Methyl 2-hydroxy-2-[5'-hydroxy-5'-(1-hydroxy-1-methyl­ethyl)-5,2'-di­methyl­per­hydro-2,2'-bi­furan­yl-5-yl]­acetate

The relative configuration was determined for the title compound, C₁₆H₂₈O₇, which was obtained as a mixture of epimers. There are both intra- and intermolecular hydrogen bonds, the latter forming dimers around the crystallographic centres of inversion.

S1. Comment

The title molecule, (I), is involved in both intra- and intermolecular hydrogen bonding. The intramolecular hydrogen bonds are O3—H03···O6 and O7—H07···O5. Both have donor–acceptor distances of less than 2.73 Å, but the O3–H03···O6 angle of 166 (2)° suggests it is the stronger of the two.

The intermolecular hydrogen bonds are bifurcated at H06, i.e. O6—H06···O2 and O6–H06···O3. These link pairs of molecules to from dimers situated around the crystallographic centres of inversion, and the action of these centres on the chiral molecule means they are enantiomerically related.

S2. Experimental

Oxidation of (E,E)-methyl farnesoate by potassium permanganate afforded a mixture of epimeric lactols in a ratio of 6:1. Crystallization from an ether–hexane mixture afforded X-ray quality crystals of the racemate (m.p. 353–356 K), confirming the proposed stereochemical outcome of the oxidative cyclization reaction. We cannot tell if (I) is the major epimer as the two epimers may interconvert via the ring-open form in solution. Crystallization from an ether–hexane mixture afforded X-ray quality crystals of the racemate, confirming the proposed stereochemical outcome of the oxidative cyclization reaction (Brown et al., 2000).

S3. Refinement

The completeness for θ_max = 25.03° was 93.6%, which was slightly lower than the requirement (>95%). The H-atom positions were located from the difference map and fully refined. The bond-length ranges were 0.94 (3)–1.04 (3) Å for C—H and 0.87 (3)–0.88 (2) Å for O—H.

Computing details

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); cell refinement: DENZO and COLLECT; data reduction: DENZO, COLLECT (Hooft, 1998) and maXus (Mackay et al., 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: WinGX (Farrugia, 1998).

(I)

Crystal data

C16H28O7	F(000) = 720
Mr = 332.38	Dx = 1.264 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.5615 (2) Å	Cell parameters from 11814 reflections
b = 11.1023 (4) Å	θ = 3.2–25.0°
c = 20.9017 (5) Å	µ = 0.10 mm^−1
β = 95.302 (2)°	T = 150 K
V = 1747.19 (9) Å^3	Block, colourless
Z = 4	0.4 × 0.4 × 0.3 mm

Data collection

Nonius Kappa CCD area detector diffractometer	2392 reflections with I > 2σ(I)
Radiation source: Nonius FR591 rotating anode	Rint = 0.026
Φ and ω scans to fill Ewald sphere	θmax = 25.0°, θmin = 3.0°
Absorption correction: empirical (using intensity measurements) (SORTAV; Blessing, 1997)	h = −9→8
Tmin = 0.962, Tmax = 0.971	k = −13→13
5490 measured reflections	l = −23→24
2876 independent reflections

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0459P)^2 + 0.5111P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.038	(Δ/σ)max = 0.002
wR(F^2) = 0.100	Δρmax = 0.22 e Å^−3
S = 1.04	Δρmin = −0.21 e Å^−3
2876 reflections	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
321 parameters	Extinction coefficient: 0.016 (3)
0 restraints

