(4aSR,7SR,9aSR)-7-tert-Butyl-9a-methyl-5,5-dioxo-1,2,4a,9a-tetra­hydro-8-oxa-5λ⁶-thia­benzocyclo­heptan-9-one

The title compound, C₁₄H₂₂O₄S, crystallizes as a non-merohedral twin with a twinning ratio close to 1:1. The six-membered ring exhibits a half-chair conformation, and the seven-membered ring displays an irregular chair-like conformation.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.049
• wR factor = 0.119
• Data-to-parameter ratio = 67.3

checkCIF/PLATON results

No syntax errors found



Alert level A
REFLT03_ALERT_3_A  Reflection count > 15% excess reflns - sys abs data present?
           From the CIF: _diffrn_reflns_theta_max           28.28
           From the CIF: _diffrn_reflns_theta_full          28.28
           From the CIF: _reflns_number_total              11919
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         3517
           Completeness (_total/calc)            338.90%

Author Response: The crystal under investigation was pseudo-merohedrally twinned with a BASF value of 0.4675(6) and both components were used for the hklf 5 refinement, resulting in a larger than expected number of total reflections.

PLAT021_ALERT_1_A Ratio Unique / Expected Reflections too High ...       3.39

Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    S5     -   O1      ..       6.07 su

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 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

---

S1. Comment

The background to this study is described in the first paper of this series (Zeller et al., 2006).

Compound (II) crystallizes in the triclinic space group P1 with Z = 2 as a racemic mixture of both enantiomers (Fig. 1). The crystal under investigation was found to be non-merohedrally twinned with two components of similar distribution. The data were integrated and the structure was solved and refined using commercial software as described in the Experimental section. The final BASF factor was found to be 0.4675 (6). Similar to four related endo-cycloadducts described previously (Zeller et al., 2004a,b,c,d), the six-membered ring of (II) exhibits the half-chair conformation expected for cyclohexenes. The angles at the unsaturated C atoms are 124.3 (1)° for C4—C3—C2 and 123.5 (1)° for C3—C4—C4A (Fig. 1).

The seven-membered ring displays an irregular chair-like conformation. The sterically demanding tert-butyl group on C7 is located in a pseudo-equatorial position. All intermolecular contacts in (II) are weak, the most pronounced being 3.465 (1) Å for O2···C13(−x, 1 − y, 1 − z). All bond lengths and angles are within their expected ranges.

S2. Experimental

The title compound was synthesized as described by Chumachenko et al. (2005) as a mixture of the exo- and two endo-cycloadducts, viz. (I), (II) and (III), in a ratio of 12/100/4, as established by ¹H NMR of the crude reaction product. The title compound, (II), was isolated from the mixture by selective crystallization from ethyl acetate/hexanes (1:3 v/v) to yield crystals suitable for X-ray structural analysis. [The single-crystal structure of (I) is described in the previous article of this series (Zeller et al., 2006).]

S3. Refinement

The crystal under investigation was found to be non-merohedrally twinned. Two components were identified using GEMINI (Bruker, 1999) and both components were simultaniously integrated using SAINT-Plus (Bruker, 2003). The twin relationship was found to be described by the matrix (1.00039, 0.00139, −0.00035; −0.68441, −1.00009, 0.00096; −0.02404, −0.00039, −1.00027). The data set under investigation had 5380 identified reflections associated with component 1 only, 5367 reflections with component 2 only and 296 are belonging to both components. I/σ for the first component was 13.4 and 12.4 for the second. I/σ for overlapping reflections was 18.7. The data set was corrected for absorption using TWINABS (Bruker, 2003), which was also used to create both an HKLF 4 as well as an HKLF 5 format file. The HKLF 4 format file (with the non-overlapping reflections of component 1 only) was used to establish the space group and solve the structure. The HKLF 5 format file was used for the refinement of the structure; the twin ratio (BASF factor) refined to 0.4675 (6). All H atoms were positioned geometrically (C—H = 0.95–1.00 Å). They were refined with isotropic displacement parameters of 1.5 (methyl) or 1.2 (all others) times that of the equivalent isotropic displacement parameter of the adjacent C atom. Methyl H atoms were allowed to rotate to best fit the experimental data. The s.u. values of the cell parameters are taken from the software, recognizing that the values are unreasonably small (Herbstein, 2000).

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT-Plus (Bruker, 2003); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids.

