1,5-Asymmetric induction during nucleophilic additions to arene­tricarbonyl­chromium complexes: tri­carbonyl­([eta]⁶-1-methyl-4-{spiro­[(1R,2S)-1,7,7-trimethyl­bicyclo­[2.2.1]heptane-3,2'-1,3-dioxolan]-2-yl­oxy}benzene)­chromium

The tricarbonyl­chromium unit bound to the arene ring of the chiral title complex, [Cr(C₁₉H₂₆O₃)(CO)₃], is rotated by ca 25° in agreement with the proposed mechanism for 1,5-asymmetric induction of nucleophilic attack.

S1. Comment

Arenes (Kündig & Pape, 2004, and references therein) can be converted to cyclohexenes and cyclohexenones by the one-pot sequence of nucleophilic addition to the corresponding arenetricarbonylchromium complex, followed by treatment of the resulting dienylchromium complex with a suitable electrophile and then decomplexation, leading to methodology that finds applications in the synthesis of natural products (Schmalz et al., 2004). When alkoxyarenetricarbonylchromium complexes are used in this sequence, carbon nucleophiles add predominantly to the meta position, ultimately yielding 5-substituted cyclohexenones. [For examples of application of cyclohexenone synthesis, see Pearson et al. (2004).] This reaction can be adapted to give an asymmetric synthesis of 5-substituted cyclohexenones by using chiral alkoxyarenetricarbonylchromiums, as reported earlier from our laboratories (Pearson et al., 1996; Pearson & Gontcharov, 1998; Gontcharov, 1997) and by Semmelhack & Schmalz (1996). Nucleophilic addition to chiral complexes of type (I) presents an interesting example of 1,5 asymmetric induction (Hollowood et al., 2003; Evans et al., 2003; O'Malley & Leighton, 2001; Castelot-Deliencourt et al., 2001), rare in the chemical literature, but the mechanism of asymmetric induction in these reactions is not completely understood.

A plausible mechanism for chirality transmission is by a small rotation of the tricarbonylchromium tripod on the arene ligand. This would lead to a distortion of the complex LUMO, so that its coefficients at the diastereotopic meta positions are unequal, thereby promoting preferential addition at one site (Pearson et al., 1995); in contrast, in simple methoxyarene complexes [(I), R* = CH₃], the tricarbonylchromium Cr—C bonds eclipse the ipso and both meta C atoms of the arene (Semmelhack, 1991). As part of an effort to determine the extent to which the chiral alkoxy group causes this rotation, and therefore whether it might be a causative factor in asymmetric induction, the crystal structures of several alkoxyarenetricarbonylchromium complexes are being studied. We have already reported some of these results for complexes having a trimethylsilyl substituent [R' = Si(CH₃)₃] para to the chiral alkoxy group, all of which structures support our hypothesis (Paramahamsan et al., 2008 or 1980???). In order to show that such rotation of the Cr(CO)₃ group is not specific to the nature of the R' substituents, we have also more recently determined the structure the title complex, (I), a complex bearing a simple alkyl group. The structure of this compound, prepared as described previously (Pearson & Gontcharov, 1998), are reported in the present paper.

As shown in Fig. 1, there is indeed a significant rotation of the Cr(CO)₃ group (ca 25°) [the torsion angles with respect to the centroid (X) of the arene ring are C20—Cr1—X—C13 = 25.5 (2)°, C21—Cr1—X—C15 = 25.9 (2)° and C22—Cr1—X—C17 = 24.1 (2)°], and the direction of rotation is in agreement with the sense of asymmetric induction that we have previously reported during nucleophile additions to this complex (Pearson & Gontcharov, 1998). The rotation of the Cr(CO)₃ unit also removes the mirror symmetry of the arene; for example, the aromatic bonds to atom C16 differ by 0.018 Å, in agreement with the distortion of the LUMO referred to above. Other geometrical parameters are unremarkable.

Related literature

For related literature, see: Gontcharov (1997).

S2. Experimental

Complex (II) was prepared as described previously (Pearson & Gontcharov, 1998), and crystals were obtained by recrystallization from 1:1 hexane/dichloromethane.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2000); software used to prepare material for publication: SHELXTL (Sheldrick, 2000).

Figures

Fig. 1. A view of complex (II), projected on to the plane of the arene ring. Displacement ellipsoids are shown at the 50% probability level.