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	−0.1978 (2)	1.1799 (2)	0.06154 (9)	0.0327 (4)
C2	0.09649 (19)	1.11322 (15)	0.05546 (7)	0.0230 (4)
C3	0.25453 (19)	1.05047 (15)	0.09094 (7)	0.0220 (4)
C4	0.33612 (18)	1.12402 (14)	0.14986 (7)	0.0215 (4)
C5	0.3581 (2)	1.25525 (16)	0.13215 (9)	0.0300 (4)
C6	0.2377 (2)	1.10448 (15)	0.20985 (7)	0.0238 (4)
C7	0.3249 (2)	0.99189 (16)	0.23995 (7)	0.0246 (4)
C8	0.51785 (19)	1.00672 (14)	0.22536 (7)	0.0216 (4)
C9	0.62172 (19)	0.89076 (14)	0.21957 (7)	0.0203 (4)
C10	0.6403 (2)	0.82591 (16)	0.28399 (8)	0.0247 (4)
C11	0.8022 (2)	0.90886 (15)	0.19298 (8)	0.0253 (4)
C12	0.8227 (2)	0.79475 (16)	0.15384 (8)	0.0283 (4)
C13	0.6329 (2)	0.77072 (15)	0.12543 (7)	0.0260 (4)
C14	0.5803 (2)	0.63832 (17)	0.11301 (8)	0.0328 (4)
C15	0.3874 (3)	0.6287 (2)	0.08487 (11)	0.0465 (5)
C16	0.7058 (4)	0.5775 (2)	0.07054 (11)	0.0526 (6)
O1	−0.04044 (13)	1.11962 (11)	0.09095 (5)	0.0269 (3)
O2	0.09376 (14)	1.15358 (13)	0.00188 (5)	0.0354 (3)
O3	0.37779 (15)	1.03625 (12)	0.04555 (5)	0.0308 (3)
O4	0.51060 (13)	1.07433 (10)	0.16670 (5)	0.0241 (3)
O5	0.52321 (13)	0.81350 (9)	0.17252 (5)	0.0212 (3)
O6	0.58844 (16)	0.83906 (12)	0.06898 (5)	0.0332 (3)
O7	0.60026 (17)	0.57556 (12)	0.17325 (6)	0.0341 (3)
H1A	−0.283 (3)	1.176 (2)	0.0941 (11)	0.051 (6)*
H1B	−0.165 (3)	1.263 (3)	0.0505 (11)	0.057 (7)*
H1C	−0.239 (2)	1.1406 (19)	0.0226 (10)	0.035 (5)*
H3	0.214 (2)	0.9713 (17)	0.1056 (8)	0.020 (4)*
H03	0.452 (3)	0.978 (2)	0.0590 (11)	0.051 (6)*
H5A	0.429 (3)	1.2987 (19)	0.1652 (10)	0.039 (5)*
H5B	0.416 (2)	1.2615 (19)	0.0918 (9)	0.036 (5)*
H5C	0.242 (2)	1.2966 (18)	0.1249 (8)	0.031 (5)*
H06	0.675 (3)	0.845 (3)	0.0445 (13)	0.072 (8)*
H6A	0.257 (2)	1.1747 (19)	0.2377 (9)	0.035 (5)*
H6B	0.107 (2)	1.0966 (17)	0.1985 (8)	0.029 (4)*
H07	0.546 (3)	0.619 (3)	0.2007 (13)	0.075 (9)*
H7A	0.314 (2)	0.9827 (18)	0.2867 (10)	0.035 (5)*
H7B	0.271 (2)	0.9178 (17)	0.2186 (8)	0.022 (4)*
H8	0.582 (2)	1.0556 (16)	0.2591 (8)	0.023 (4)*
H10A	0.521 (3)	0.8057 (18)	0.2971 (9)	0.033 (5)*
H10B	0.702 (2)	0.8791 (18)	0.3163 (9)	0.033 (5)*
H10C	0.706 (2)	0.753 (2)	0.2808 (8)	0.031 (5)*
H11A	0.898 (2)	0.9192 (17)	0.2288 (9)	0.029 (5)*
H11B	0.802 (2)	0.9805 (17)	0.1662 (8)	0.025 (4)*
H12A	0.907 (3)	0.8041 (19)	0.1198 (10)	0.045 (6)*
H12B	0.860 (2)	0.7246 (19)	0.1809 (9)	0.034 (5)*
H15A	0.305 (3)	0.671 (2)	0.1134 (12)	0.062 (7)*
H15B	0.381 (3)	0.666 (2)	0.0440 (13)	0.066 (7)*
H15C	0.358 (3)	0.544 (2)	0.0811 (10)	0.052 (6)*
H16A	0.833 (4)	0.576 (3)	0.0943 (13)	0.076 (8)*
H16B	0.700 (3)	0.620 (2)	0.0297 (13)	0.066 (7)*
H16C	0.670 (3)	0.497 (3)	0.0640 (12)	0.066 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0186 (8)	0.0517 (13)	0.0273 (9)	0.0074 (8)	−0.0011 (7)	0.0007 (8)
C2	0.0219 (8)	0.0278 (9)	0.0199 (8)	−0.0004 (6)	0.0049 (6)	−0.0009 (6)
C3	0.0221 (8)	0.0260 (9)	0.0187 (8)	0.0037 (6)	0.0067 (6)	0.0028 (6)
C4	0.0147 (7)	0.0242 (9)	0.0256 (8)	0.0034 (6)	0.0023 (6)	0.0028 (6)
C5	0.0230 (9)	0.0251 (9)	0.0416 (11)	0.0028 (7)	0.0011 (7)	0.0046 (8)
C6	0.0221 (8)	0.0277 (9)	0.0217 (8)	0.0038 (7)	0.0029 (6)	−0.0025 (7)
C7	0.0233 (8)	0.0321 (10)	0.0189 (8)	0.0017 (7)	0.0054 (6)	0.0012 (7)
C8	0.0238 (8)	0.0226 (9)	0.0176 (7)	−0.0012 (6)	−0.0019 (6)	0.0000 (6)
C9	0.0195 (7)	0.0219 (9)	0.0189 (8)	−0.0023 (6)	−0.0015 (5)	0.0002 (6)
C10	0.0254 (9)	0.0245 (9)	0.0236 (8)	−0.0016 (7)	−0.0010 (6)	0.0030 (7)
C11	0.0195 (8)	0.0266 (9)	0.0297 (9)	−0.0003 (7)	0.0020 (6)	0.0069 (7)
C12	0.0253 (8)	0.0316 (10)	0.0286 (9)	0.0075 (7)	0.0067 (7)	0.0067 (7)
C13	0.0314 (9)	0.0282 (9)	0.0190 (8)	0.0092 (7)	0.0048 (6)	0.0029 (6)
C14	0.0485 (10)	0.0285 (10)	0.0202 (8)	0.0084 (8)	−0.0026 (7)	−0.0008 (7)
C15	0.0622 (14)	0.0306 (11)	0.0420 (12)	−0.0005 (10)	−0.0209 (10)	−0.0035 (9)
C16	0.0878 (18)	0.0364 (13)	0.0347 (12)	0.0210 (12)	0.0121 (11)	−0.0054 (9)
O1	0.0170 (5)	0.0413 (7)	0.0228 (6)	0.0040 (5)	0.0032 (4)	0.0042 (5)
O2	0.0281 (6)	0.0553 (9)	0.0235 (6)	0.0124 (6)	0.0064 (4)	0.0117 (6)
O3	0.0296 (6)	0.0431 (8)	0.0211 (6)	0.0167 (6)	0.0095 (4)	0.0068 (5)
O4	0.0163 (5)	0.0279 (6)	0.0285 (6)	0.0033 (4)	0.0031 (4)	0.0094 (5)
O5	0.0216 (5)	0.0229 (6)	0.0194 (6)	−0.0002 (4)	0.0024 (4)	−0.0038 (4)
O6	0.0369 (7)	0.0386 (7)	0.0251 (6)	0.0139 (6)	0.0090 (5)	0.0127 (5)
O7	0.0471 (8)	0.0264 (7)	0.0277 (7)	0.0048 (6)	−0.0034 (5)	0.0047 (5)