(4aSR,7SR,9aSR)-7-tert-Butyl-9a-methyl-5,5-dioxo-1,2,4a,9a-tetrahydro-8-oxa- 5λ⁶-thiabenzocycloheptan-9-one

Crystal data

C14H22O4S	Z = 2
Mr = 286.38	F(000) = 308
Triclinic, P1	Dx = 1.345 Mg m^−3
a = 5.6949 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 11.1309 (10) Å	Cell parameters from 6500 reflections
c = 12.3085 (11) Å	θ = 3.2–30.6°
α = 112.539 (2)°	µ = 0.24 mm^−1
β = 90.278 (2)°	T = 100 K
γ = 100.160 (2)°	Block, colourless
V = 707.07 (11) Å^3	0.29 × 0.20 × 0.18 mm

Data collection

Bruker SMART APEX CCD diffractometer	11919 independent reflections
Radiation source: fine-focus sealed tube	11372 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.000
ω scans	θmax = 28.3°, θmin = 1.8°
Absorption correction: multi-scan (TWINABS in SAINT-Plus; Bruker, 2003)	h = −7→7
Tmin = 0.870, Tmax = 0.96	k = −14→14
11949 measured reflections	l = −16→16

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.119	H-atom parameters constrained
S = 1.16	w = 1/[σ^2(Fo^2) + (0.0415P)^2 + 0.3942P] where P = (Fo^2 + 2Fc^2)/3
11919 reflections	(Δ/σ)max < 0.001
177 parameters	Δρmax = 0.57 e Å^−3
0 restraints	Δρmin = −0.39 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	0.5899 (2)	0.79692 (11)	0.24787 (10)	0.0175 (2)
H1A	0.6928	0.7904	0.3097	0.021*
H1B	0.6815	0.7835	0.1774	0.021*
O1	0.58397 (14)	0.64822 (8)	0.42340 (7)	0.02023 (18)
C2	0.5279 (2)	0.93488 (11)	0.29225 (10)	0.0206 (2)
H2A	0.6738	1.0020	0.3309	0.025*
H2B	0.4711	0.9518	0.2242	0.025*
O2	0.23163 (15)	0.69741 (8)	0.53791 (7)	0.02208 (19)
C3	0.3392 (2)	0.94932 (11)	0.37784 (10)	0.0197 (2)
H3	0.3137	1.0362	0.4230	0.024*
O3	0.62698 (15)	0.52763 (8)	0.14649 (7)	0.02197 (18)
C4	0.2049 (2)	0.84889 (11)	0.39487 (10)	0.0177 (2)
H4	0.0946	0.8681	0.4540	0.021*
C4A	0.21794 (19)	0.70603 (11)	0.32544 (9)	0.0144 (2)
H4A	0.0507	0.6570	0.2954	0.017*
S5	0.32699 (5)	0.63747 (3)	0.42553 (2)	0.01507 (7)
C6	0.1931 (2)	0.46497 (10)	0.36741 (9)	0.0171 (2)
H6A	0.2306	0.4264	0.4242	0.020*
H6B	0.0171	0.4556	0.3590	0.020*
C7	0.27879 (19)	0.38690 (10)	0.24789 (9)	0.0148 (2)
H7	0.4534	0.3874	0.2578	0.018*
O8	0.24300 (14)	0.45871 (7)	0.17398 (6)	0.01538 (16)