{η⁶-1-methyl-4-{spiro[(1R,2S)-1,7,7- trimethylbicyclo[2.2.1]heptane-3,2'-1,3-dioxolan]-2- yloxy}benzene}tricarbonylchromium

Crystal data

[Cr(C19H26O3)(CO)3]	F(000) = 460
Mr = 438.43	Dx = 1.410 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1009 reflections
a = 7.9484 (7) Å	θ = 3.4–29.4°
b = 13.6135 (11) Å	µ = 0.59 mm^−1
c = 9.5596 (8) Å	T = 120 K
β = 93.026 (3)°	Plate, orange
V = 1032.96 (15) Å^3	0.25 × 0.15 × 0.05 mm
Z = 2

Data collection

Bruker 6000 CCD area-detector diffractometer	4556 independent reflections
Radiation source: fine-focus sealed tube	4224 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
ω scans	θmax = 29.4°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	h = −8→10
Tmin = 0.908, Tmax = 1.000	k = −18→18
8946 measured reflections	l = −12→12

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)] = 0.040	H-atom parameters constrained
wR(F^2) = 0.090	w = 1/[σ^2(Fo^2) + (0.0446P)^2 + 0.2306P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
4556 reflections	Δρmax = 0.63 e Å^−3
263 parameters	Δρmin = −0.42 e Å^−3
1 restraint	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.041 (18)

