	0.0432 (6)
H14	0.4689	0.4639	0.9018	0.052*
C15	0.7266 (5)	0.50465 (19)	0.85556 (9)	0.0543 (7)
H151	0.8708	0.5349	0.8602	0.065*
H152	0.7439	0.4354	0.8439	0.065*
C16	0.5876 (5)	0.5636 (2)	0.81674 (10)	0.0557 (7)
C161	0.6006 (6)	0.5532 (3)	0.75833 (13)	0.0741 (9)
H161	0.5132	0.5955	0.7374	0.089*
O3	0.7159 (5)	0.4940 (2)	0.73529 (8)	0.0925 (8)
C17	0.4456 (5)	0.6211 (2)	0.84412 (11)	0.0574 (7)
C18	0.6321 (5)	0.7036 (2)	0.91963 (12)	0.0667 (8)
H181	0.5600	0.7662	0.9118	0.100*
H182	0.7662	0.6991	0.8992	0.100*
H183	0.6655	0.7002	0.9575	0.100*
C19	0.6669 (5)	0.55694 (19)	1.08863 (11)	0.0608 (8)
H191	0.5574	0.6077	1.0949	0.091*
H192	0.7797	0.5834	1.0655	0.091*
H193	0.7310	0.5370	1.1224	0.091*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0769 (5)	0.1319 (8)	0.0866 (6)	0.0260 (6)	−0.0113 (5)	0.0407 (5)
C1	0.0399 (14)	0.075 (2)	0.0487 (16)	0.0110 (14)	0.0053 (12)	−0.0010 (14)
C2	0.0464 (15)	0.0729 (19)	0.0470 (16)	0.0047 (15)	0.0063 (12)	−0.0010 (15)
C3	0.0557 (15)	0.0568 (17)	0.0407 (15)	−0.0009 (14)	−0.0013 (13)	−0.0077 (13)
O1	0.0691 (12)	0.0532 (12)	0.0466 (11)	0.0048 (10)	0.0041 (9)	0.0021 (9)
C31	0.0616 (18)	0.062 (2)	0.078 (2)	0.0073 (17)	0.0160 (16)	0.0059 (18)
O2	0.122 (2)	0.0661 (15)	0.0969 (17)	0.0189 (16)	0.0274 (16)	−0.0055 (13)
C32	0.102 (3)	0.090 (2)	0.080 (2)	0.024 (2)	0.013 (2)	0.0322 (18)
C4	0.0464 (14)	0.0600 (17)	0.0469 (14)	0.0071 (14)	0.0004 (13)	−0.0042 (13)
C5	0.0368 (13)	0.0495 (15)	0.0398 (13)	0.0009 (13)	−0.0009 (11)	−0.0025 (11)
C6	0.0455 (14)	0.0468 (16)	0.0517 (16)	0.0069 (12)	0.0005 (12)	−0.0005 (12)
C7	0.0524 (15)	0.0523 (16)	0.0432 (14)	0.0034 (14)	0.0077 (12)	−0.0039 (12)
C8	0.0380 (13)	0.0432 (15)	0.0419 (14)	−0.0017 (12)	−0.0002 (11)	−0.0069 (11)
C9	0.0356 (12)	0.0492 (16)	0.0401 (15)	0.0009 (12)	0.0000 (11)	−0.0045 (12)
C10	0.0371 (13)	0.0485 (16)	0.0399 (14)	0.0048 (12)	−0.0017 (11)	−0.0083 (12)
C11	0.0478 (15)	0.072 (2)	0.0550 (17)	0.0202 (15)	0.0047 (13)	−0.0001 (14)
C12	0.0464 (15)	0.075 (2)	0.0601 (17)	0.0172 (16)	−0.0012 (14)	0.0088 (14)
C13	0.0444 (14)	0.0556 (17)	0.0491 (16)	0.0023 (14)	−0.0047 (12)	0.0030 (13)
C14	0.0410 (13)	0.0495 (16)	0.0392 (14)	−0.0052 (12)	−0.0013 (11)	−0.0028 (12)