C9	0.4354 (2)	0.55294 (11)	0.17472 (9)	0.0156 (2)
C9A	0.36523 (19)	0.68776 (10)	0.21616 (9)	0.0143 (2)
C10	0.1434 (2)	0.24316 (11)	0.18638 (10)	0.0157 (2)
C11	0.1893 (2)	0.16651 (11)	0.26202 (11)	0.0204 (2)
H11A	0.1190	0.0724	0.2198	0.031*
H11B	0.1161	0.2014	0.3369	0.031*
H11C	0.3621	0.1767	0.2777	0.031*
C12	0.2411 (2)	0.18335 (11)	0.06519 (10)	0.0204 (2)
H12A	0.4145	0.1906	0.0754	0.031*
H12B	0.2068	0.2315	0.0168	0.031*
H12C	0.1645	0.0898	0.0259	0.031*
C13	−0.1261 (2)	0.23669 (11)	0.16971 (10)	0.0183 (2)
H13A	−0.1532	0.2980	0.1334	0.027*
H13B	−0.1936	0.2617	0.2466	0.027*
H13C	−0.2037	0.1462	0.1185	0.027*
C14	0.2036 (2)	0.68826 (11)	0.11570 (10)	0.0187 (2)
H14A	0.2933	0.6751	0.0456	0.028*
H14B	0.1513	0.7735	0.1406	0.028*
H14C	0.0634	0.6165	0.0970	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0165 (5)	0.0182 (5)	0.0192 (5)	0.0021 (4)	0.0023 (4)	0.0096 (4)
O1	0.0200 (4)	0.0217 (4)	0.0199 (4)	0.0017 (3)	−0.0029 (3)	0.0101 (3)
C2	0.0240 (6)	0.0170 (5)	0.0208 (6)	0.0019 (5)	0.0014 (5)	0.0084 (5)
O2	0.0301 (5)	0.0205 (4)	0.0131 (4)	0.0015 (4)	0.0031 (3)	0.0053 (3)
C3	0.0242 (6)	0.0166 (5)	0.0172 (5)	0.0067 (5)	−0.0017 (5)	0.0043 (4)
O3	0.0202 (4)	0.0213 (4)	0.0268 (4)	0.0070 (3)	0.0084 (4)	0.0106 (4)
C4	0.0188 (5)	0.0194 (5)	0.0145 (5)	0.0075 (5)	0.0009 (4)	0.0045 (4)
C4A	0.0148 (5)	0.0174 (5)	0.0122 (5)	0.0037 (4)	0.0010 (4)	0.0068 (4)
S5	0.01788 (13)	0.01539 (13)	0.01137 (12)	0.00068 (10)	−0.00038 (10)	0.00569 (10)
C6	0.0209 (6)	0.0135 (5)	0.0155 (5)	−0.0014 (4)	−0.0002 (4)	0.0064 (4)
C7	0.0151 (5)	0.0164 (5)	0.0153 (5)	0.0035 (4)	0.0000 (4)	0.0085 (4)
O8	0.0166 (4)	0.0162 (4)	0.0147 (4)	0.0023 (3)	0.0012 (3)	0.0080 (3)
C9	0.0181 (5)	0.0179 (5)	0.0116 (5)	0.0029 (4)	0.0014 (4)	0.0066 (4)
C9A	0.0156 (5)	0.0156 (5)	0.0129 (5)	0.0036 (4)	0.0022 (4)	0.0067 (4)
C10	0.0159 (5)	0.0139 (5)	0.0169 (5)	0.0024 (4)	0.0003 (4)	0.0058 (4)
C11	0.0200 (6)	0.0172 (5)	0.0260 (6)	0.0040 (4)	0.0005 (5)	0.0105 (5)
C12	0.0171 (5)	0.0181 (5)	0.0211 (6)	0.0020 (4)	0.0024 (4)	0.0029 (5)
C13	0.0157 (5)	0.0192 (5)	0.0188 (5)	0.0027 (4)	0.0014 (4)	0.0064 (4)
C14	0.0217 (6)	0.0208 (6)	0.0147 (5)	0.0048 (5)	0.0005 (4)	0.0079 (4)