Geometric parameters (Å, º)

C1—O1	1.4512 (19)	C8—C9	1.519 (2)
C2—O2	1.2047 (19)	C9—O5	1.4570 (17)
C2—O1	1.3301 (18)	C9—C10	1.522 (2)
C2—C3	1.516 (2)	C9—C11	1.534 (2)
C3—O3	1.3990 (18)	C11—C12	1.524 (2)
C3—C4	1.557 (2)	C12—C13	1.525 (2)
C4—O4	1.4433 (17)	C13—O6	1.4170 (19)
C4—C5	1.516 (2)	C13—O5	1.4258 (18)
C4—C6	1.532 (2)	C13—C14	1.539 (2)
C6—C7	1.522 (2)	C14—O7	1.435 (2)
C7—C8	1.527 (2)	C14—C16	1.516 (3)
C8—O4	1.4344 (18)	C14—C15	1.525 (3)
O2—C2—O1	123.45 (14)	O5—C9—C11	104.42 (12)
O2—C2—C3	124.79 (13)	C8—C9—C11	113.70 (13)
O1—C2—C3	111.76 (12)	C10—C9—C11	111.73 (12)
O3—C3—C2	105.33 (12)	C12—C11—C9	102.93 (13)
O3—C3—C4	110.83 (12)	C11—C12—C13	102.46 (13)
C2—C3—C4	112.50 (13)	O6—C13—O5	106.74 (12)
O4—C4—C5	107.97 (12)	O6—C13—C12	111.89 (14)
O4—C4—C6	104.40 (11)	O5—C13—C12	105.05 (12)
C5—C4—C6	114.12 (13)	O6—C13—C14	109.47 (13)
O4—C4—C3	106.19 (12)	O5—C13—C14	106.08 (13)
C5—C4—C3	110.81 (13)	C12—C13—C14	116.88 (13)
C6—C4—C3	112.72 (12)	O7—C14—C16	106.07 (15)
C7—C6—C4	103.29 (12)	O7—C14—C15	108.88 (16)
C6—C7—C8	102.38 (13)	C16—C14—C15	111.79 (18)
O4—C8—C9	110.77 (12)	O7—C14—C13	108.13 (13)
O4—C8—C7	105.39 (11)	C16—C14—C13	110.97 (17)
C9—C8—C7	115.81 (13)	C15—C14—C13	110.80 (15)
O5—C9—C8	108.48 (11)	C2—O1—C1	116.01 (12)
O5—C9—C10	108.56 (12)	C8—O4—C4	111.73 (10)
C8—C9—C10	109.67 (13)	C13—O5—C9	111.61 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H03···O6	0.88 (2)	1.86 (3)	2.7250 (16)	166 (2)
O6—H06···O2^i	0.87 (3)	2.08 (3)	2.9381 (16)	171 (2)
O6—H06···O3^i	0.87 (3)	2.30 (3)	2.7973 (16)	116 (2)
O7—H07···O5	0.88 (3)	2.24 (3)	2.7048 (17)	113 (2)

Symmetry code: (i) −x+1, −y+2, −z.