C15	0.0569 (16)	0.0600 (17)	0.0461 (15)	−0.0005 (15)	0.0030 (14)	−0.0027 (12)
C16	0.0589 (17)	0.0660 (19)	0.0421 (16)	−0.0132 (15)	−0.0066 (14)	0.0070 (14)
C161	0.079 (2)	0.090 (3)	0.053 (2)	−0.017 (2)	−0.0013 (18)	0.0097 (19)
O3	0.117 (2)	0.1088 (19)	0.0517 (13)	−0.0194 (18)	0.0144 (14)	−0.0061 (12)
C17	0.0476 (15)	0.0644 (19)	0.0603 (18)	−0.0055 (15)	−0.0090 (14)	0.0134 (16)
C18	0.0742 (19)	0.0536 (18)	0.072 (2)	−0.0001 (17)	−0.0086 (16)	−0.0016 (15)
C19	0.0693 (18)	0.0581 (18)	0.0550 (17)	−0.0001 (16)	−0.0091 (15)	−0.0116 (14)

Geometric parameters (Å, º)

Cl1—C17	1.717 (3)	C8—H8	0.9800
C1—C2	1.534 (4)	C9—C11	1.536 (3)
C1—C10	1.538 (3)	C9—C10	1.543 (3)
C1—H11	0.9700	C9—H9	0.9800
C1—H12	0.9700	C10—C19	1.550 (3)
C2—C3	1.497 (4)	C11—C12	1.533 (3)
C2—H21	0.9700	C11—H111	0.9700
C2—H22	0.9700	C11—H112	0.9700
C3—O1	1.457 (3)	C12—C13	1.528 (3)
C3—C4	1.510 (3)	C12—H121	0.9700
C3—H3	0.9800	C12—H122	0.9700
O1—C31	1.335 (3)	C13—C17	1.505 (4)
C31—O2	1.195 (3)	C13—C14	1.536 (3)
C31—C32	1.494 (4)	C13—C18	1.536 (4)
C32—H31	0.9600	C14—C15	1.529 (3)
C32—H32	0.9600	C14—H14	0.9800
C32—H33	0.9600	C15—C16	1.500 (4)
C4—C5	1.514 (3)	C15—H151	0.9700
C4—H41	0.9700	C15—H152	0.9700
C4—H42	0.9700	C16—C17	1.337 (4)
C5—C6	1.321 (3)	C16—C161	1.456 (4)
C5—C10	1.526 (3)	C161—O3	1.197 (4)
C6—C7	1.496 (3)	C161—H161	0.9300
C6—H6	0.9300	C18—H181	0.9600
C7—C8	1.521 (3)	C18—H182	0.9600
C7—H71	0.9700	C18—H183	0.9600
C7—H72	0.9700	C19—H191	0.9600
C8—C14	1.511 (3)	C19—H192	0.9600
C8—C9	1.547 (3)	C19—H193	0.9600
C2—C1—C10	115.3 (2)	C5—C10—C1	107.6 (2)
C2—C1—H11	108.4	C5—C10—C9	110.59 (18)
C10—C1—H11	108.4	C1—C10—C9	108.91 (19)
C2—C1—H12	108.4	C5—C10—C19	108.12 (19)
C10—C1—H12	108.4	C1—C10—C19	109.6 (2)
H11—C1—H12	107.5	C9—C10—C19	111.9 (2)
C3—C2—C1	110.4 (2)	C12—C11—C9	115.4 (2)
C3—C2—H21	109.6	C12—C11—H111	108.4
C1—C2—H21	109.6	C9—C11—H111	108.4
C3—C2—H22	109.6	C12—C11—H112	108.4
C1—C2—H22	109.6	C9—C11—H112	108.4
H21—C2—H22	108.1	H111—C11—H112	107.5
O1—C3—C2	106.54 (19)	C13—C12—C11	110.1 (2)
O1—C3—C4	111.0 (2)	C13—C12—H121	109.6
C2—C3—C4	111.1 (2)	C11—C12—H121	109.6
O1—C3—H3	109.4	C13—C12—H122	109.6
C2—C3—H3	109.4	C11—C12—H122	109.6
C4—C3—H3	109.4	H121—C12—H122	108.2
C31—O1—C3	117.7 (2)	C17—C13—C12	118.1 (2)
O2—C31—O1	123.1 (3)	C17—C13—C14	98.6 (2)