Geometric parameters (Å, º)

C1—C2	1.5270 (16)	C7—O8	1.4565 (12)
C1—C9A	1.5327 (15)	C7—C10	1.5356 (15)
C1—H1A	0.9900	C7—H7	1.0000
C1—H1B	0.9900	O8—C9	1.3738 (13)
O1—S5	1.4484 (8)	C9—C9A	1.5160 (15)
C2—C3	1.4943 (16)	C9A—C14	1.5401 (15)
C2—H2A	0.9900	C10—C11	1.5324 (15)
C2—H2B	0.9900	C10—C13	1.5327 (15)
O2—S5	1.4426 (8)	C10—C12	1.5347 (15)
C3—C4	1.3260 (16)	C11—H11A	0.9800
C3—H3	0.9500	C11—H11B	0.9800
O3—C9	1.1950 (14)	C11—H11C	0.9800
C4—C4A	1.5049 (15)	C12—H12A	0.9800
C4—H4	0.9500	C12—H12B	0.9800
C4A—C9A	1.5542 (14)	C12—H12C	0.9800
C4A—S5	1.8347 (11)	C13—H13A	0.9800
C4A—H4A	1.0000	C13—H13B	0.9800
S5—C6	1.7902 (11)	C13—H13C	0.9800
C6—C7	1.5276 (15)	C14—H14A	0.9800
C6—H6A	0.9900	C14—H14B	0.9800
C6—H6B	0.9900	C14—H14C	0.9800
C2—C1—C9A	111.80 (9)	C10—C7—H7	109.2
C2—C1—H1A	109.3	C9—O8—C7	115.39 (8)
C9A—C1—H1A	109.3	O3—C9—O8	122.90 (10)
C2—C1—H1B	109.3	O3—C9—C9A	127.11 (10)
C9A—C1—H1B	109.3	O8—C9—C9A	109.99 (9)
H1A—C1—H1B	107.9	C9—C9A—C1	109.98 (9)
C3—C2—C1	111.98 (9)	C9—C9A—C14	107.43 (9)
C3—C2—H2A	109.2	C1—C9A—C14	111.71 (9)
C1—C2—H2A	109.2	C9—C9A—C4A	108.66 (8)
C3—C2—H2B	109.2	C1—C9A—C4A	110.41 (9)
C1—C2—H2B	109.2	C14—C9A—C4A	108.56 (9)
H2A—C2—H2B	107.9	C11—C10—C13	109.72 (9)
C4—C3—C2	124.29 (11)	C11—C10—C12	110.20 (9)
C4—C3—H3	117.9	C13—C10—C12	109.29 (9)
C2—C3—H3	117.9	C11—C10—C7	108.44 (9)
C3—C4—C4A	123.45 (10)	C13—C10—C7	111.37 (9)
C3—C4—H4	118.3	C12—C10—C7	107.80 (9)
C4A—C4—H4	118.3	C10—C11—H11A	109.5
C4—C4A—C9A	112.39 (9)	C10—C11—H11B	109.5
C4—C4A—S5	108.89 (7)	H11A—C11—H11B	109.5
C9A—C4A—S5	113.65 (7)	C10—C11—H11C	109.5
C4—C4A—H4A	107.2	H11A—C11—H11C	109.5
C9A—C4A—H4A	107.2	H11B—C11—H11C	109.5
S5—C4A—H4A	107.2	C10—C12—H12A	109.5
O2—S5—O1	117.93 (5)	C10—C12—H12B	109.5
O2—S5—C6	106.80 (5)	H12A—C12—H12B	109.5
O1—S5—C6	107.89 (5)	C10—C12—H12C	109.5
O2—S5—C4A	107.59 (5)	H12A—C12—H12C	109.5
O1—S5—C4A	109.71 (5)	H12B—C12—H12C	109.5
C6—S5—C4A	106.31 (5)	C10—C13—H13A	109.5
C7—C6—S5	113.09 (7)	C10—C13—H13B	109.5
C7—C6—H6A	109.0	H13A—C13—H13B	109.5
S5—C6—H6A	109.0	C10—C13—H13C	109.5
C7—C6—H6B	109.0	H13A—C13—H13C	109.5
S5—C6—H6B	109.0	H13B—C13—H13C	109.5
H6A—C6—H6B	107.8	C9A—C14—H14A	109.5
O8—C7—C6	105.45 (8)	C9A—C14—H14B	109.5
O8—C7—C10	108.56 (8)	H14A—C14—H14B	109.5
C6—C7—C10	114.95 (9)	C9A—C14—H14C	109.5
O8—C7—H7	109.2	H14A—C14—H14C	109.5
C6—C7—H7	109.2	H14B—C14—H14C	109.5
C9A—C1—C2—C3	44.27 (13)	O8—C9—C9A—C1	165.31 (8)
C1—C2—C3—C4	−13.48 (16)	O3—C9—C9A—C14	107.37 (13)
C2—C3—C4—C4A	−2.99 (18)	O8—C9—C9A—C14	−72.91 (10)
C3—C4—C4A—C9A	−11.74 (15)	O3—C9—C9A—C4A	−135.36 (11)
C3—C4—C4A—S5	115.10 (11)	O8—C9—C9A—C4A	44.35 (11)
C4—C4A—S5—O2	35.29 (9)	C2—C1—C9A—C9	−178.99 (9)
C9A—C4A—S5—O2	161.40 (7)	C2—C1—C9A—C14	61.82 (12)
C4—C4A—S5—O1	−94.17 (8)	C2—C1—C9A—C4A	−59.09 (12)
C9A—C4A—S5—O1	31.94 (9)	C4—C4A—C9A—C9	162.38 (9)
C4—C4A—S5—C6	149.42 (8)	S5—C4A—C9A—C9	38.13 (11)
C9A—C4A—S5—C6	−84.47 (8)	C4—C4A—C9A—C1	41.69 (12)
O2—S5—C6—C7	−179.48 (8)	S5—C4A—C9A—C1	−82.56 (10)
O1—S5—C6—C7	−51.78 (9)	C4—C4A—C9A—C14	−81.08 (11)
C4A—S5—C6—C7	65.85 (9)	S5—C4A—C9A—C14	154.67 (7)
S5—C6—C7—O8	−52.20 (10)	O8—C7—C10—C11	177.85 (8)
S5—C6—C7—C10	−171.72 (8)	C6—C7—C10—C11	−64.37 (12)
C6—C7—O8—C9	91.56 (10)	O8—C7—C10—C13	−61.33 (11)
C10—C7—O8—C9	−144.77 (9)	C6—C7—C10—C13	56.45 (12)
C7—O8—C9—O3	58.59 (14)	O8—C7—C10—C12	58.55 (11)
C7—O8—C9—C9A	−121.14 (9)	C6—C7—C10—C12	176.33 (9)
O3—C9—C9A—C1	−14.41 (15)