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
Cr1	0.13080 (5)	0.88233 (3)	0.81395 (4)	0.01414 (10)
O1	0.3028 (2)	1.00836 (13)	1.31732 (19)	0.0200 (4)
O2	0.5090 (2)	1.07359 (13)	1.19128 (18)	0.0192 (4)
O3	0.4793 (2)	0.92637 (14)	1.01162 (17)	0.0170 (4)
O4	0.1579 (4)	0.71595 (18)	1.0176 (3)	0.0516 (7)
O5	−0.2383 (3)	0.84936 (15)	0.7649 (2)	0.0295 (5)
O6	0.1788 (3)	0.73504 (18)	0.5860 (2)	0.0376 (5)
C1	0.5952 (4)	0.9499 (2)	1.3697 (3)	0.0214 (6)
H1A	0.6465	1.0023	1.4317	0.026*
C2	0.4624 (3)	0.98684 (19)	1.2590 (3)	0.0161 (5)
C3	0.4484 (3)	0.89894 (18)	1.1531 (2)	0.0160 (5)
H3A	0.3346	0.8678	1.1562	0.019*
C4	0.5852 (4)	0.82611 (19)	1.2094 (3)	0.0201 (5)
C5	0.5077 (4)	0.7804 (2)	1.3390 (3)	0.0247 (6)
H5A	0.5748	0.7234	1.3739	0.030*
H5B	0.3905	0.7588	1.3165	0.030*
C6	0.5128 (4)	0.8642 (2)	1.4481 (3)	0.0277 (7)
H6A	0.5816	0.8456	1.5333	0.033*
H6B	0.3979	0.8817	1.4747	0.033*
C7	0.7218 (3)	0.8951 (2)	1.2784 (3)	0.0223 (6)
C8	0.2749 (4)	1.1128 (2)	1.3091 (3)	0.0242 (6)
H8A	0.2409	1.1395	1.3997	0.029*
H8B	0.1874	1.1292	1.2352	0.029*
C9	0.4457 (4)	1.1517 (2)	1.2727 (3)	0.0255 (6)
H9A	0.4349	1.2132	1.2176	0.031*
H9B	0.5189	1.1637	1.3580	0.031*
C10	0.6381 (4)	0.7516 (2)	1.1026 (3)	0.0272 (6)
H10A	0.5396	0.7136	1.0683	0.041*
H10B	0.7223	0.7071	1.1465	0.041*
H10C	0.6866	0.7857	1.0240	0.041*
C11	0.8146 (4)	0.9586 (2)	1.1736 (3)	0.0258 (6)
H11A	0.8985	0.9997	1.2246	0.039*
H11B	0.7333	1.0007	1.1214	0.039*
H11C	0.8712	0.9160	1.1082	0.039*
C12	0.8590 (4)	0.8405 (2)	1.3674 (3)	0.0343 (7)
H12A	0.9409	0.8880	1.4073	0.052*
H12B	0.9165	0.7937	1.3084	0.052*
H12C	0.8071	0.8050	1.4433	0.052*
C13	0.3491 (3)	0.96221 (17)	0.9300 (2)	0.0147 (5)
C14	0.1936 (3)	0.99353 (19)	0.9802 (3)	0.0144 (5)
H14A	0.1671	0.9795	1.0793	0.017*
C15	0.0668 (3)	1.03020 (19)	0.8860 (3)	0.0178 (5)
H15A	−0.0481	1.0423	0.9203	0.021*
C16	0.0906 (3)	1.03614 (19)	0.7403 (3)	0.0196 (5)
C17	0.2434 (3)	1.00178 (19)	0.6923 (3)	0.0187 (5)
H17A	0.2534	0.9925	0.5893	0.022*
C18	0.3722 (3)	0.96410 (18)	0.7851 (3)	0.0167 (5)
H18A	0.4704	0.9291	0.7469	0.020*
C19	−0.0477 (4)	1.0766 (2)	0.6423 (3)	0.0263 (6)
H19A	−0.0494	1.1484	0.6493	0.039*
H19B	−0.1565	1.0502	0.6680	0.039*
H19C	−0.0269	1.0575	0.5459	0.039*
C20	0.1477 (4)	0.7792 (2)	0.9392 (3)	0.0265 (7)
C21	−0.0951 (3)	0.85939 (17)	0.7862 (3)	0.0194 (6)