O2—C31—C32	125.7 (3)	C12—C13—C14	107.0 (2)
O1—C31—C32	111.2 (3)	C17—C13—C18	107.0 (2)
C31—C32—H31	109.5	C12—C13—C18	111.6 (2)
C31—C32—H32	109.5	C14—C13—C18	114.1 (2)
H31—C32—H32	109.5	C8—C14—C15	123.2 (2)
C31—C32—H33	109.5	C8—C14—C13	113.4 (2)
H31—C32—H33	109.5	C15—C14—C13	104.62 (19)
H32—C32—H33	109.5	C8—C14—H14	104.6
C3—C4—C5	111.6 (2)	C15—C14—H14	104.6
C3—C4—H41	109.3	C13—C14—H14	104.6
C5—C4—H41	109.3	C16—C15—C14	101.4 (2)
C3—C4—H42	109.3	C16—C15—H151	111.5
C5—C4—H42	109.3	C14—C15—H151	111.5
H41—C4—H42	108.0	C16—C15—H152	111.5
C6—C5—C4	120.6 (2)	C14—C15—H152	111.5
C6—C5—C10	123.2 (2)	H151—C15—H152	109.3
C4—C5—C10	116.2 (2)	C17—C16—C161	126.4 (3)
C5—C6—C7	125.1 (2)	C17—C16—C15	109.6 (2)
C5—C6—H6	117.5	C161—C16—C15	123.8 (3)
C7—C6—H6	117.5	O3—C161—C16	124.6 (3)
C6—C7—C8	112.84 (19)	O3—C161—H161	117.7
C6—C7—H71	109.0	C16—C161—H161	117.7
C8—C7—H71	109.0	C16—C17—C13	112.7 (2)
C6—C7—H72	109.0	C16—C17—Cl1	125.8 (2)
C8—C7—H72	109.0	C13—C17—Cl1	121.4 (2)
H71—C7—H72	107.8	C13—C18—H181	109.5
C14—C8—C7	111.24 (19)	C13—C18—H182	109.5
C14—C8—C9	107.97 (18)	H181—C18—H182	109.5
C7—C8—C9	110.06 (19)	C13—C18—H183	109.5
C14—C8—H8	109.2	H181—C18—H183	109.5
C7—C8—H8	109.2	H182—C18—H183	109.5
C9—C8—H8	109.2	C10—C19—H191	109.5
C11—C9—C10	113.4 (2)	C10—C19—H192	109.5
C11—C9—C8	112.7 (2)	H191—C19—H192	109.5
C10—C9—C8	112.83 (18)	C10—C19—H193	109.5
C11—C9—H9	105.7	H191—C19—H193	109.5
C10—C9—H9	105.7	H192—C19—H193	109.5
C8—C9—H9	105.7
C10—C1—C2—C3	−55.6 (3)	C8—C9—C10—C19	77.7 (3)
C1—C2—C3—O1	177.1 (2)	C10—C9—C11—C12	176.9 (2)
C1—C2—C3—C4	56.1 (3)	C8—C9—C11—C12	47.2 (3)
C2—C3—O1—C31	157.8 (2)	C9—C11—C12—C13	−51.3 (3)
C4—C3—O1—C31	−81.1 (3)	C11—C12—C13—C17	167.1 (2)
C3—O1—C31—O2	1.5 (4)	C11—C12—C13—C14	57.2 (3)
C3—O1—C31—C32	−178.0 (3)	C11—C12—C13—C18	−68.3 (3)
O1—C3—C4—C5	−173.50 (19)	C7—C8—C14—C15	−50.8 (3)
C2—C3—C4—C5	−55.2 (3)	C9—C8—C14—C15	−171.6 (2)
C3—C4—C5—C6	−126.4 (3)	C7—C8—C14—C13	−178.5 (2)
C3—C4—C5—C10	53.1 (3)	C9—C8—C14—C13	60.6 (3)
C4—C5—C6—C7	−177.4 (2)	C17—C13—C14—C8	171.4 (2)
C10—C5—C6—C7	3.2 (4)	C12—C13—C14—C8	−65.6 (3)
C5—C6—C7—C8	12.8 (4)	C18—C13—C14—C8	58.4 (3)
C6—C7—C8—C14	−162.0 (2)	C17—C13—C14—C15	34.5 (2)
C6—C7—C8—C9	−42.4 (3)	C12—C13—C14—C15	157.5 (2)
C14—C8—C9—C11	−49.1 (3)	C18—C13—C14—C15	−78.5 (3)
C7—C8—C9—C11	−170.7 (2)	C8—C14—C15—C16	−164.5 (2)
C14—C8—C9—C10	−179.2 (2)	C13—C14—C15—C16	−33.1 (3)
C7—C8—C9—C10	59.2 (3)	C14—C15—C16—C17	18.1 (3)
C6—C5—C10—C1	131.0 (3)	C14—C15—C16—C161	−158.4 (3)
C4—C5—C10—C1	−48.4 (3)	C17—C16—C161—O3	−172.7 (3)
C6—C5—C10—C9	12.2 (3)	C15—C16—C161—O3	3.2 (5)
C4—C5—C10—C9	−167.3 (2)	C161—C16—C17—C13	−179.0 (3)
C6—C5—C10—C19	−110.6 (3)	C15—C16—C17—C13	4.6 (3)
C4—C5—C10—C19	69.9 (3)	C161—C16—C17—Cl1	−3.2 (4)
C2—C1—C10—C5	49.6 (3)	C15—C16—C17—Cl1	−179.6 (2)
C2—C1—C10—C9	169.5 (2)	C12—C13—C17—C16	−139.3 (3)
C2—C1—C10—C19	−67.8 (3)	C14—C13—C17—C16	−24.8 (3)
C11—C9—C10—C5	−172.6 (2)	C18—C13—C17—C16	93.8 (3)
C8—C9—C10—C5	−42.9 (3)	C12—C13—C17—Cl1	44.6 (3)
C11—C9—C10—C1	69.3 (3)	C14—C13—C17—Cl1	159.2 (2)
C8—C9—C10—C1	−161.0 (2)	C18—C13—C17—Cl1	−82.2 (3)
C11—C9—C10—C19	−52.0 (3)

(II) 17-chloro-androsta-5,16-dien-3β-yl acetate

Crystal data

C21H29ClO2	F(000) = 752
Mr = 348.89	Dx = 1.211 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 4499 reflections
a = 6.0271 (2) Å	θ = 2.4–19.2°
b = 15.4064 (6) Å	µ = 0.21 mm^−1
c = 20.6081 (9) Å	T = 293 K
V = 1913.58 (13) Å^3	Prism, colourless
Z = 4	0.36 × 0.13 × 0.09 mm

Data collection

Bruker APEX CCD area-detector diffractometer	3615 independent reflections
Radiation source: fine-focus sealed tube	2487 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.076
ϕ and ω scans	θmax = 25.7°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	h = −7→7
Tmin = 0.861, Tmax = 0.98	k = −18→18
35093 measured reflections	l = −25→25

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.063	H-atom parameters constrained
wR(F^2) = 0.165	w = 1/[σ^2(Fo^2) + (0.0733P)^2 + 0.1121P] where P = (Fo^2 + 2Fc^2)/3
S = 1.26	(Δ/σ)max < 0.001
3615 reflections	Δρmax = 0.42 e Å^−3
219 parameters	Δρmin = −0.25 e Å^−3
0 restraints	Absolute structure: Flack (1983), with 1496 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.14 (13)

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)
Cl1	0.2582 (2)	0.86349 (7)	0.36536 (6)	0.0872 (4)
O1	0.7517 (5)	0.15522 (16)	0.39783 (13)	0.0808 (8)
C1	0.4533 (6)	0.3690 (2)	0.4171 (2)	0.0631 (10)
H11	0.3640	0.3907	0.4528	0.076*