C22	0.1634 (3)	0.7924 (2)	0.6736 (3)	0.0221 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cr1	0.01533 (17)	0.01069 (16)	0.01619 (17)	−0.00071 (18)	−0.00125 (12)	−0.00059 (18)
O1	0.0176 (9)	0.0190 (9)	0.0236 (9)	0.0035 (7)	0.0046 (7)	−0.0018 (8)
O2	0.0218 (10)	0.0146 (8)	0.0216 (9)	0.0016 (7)	0.0038 (7)	0.0007 (7)
O3	0.0145 (8)	0.0239 (9)	0.0124 (8)	0.0021 (7)	−0.0009 (7)	0.0008 (7)
O4	0.0699 (19)	0.0302 (13)	0.0521 (15)	−0.0192 (13)	−0.0225 (13)	0.0196 (12)
O5	0.0203 (10)	0.0308 (11)	0.0372 (11)	−0.0052 (8)	−0.0007 (8)	0.0010 (9)
O6	0.0328 (12)	0.0371 (12)	0.0423 (13)	0.0038 (10)	−0.0027 (10)	−0.0219 (11)
C1	0.0256 (14)	0.0246 (14)	0.0136 (12)	0.0050 (11)	−0.0028 (10)	−0.0022 (10)
C2	0.0183 (12)	0.0155 (11)	0.0145 (11)	0.0004 (10)	0.0017 (9)	−0.0018 (10)
C3	0.0178 (11)	0.0172 (15)	0.0130 (10)	0.0003 (10)	0.0018 (8)	−0.0004 (9)
C4	0.0267 (14)	0.0167 (13)	0.0170 (12)	0.0046 (11)	0.0009 (10)	0.0024 (10)
C5	0.0323 (16)	0.0227 (14)	0.0193 (13)	0.0082 (12)	0.0029 (12)	0.0042 (12)
C6	0.0371 (15)	0.0276 (18)	0.0186 (12)	0.0113 (12)	0.0024 (11)	0.0038 (11)
C7	0.0222 (12)	0.0238 (16)	0.0204 (11)	0.0055 (12)	−0.0031 (9)	−0.0041 (12)
C8	0.0283 (15)	0.0182 (13)	0.0262 (14)	0.0049 (11)	0.0030 (12)	−0.0034 (11)
C9	0.0275 (15)	0.0164 (13)	0.0325 (15)	0.0029 (11)	−0.0002 (12)	−0.0037 (12)
C10	0.0342 (16)	0.0232 (14)	0.0240 (13)	0.0102 (12)	0.0007 (12)	0.0012 (11)
C11	0.0144 (13)	0.0301 (15)	0.0326 (15)	0.0009 (11)	−0.0007 (11)	−0.0031 (12)
C12	0.0299 (17)	0.0372 (16)	0.0344 (16)	0.0131 (14)	−0.0125 (13)	−0.0005 (14)
C13	0.0177 (12)	0.0113 (11)	0.0148 (11)	−0.0006 (9)	−0.0011 (9)	−0.0010 (9)
C14	0.0158 (13)	0.0137 (12)	0.0136 (12)	−0.0018 (10)	−0.0007 (9)	−0.0006 (10)
C15	0.0139 (12)	0.0128 (11)	0.0264 (13)	−0.0002 (9)	−0.0013 (10)	−0.0037 (10)
C16	0.0219 (13)	0.0113 (11)	0.0250 (13)	−0.0002 (10)	−0.0056 (10)	0.0016 (10)
C17	0.0214 (13)	0.0174 (12)	0.0176 (12)	−0.0033 (11)	0.0023 (10)	0.0006 (10)
C18	0.0173 (13)	0.0154 (12)	0.0177 (12)	0.0001 (10)	0.0024 (10)	0.0005 (10)
C19	0.0283 (15)	0.0199 (13)	0.0295 (14)	0.0052 (12)	−0.0093 (12)	0.0037 (12)
C20	0.0330 (17)	0.0211 (15)	0.0245 (15)	−0.0073 (13)	−0.0072 (13)	0.0042 (12)
C21	0.0205 (13)	0.0155 (14)	0.0222 (12)	0.0001 (9)	0.0016 (10)	−0.0002 (9)
C22	0.0176 (13)	0.0188 (13)	0.0296 (14)	−0.0005 (11)	−0.0008 (11)	−0.0068 (12)