H12	0.3602	0.3681	0.3787	0.076*
C2	0.5249 (7)	0.2760 (3)	0.4327 (2)	0.0707 (11)
H21	0.6037	0.2751	0.4737	0.085*
H22	0.3946	0.2395	0.4369	0.085*
C3	0.6730 (6)	0.2408 (2)	0.37979 (19)	0.0646 (10)
H3	0.5907	0.2376	0.3388	0.078*
O2	0.4771 (13)	0.0950 (5)	0.3462 (4)	0.103 (3)*	0.504 (9)
C31	0.653 (2)	0.0892 (6)	0.3759 (4)	0.069 (3)*	0.504 (9)
C32	0.824 (2)	0.0095 (6)	0.3812 (5)	0.077 (3)*	0.504 (9)
H31	0.7874	−0.0334	0.3492	0.116*	0.504 (9)
H32	0.8142	−0.0158	0.4237	0.116*	0.504 (9)
H33	0.9721	0.0301	0.3739	0.116*	0.504 (9)
O2'	0.6819 (15)	0.1018 (5)	0.3057 (4)	0.128 (4)*	0.496 (9)
C31'	0.7452 (18)	0.0900 (6)	0.3607 (5)	0.064 (2)*	0.496 (9)
C32'	0.744 (2)	0.0036 (6)	0.3942 (5)	0.071 (3)*	0.496 (9)
H31'	0.7978	−0.0402	0.3650	0.106*	0.496 (9)
H32'	0.5955	−0.0104	0.4073	0.106*	0.496 (9)
H33'	0.8383	0.0060	0.4317	0.106*	0.496 (9)
C4	0.8747 (6)	0.2988 (2)	0.3717 (2)	0.0647 (10)
H41	0.9634	0.2967	0.4110	0.078*
H42	0.9649	0.2773	0.3362	0.078*
C5	0.8094 (5)	0.3915 (2)	0.35818 (17)	0.0522 (9)
C6	0.8875 (6)	0.4341 (2)	0.30731 (17)	0.0587 (9)
H6	0.9814	0.4036	0.2797	0.070*
C7	0.8403 (6)	0.5251 (2)	0.29013 (17)	0.0586 (9)
H71	0.7436	0.5263	0.2525	0.070*
H72	0.9780	0.5537	0.2784	0.070*
C8	0.7314 (5)	0.5747 (2)	0.34514 (15)	0.0489 (8)
H8	0.8435	0.5893	0.3778	0.059*
C9	0.5495 (5)	0.5174 (2)	0.37662 (16)	0.0487 (8)
H9	0.4528	0.4991	0.3409	0.058*
C10	0.6468 (5)	0.4324 (2)	0.40545 (16)	0.0485 (8)
C11	0.3987 (6)	0.5665 (2)	0.42431 (18)	0.0613 (10)
H111	0.2720	0.5301	0.4344	0.074*
H112	0.4801	0.5759	0.4643	0.074*
C12	0.3136 (6)	0.6544 (2)	0.39980 (19)	0.0603 (9)
H121	0.2077	0.6453	0.3650	0.072*
H122	0.2385	0.6847	0.4348	0.072*
C13	0.5064 (5)	0.7094 (2)	0.37514 (16)	0.0512 (8)
C14	0.6210 (5)	0.6572 (2)	0.32176 (15)	0.0475 (8)
H14	0.5001	0.6374	0.2936	0.057*
C15	0.7441 (7)	0.7262 (2)	0.28149 (18)	0.0639 (9)
H151	0.8891	0.7390	0.2995	0.077*
H152	0.7600	0.7085	0.2366	0.077*
C16	0.5877 (7)	0.8022 (3)	0.2883 (2)	0.0686 (11)
H16	0.5858	0.8506	0.2613	0.082*
C17	0.4554 (6)	0.7901 (3)	0.33777 (19)	0.0602 (10)
C18	0.6594 (6)	0.7353 (2)	0.43210 (18)	0.0655 (10)
H181	0.7920	0.7617	0.4154	0.098*
H182	0.6978	0.6845	0.4566	0.098*
H183	0.5836	0.7758	0.4597	0.098*
C19	0.7688 (7)	0.4496 (2)	0.47003 (16)	0.0647 (10)
H191	0.8463	0.3981	0.4832	0.097*
H192	0.6629	0.4653	0.5028	0.097*
H193	0.8730	0.4961	0.4643	0.097*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0749 (7)	0.0736 (7)	0.1132 (9)	0.0154 (6)	0.0010 (7)	0.0005 (6)
O1	0.097 (2)	0.0541 (15)	0.0916 (19)	0.0028 (17)	−0.0363 (18)	−0.0016 (14)
C1	0.0428 (19)	0.065 (2)	0.081 (3)	−0.0043 (17)	0.0097 (18)	0.015 (2)
C2	0.054 (2)	0.069 (3)	0.089 (3)	−0.008 (2)	0.002 (2)	0.017 (2)
C3	0.062 (2)	0.061 (2)	0.071 (2)	0.0033 (18)	−0.017 (2)	0.0060 (19)
C4	0.055 (2)	0.069 (2)	0.070 (2)	0.0117 (19)	0.005 (2)	−0.001 (2)
C5	0.0421 (18)	0.060 (2)	0.054 (2)	−0.0020 (15)	0.0009 (16)	−0.0019 (17)
C6	0.052 (2)	0.069 (2)	0.055 (2)	0.0034 (19)	0.0085 (18)	−0.0078 (19)
C7	0.0483 (19)	0.073 (2)	0.055 (2)	−0.0045 (18)	0.0120 (18)	−0.0016 (18)
C8	0.0397 (16)	0.063 (2)	0.0437 (17)	−0.0079 (17)	0.0017 (15)	−0.0031 (15)
C9	0.0351 (16)	0.061 (2)	0.0499 (19)	0.0009 (14)	0.0029 (14)	−0.0026 (17)
C10	0.0356 (15)	0.061 (2)	0.0490 (18)	−0.0028 (15)	0.0043 (15)	0.0026 (16)
C11	0.0450 (19)	0.067 (2)	0.072 (2)	0.0023 (18)	0.0181 (18)	0.006 (2)
C12	0.0440 (19)	0.067 (2)	0.070 (2)	−0.0007 (17)	0.0138 (17)	−0.0011 (19)
C13	0.0431 (18)	0.057 (2)	0.053 (2)	−0.0062 (16)	−0.0008 (17)	−0.0023 (17)
C14	0.0423 (17)	0.056 (2)	0.0441 (18)	−0.0072 (16)	−0.0052 (15)	−0.0001 (16)
C15	0.063 (2)	0.070 (2)	0.059 (2)	−0.009 (2)	0.004 (2)	0.0082 (18)
C16	0.075 (3)	0.064 (3)	0.067 (3)	−0.010 (2)	−0.005 (2)	0.009 (2)
C17	0.052 (2)	0.057 (2)	0.071 (3)	−0.0007 (17)	−0.010 (2)	−0.0067 (19)
C18	0.056 (2)	0.080 (3)	0.060 (2)	0.0017 (19)	−0.0089 (19)	−0.010 (2)
C19	0.058 (2)	0.080 (2)	0.056 (2)	0.007 (2)	0.0002 (19)	−0.0001 (18)

Geometric parameters (Å, º)

Cl1—C17	1.736 (4)	C7—H71	0.9700
O1—C31	1.262 (10)	C7—H72	0.9700
O1—C31'	1.264 (9)	C8—C14	1.513 (5)
O1—C3	1.450 (4)	C8—C9	1.550 (4)
C1—C2	1.530 (5)	C8—H8	0.9800
C1—C10	1.540 (4)	C9—C11	1.538 (4)
C1—H11	0.9700	C9—C10	1.553 (5)
C1—H12	0.9700	C9—H9	0.9800
C2—C3	1.510 (6)	C10—C19	1.544 (5)
C2—H21	0.9700	C11—C12	1.533 (5)
C2—H22	0.9700	C11—H111	0.9700
C3—C4	1.518 (6)	C11—H112	0.9700
C3—H3	0.9800	C12—C13	1.526 (5)
O2—C31	1.228 (11)	C12—H121	0.9700
C31—C32	1.606 (14)	C12—H122	0.9700
C32—H31	0.9600	C13—C17	1.494 (5)