Geometric parameters (Å, º)

Cr1—C21	1.828 (3)	C6—H6B	0.9900
Cr1—C20	1.845 (3)	C7—C12	1.539 (4)
Cr1—C22	1.845 (3)	C7—C11	1.541 (4)
Cr1—C15	2.196 (3)	C8—C9	1.515 (4)
Cr1—C17	2.216 (3)	C8—H8A	0.9900
Cr1—C16	2.227 (3)	C8—H8B	0.9900
Cr1—C14	2.232 (3)	C9—H9A	0.9900
Cr1—C18	2.248 (3)	C9—H9B	0.9900
Cr1—C13	2.285 (3)	C10—H10A	0.9800
O1—C8	1.441 (3)	C10—H10B	0.9800
O1—C2	1.443 (3)	C10—H10C	0.9800
O2—C2	1.406 (3)	C11—H11A	0.9800
O2—C9	1.425 (3)	C11—H11B	0.9800
O3—C13	1.354 (3)	C11—H11C	0.9800
O3—C3	1.436 (3)	C12—H12A	0.9800
O4—C20	1.142 (4)	C12—H12B	0.9800
O5—C21	1.154 (3)	C12—H12C	0.9800
O6—C22	1.155 (3)	C13—C18	1.407 (3)
C1—C2	1.539 (4)	C13—C14	1.415 (4)
C1—C6	1.551 (4)	C14—C15	1.407 (4)
C1—C7	1.557 (4)	C14—H14A	1.0000
C1—H1A	1.0000	C15—C16	1.418 (4)
C2—C3	1.568 (3)	C15—H15A	1.0000
C3—C4	1.547 (4)	C16—C17	1.402 (4)
C3—H3A	1.0000	C16—C19	1.510 (4)
C4—C10	1.514 (4)	C17—C18	1.415 (4)
C4—C5	1.543 (4)	C17—H17A	1.0000
C4—C7	1.556 (4)	C18—H18A	1.0000
C5—C6	1.544 (4)	C19—H19A	0.9800
C5—H5A	0.9900	C19—H19B	0.9800
C5—H5B	0.9900	C19—H19C	0.9800
C6—H6A	0.9900
C21—Cr1—C20	90.08 (13)	C12—C7—C1	112.4 (2)
C21—Cr1—C22	87.45 (12)	C11—C7—C1	116.1 (2)
C20—Cr1—C22	87.64 (14)	C4—C7—C1	94.0 (2)
C21—Cr1—C15	87.72 (10)	O1—C8—C9	102.7 (2)
C20—Cr1—C15	120.25 (12)	O1—C8—H8A	111.2
C22—Cr1—C15	151.68 (12)	C9—C8—H8A	111.2
C21—Cr1—C17	118.05 (11)	O1—C8—H8B	111.2
C20—Cr1—C17	151.82 (12)	C9—C8—H8B	111.2
C22—Cr1—C17	91.68 (11)	H8A—C8—H8B	109.1
C15—Cr1—C17	66.33 (10)	O2—C9—C8	102.2 (2)
C21—Cr1—C16	89.50 (10)	O2—C9—H9A	111.3
C20—Cr1—C16	157.64 (12)	C8—C9—H9A	111.3
C22—Cr1—C16	114.67 (11)	O2—C9—H9B	111.3
C15—Cr1—C16	37.40 (10)	C8—C9—H9B	111.3
C17—Cr1—C16	36.78 (10)	H9A—C9—H9B	109.2
C21—Cr1—C14	113.59 (10)	C4—C10—H10A	109.5
C20—Cr1—C14	92.76 (11)	C4—C10—H10B	109.5
C22—Cr1—C14	158.95 (11)	H10A—C10—H10B	109.5
C15—Cr1—C14	37.03 (9)	C4—C10—H10C	109.5
C17—Cr1—C14	78.15 (9)	H10A—C10—H10C	109.5
C16—Cr1—C14	67.07 (9)	H10B—C10—H10C	109.5
C21—Cr1—C18	154.84 (10)	C7—C11—H11A	109.5
C20—Cr1—C18	115.03 (12)	C7—C11—H11B	109.5
C22—Cr1—C18	94.94 (11)	H11A—C11—H11B	109.5
C15—Cr1—C18	78.34 (9)	C7—C11—H11C	109.5
C17—Cr1—C18	36.96 (10)	H11A—C11—H11C	109.5
C16—Cr1—C18	66.73 (10)	H11B—C11—H11C	109.5
C14—Cr1—C18	65.87 (9)	C7—C12—H12A	109.5
C21—Cr1—C13	150.08 (10)	C7—C12—H12B	109.5
C20—Cr1—C13	91.13 (11)	H12A—C12—H12B	109.5
C22—Cr1—C13	122.47 (11)	C7—C12—H12C	109.5
C15—Cr1—C13	66.04 (9)	H12A—C12—H12C	109.5
C17—Cr1—C13	65.67 (9)	H12B—C12—H12C	109.5
C16—Cr1—C13	78.39 (9)	O3—C13—C18	116.0 (2)
C14—Cr1—C13	36.49 (9)	O3—C13—C14	124.6 (2)
C18—Cr1—C13	36.16 (9)	C18—C13—C14	119.3 (2)
C8—O1—C2	108.4 (2)	O3—C13—Cr1	130.25 (17)
C2—O2—C9	105.45 (19)	C18—C13—Cr1	70.50 (14)
C13—O3—C3	118.21 (18)	C14—C13—Cr1	69.72 (14)
C2—C1—C6	106.6 (2)	C15—C14—C13	119.9 (2)
C2—C1—C7	102.2 (2)	C15—C14—Cr1	70.10 (14)
C6—C1—C7	102.2 (2)	C13—C14—Cr1	73.79 (14)
C2—C1—H1A	114.8	C15—C14—H14A	119.7
C6—C1—H1A	114.8	C13—C14—H14A	119.7
C7—C1—H1A	114.8	Cr1—C14—H14A	119.7
O2—C2—O1	105.4 (2)	C14—C15—C16	121.4 (2)
O2—C2—C1	113.8 (2)	C14—C15—Cr1	72.87 (15)
O1—C2—C1	112.7 (2)	C16—C15—Cr1	72.48 (15)
O2—C2—C3	110.83 (19)	C14—C15—H15A	119.0
O1—C2—C3	111.8 (2)	C16—C15—H15A	119.0
C1—C2—C3	102.6 (2)	Cr1—C15—H15A	119.0
O3—C3—C4	109.99 (19)	C17—C16—C15	117.7 (2)
O3—C3—C2	113.6 (2)	C17—C16—C19	122.3 (2)
C4—C3—C2	103.87 (19)	C15—C16—C19	120.0 (2)
O3—C3—H3A	109.8	C17—C16—Cr1	71.17 (15)
C4—C3—H3A	109.8	C15—C16—Cr1	70.13 (14)
C2—C3—H3A	109.8	C19—C16—Cr1	128.82 (19)
C10—C4—C5	114.1 (2)	C16—C17—C18	121.8 (2)
C10—C4—C3	114.2 (2)	C16—C17—Cr1	72.04 (15)
C5—C4—C3	103.6 (2)	C18—C17—Cr1	72.76 (15)
C10—C4—C7	118.5 (2)	C16—C17—H17A	118.7
C5—C4—C7	101.6 (2)	C18—C17—H17A	118.7
C3—C4—C7	102.9 (2)	Cr1—C17—H17A	118.7
C4—C5—C6	104.3 (2)	C13—C18—C17	119.7 (2)
C4—C5—H5A	110.9	C13—C18—Cr1	73.35 (14)
C6—C5—H5A	110.9	C17—C18—Cr1	70.28 (15)
C4—C5—H5B	110.9	C13—C18—H18A	119.7
C6—C5—H5B	110.9	C17—C18—H18A	119.7
H5A—C5—H5B	108.9	Cr1—C18—H18A	119.7
C5—C6—C1	103.1 (2)	C16—C19—H19A	109.5
C5—C6—H6A	111.2	C16—C19—H19B	109.5
C1—C6—H6A	111.2	H19A—C19—H19B	109.5
C5—C6—H6B	111.2	C16—C19—H19C	109.5
C1—C6—H6B	111.2	H19A—C19—H19C	109.5
H6A—C6—H6B	109.1	H19B—C19—H19C	109.5
C12—C7—C11	106.3 (2)	O4—C20—Cr1	179.4 (3)
C12—C7—C4	113.7 (3)	O5—C21—Cr1	176.5 (2)
C11—C7—C4	114.2 (2)	O6—C22—Cr1	177.9 (2)