C32—H32	0.9600	C13—C14	1.528 (5)
C32—H33	0.9600	C13—C18	1.545 (5)
O2'—C31'	1.209 (10)	C14—C15	1.539 (4)
C31'—C32'	1.500 (13)	C14—H14	0.9800
C32'—H31'	0.9600	C15—C16	1.510 (5)
C32'—H32'	0.9600	C15—H151	0.9700
C32'—H33'	0.9600	C15—H152	0.9700
C4—C5	1.506 (5)	C16—C17	1.307 (5)
C4—H41	0.9700	C16—H16	0.9300
C4—H42	0.9700	C18—H181	0.9600
C5—C6	1.324 (5)	C18—H182	0.9600
C5—C10	1.519 (5)	C18—H183	0.9600
C6—C7	1.474 (5)	C19—H191	0.9600
C6—H6	0.9300	C19—H192	0.9600
C7—C8	1.517 (5)	C19—H193	0.9600
C31—O1—C3	119.2 (5)	C8—C9—C10	111.9 (2)
C31'—O1—C3	123.9 (5)	C11—C9—H9	105.7
C2—C1—C10	114.4 (3)	C8—C9—H9	105.7
C2—C1—H11	108.7	C10—C9—H9	105.7
C10—C1—H11	108.7	C5—C10—C1	109.0 (3)
C2—C1—H12	108.7	C5—C10—C19	108.5 (3)
C10—C1—H12	108.7	C1—C10—C19	109.6 (3)
H11—C1—H12	107.6	C5—C10—C9	110.4 (3)
C3—C2—C1	110.6 (3)	C1—C10—C9	108.0 (3)
C3—C2—H21	109.5	C19—C10—C9	111.4 (3)
C1—C2—H21	109.5	C12—C11—C9	115.0 (3)
C3—C2—H22	109.5	C12—C11—H111	108.5
C1—C2—H22	109.5	C9—C11—H111	108.5
H21—C2—H22	108.1	C12—C11—H112	108.5
O1—C3—C2	109.6 (3)	C9—C11—H112	108.5
O1—C3—C4	107.5 (3)	H111—C11—H112	107.5
C2—C3—C4	110.0 (3)	C13—C12—C11	110.2 (3)
O1—C3—H3	109.9	C13—C12—H121	109.6
C2—C3—H3	109.9	C11—C12—H121	109.6
C4—C3—H3	109.9	C13—C12—H122	109.6
O2—C31—O1	121.8 (8)	C11—C12—H122	109.6
O2—C31—C32	130.0 (8)	H121—C12—H122	108.1
O1—C31—C32	106.9 (9)	C17—C13—C12	118.5 (3)
O2'—C31'—O1	117.2 (8)	C17—C13—C14	99.2 (3)
O2'—C31'—C32'	124.3 (8)	C12—C13—C14	106.9 (3)
O1—C31'—C32'	115.3 (8)	C17—C13—C18	107.5 (3)
C31'—C32'—H31'	109.5	C12—C13—C18	110.2 (3)
C31'—C32'—H32'	109.5	C14—C13—C18	114.4 (3)
H31'—C32'—H32'	109.5	C8—C14—C13	114.3 (3)
C31'—C32'—H33'	109.5	C8—C14—C15	122.7 (3)
H31'—C32'—H33'	109.5	C13—C14—C15	104.0 (3)
H32'—C32'—H33'	109.5	C8—C14—H14	104.7
C5—C4—C3	111.6 (3)	C13—C14—H14	104.7
C5—C4—H41	109.3	C15—C14—H14	104.7
C3—C4—H41	109.3	C16—C15—C14	100.6 (3)
C5—C4—H42	109.3	C16—C15—H151	111.6
C3—C4—H42	109.3	C14—C15—H151	111.6
H41—C4—H42	108.0	C16—C15—H152	111.6
C6—C5—C4	121.6 (3)	C14—C15—H152	111.6
C6—C5—C10	122.1 (3)	H151—C15—H152	109.4
C4—C5—C10	116.3 (3)	C17—C16—C15	110.0 (3)
C5—C6—C7	126.4 (3)	C17—C16—H16	125.0
C5—C6—H6	116.8	C15—C16—H16	125.0
C7—C6—H6	116.8	C16—C17—C13	113.3 (3)
C6—C7—C8	112.6 (3)	C16—C17—Cl1	125.4 (3)
C6—C7—H71	109.1	C13—C17—Cl1	120.9 (3)
C8—C7—H71	109.1	C13—C18—H181	109.5
C6—C7—H72	109.1	C13—C18—H182	109.5
C8—C7—H72	109.1	H181—C18—H182	109.5
H71—C7—H72	107.8	C13—C18—H183	109.5
C14—C8—C7	112.1 (3)	H181—C18—H183	109.5
C14—C8—C9	107.5 (3)	H182—C18—H183	109.5
C7—C8—C9	109.4 (3)	C10—C19—H191	109.5
C14—C8—H8	109.3	C10—C19—H192	109.5
C7—C8—H8	109.3	H191—C19—H192	109.5
C9—C8—H8	109.3	C10—C19—H193	109.5
C11—C9—C8	113.9 (3)	H191—C19—H193	109.5
C11—C9—C10	113.2 (3)	H192—C19—H193	109.5
C10—C1—C2—C3	−55.9 (5)	C2—C1—C10—C19	−70.1 (4)
C31—O1—C3—C2	97.4 (7)	C2—C1—C10—C9	168.4 (3)
C31'—O1—C3—C2	131.4 (7)	C11—C9—C10—C5	−175.0 (3)
C31—O1—C3—C4	−143.1 (7)	C8—C9—C10—C5	−44.7 (4)
C31'—O1—C3—C4	−109.1 (7)	C11—C9—C10—C1	65.9 (4)
C1—C2—C3—O1	175.8 (3)	C8—C9—C10—C1	−163.7 (3)
C1—C2—C3—C4	57.8 (4)	C11—C9—C10—C19	−54.4 (4)
C31'—O1—C31—O2	−117.0 (18)	C8—C9—C10—C19	75.9 (3)
C3—O1—C31—O2	−8.9 (13)	C8—C9—C11—C12	46.1 (4)
C31'—O1—C31—C32	51.1 (13)	C10—C9—C11—C12	175.4 (3)
C3—O1—C31—C32	159.2 (6)	C9—C11—C12—C13	−51.0 (4)
C31—O1—C31'—O2'	94.8 (16)	C11—C12—C13—C17	168.5 (3)
C3—O1—C31'—O2'	4.7 (14)	C11—C12—C13—C14	57.7 (4)
C31—O1—C31'—C32'	−65.9 (15)	C11—C12—C13—C18	−67.2 (4)
C3—O1—C31'—C32'	−156.0 (8)	C7—C8—C14—C13	179.4 (3)
O1—C3—C4—C5	−175.4 (3)	C9—C8—C14—C13	59.2 (3)
C2—C3—C4—C5	−56.1 (4)	C7—C8—C14—C15	−53.3 (4)
C3—C4—C5—C6	−126.5 (4)	C9—C8—C14—C15	−173.5 (3)
C3—C4—C5—C10	52.6 (4)	C17—C13—C14—C8	170.6 (3)
C4—C5—C6—C7	−178.3 (3)	C12—C13—C14—C8	−65.8 (3)
C10—C5—C6—C7	2.7 (5)	C18—C13—C14—C8	56.5 (4)
C5—C6—C7—C8	13.2 (5)	C17—C13—C14—C15	34.2 (3)
C6—C7—C8—C14	−162.5 (3)	C12—C13—C14—C15	157.9 (3)
C6—C7—C8—C9	−43.4 (4)	C18—C13—C14—C15	−79.8 (3)
C14—C8—C9—C11	−47.3 (4)	C8—C14—C15—C16	−164.3 (3)
C7—C8—C9—C11	−169.2 (3)	C13—C14—C15—C16	−32.7 (3)
C14—C8—C9—C10	−177.3 (3)	C14—C15—C16—C17	18.4 (4)
C7—C8—C9—C10	60.8 (3)	C15—C16—C17—C13	4.0 (4)
C6—C5—C10—C1	131.9 (3)	C15—C16—C17—Cl1	176.9 (3)
C4—C5—C10—C1	−47.2 (4)	C12—C13—C17—C16	−139.6 (4)
C6—C5—C10—C19	−108.9 (4)	C14—C13—C17—C16	−24.6 (4)
C4—C5—C10—C19	72.1 (4)	C18—C13—C17—C16	94.7 (4)
C6—C5—C10—C9	13.5 (4)	C12—C13—C17—Cl1	47.1 (4)
C4—C5—C10—C9	−165.6 (3)	C14—C13—C17—Cl1	162.1 (2)
C2—C1—C10—C5	48.5 (4)	C18—C13—C17—Cl1	−78.5 (3)