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organic papers

Acta Cryst.(2005). E61, o1123–o1124 doi:10.1107/S1600536805008743 George R. Clarket al. C

17H16O3

o1123

Acta Crystallographica Section E Structure Reports Online

ISSN 1600-5368

5-Methoxyspiro[1-benzofuran-2(3

H

),2

000

-chroman]

George R. Clark,* Kit Yee Tsang and Margaret A. Brimble

Chemistry Department, University of Auckland, Private Bag 92019, Auckland, New Zealand

Correspondence e-mail: g.clark@auckland.ac.nz

Key indicators

Single-crystal X-ray study T= 200 K

Mean(C–C) = 0.003 A˚ Rfactor = 0.030 wRfactor = 0.080 Data-to-parameter ratio = 7.6

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

#2005 International Union of Crystallography Printed in Great Britain – all rights reserved

The crystal structure of the title compound, C17H16O3, has

been determined to establish the relative stereochemistry at the spiro ring junction. Both O atoms adjacent to the junction adopt axial positions because of anomeric effects.

Comment

The rubromycins (Brockmann et al., 1969; Brockmann & Zeeck, 1970) are microbial secondary metabolites (Puder et al., 2000) that exhibit antibacterial and cytostatic activity. -Rubromycin contains naphthoquinone and isocoumarin rings linked to a 5,6 spiroacetal system.-Rubromycin is one of the most potent human telomerase inhibitors, with 50% inhibitory concentrations (IC50) of about 3mM(Uenoet al., 2000). It also

exhibits inhibitory activity towards retroviral reverse tran-scriptase and human immunodeficiency virus type 1 reverse transcriptase. In order to examine the ability of the 5,6-aryl spiroacetal unit to inhibit human telomerase, the analogue of rubromycin, 5-methoxyspiro[1-benzofuran-2(3H),2-chroman], (2), was synthesized. The conformation of this 5,6-aryl spiro-acetal was determined and is reported here. The title molecule is shown in Fig. 1 and selected bond lengths and angles are given in Table 1. The geometry at the spiro ring junction reflects the constraints of fusing five-membered and

six-membered rings together, i.e. the angles O1—C1—C2 and

O2—C1—C10 are 111.6 (2) and 117.1 (2)respectively.

Experimental

A solution of ketone (1) (0.27 mmol) in dry dichloromethane (1.5 ml) containing 4 A˚ molecular sieves (75 mg) was treated with bromotri-methylsilane (2.47 mmol) at 243 K. After 2 h, the reaction mixture was warmed to 273 K for 4 h then warmed to room temperature for another 2 h. The reaction mixture was poured into a solution of saturated sodium bicarbonate (2 ml) and extracted with diethyl ether (42 ml). The combined organic extracts were washed with brine (5 ml), dried over magnesium sulfate and concentrated under reduced pressure to give a white solid. Purification by flash column

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chromatography using hexane- ethyl acetate (80:20) afforded the title compound (2), as a white solid that was recrystallized from ethyl acetate to give colourless needles (37 mg, 51%, m.p. 363–365 K. MS (EI, %) 268 (M+, 32), 161 (100), 131 (6), 107 (12), 77 (6), 65 (3),

45 (3). HR–MS (EI) Found M+, 268.10970, C17H16O3 requires

268.10994.max(film)/cm

13054, 2986, 2959, 2930, 2305, 1584, 1488,

1457, 1466, 1433, 1422, 1265, 1222, 1209, 1177, 736, 705.H(300 MHz,

CDCl3) 2.17 (1H,ddd, J30ax,40eq6.0,J30ax,40ax13.3 Hz andJgem13.3 Hz, H-30

ax), 2.31 (1H,ddd, J30eq,40eq2.8,J30eq,40ax6.0 andJgem13.3 Hz, H-30

eq), 2.81 (1H,ddd, J40eq,30eq2.8,J40eq,30ax6.0 andJgem16.4 Hz, H-40eq), 3.17–3.27 (1H,m, H-40

ax), 3.26 (1H,Jgem16.6 Hz, HA-3), 3.41 (1H,

Jgem16.6 Hz, HB-3), 3.76 (3H,s, OMe), 6.69 (2H,m, H-4 and H-6),

6.77–6.82 (2H,m, H-7 and H-80), 6.90 (1H,dt, J1.1 and 7.9 Hz, H-60),

7.07–7.13 (2H,m, H-50 and H-70).

C(75 MHz, CDCl3) 21.9 (CH2,

C-40), 30.4 (CH

2, C-30), 42.3 (CH2, C-3), 56.0 (CH3, OMe), 109.2 (quat.,

C-2), 109.8 (CH, C-6), 111.2 (CH, C-80), 113.0 (CH, C-4), 117.1 (CH,

C-7), 121.1 (CH, C-60), 121.4 (quat., C-40a), 126.3 (quat., C-3a), 127.4

(CH, C-70), 129.1 (CH, C-50), 152.0 (quat., C-7a), 152.3 (quat., C-80a),

154.6 (quat., C-5).

Crystal data

C17H16O3

Mr= 268.30 Monoclinic,Pc a= 10.3982 (7) A˚

b= 5.7749 (4) A˚

c= 11.2480 (8) A˚ = 96.132 (1)

V= 671.56 (8) A˚3

Z= 2

Dx= 1.327 Mg m3

MoKradiation Cell parameters from 3003

reflections = 3.5–26.4

= 0.09 mm1

T= 200 (2) K Block, colourless 0.340.300.24 mm

Data collection

Bruker SMART CCD diffractometer !scans

Absorption correction: multi-scan (SADABS; Sheldrick, 1997)

Tmin= 0.970,Tmax= 0.979

3951 measured reflections

1367 independent reflections 1250 reflections withI> 2(I)

Rint= 0.017

max= 26.4

h=12!12

k=7!7

l=14!14

Refinement

Refinement onF2 R[F2> 2(F2)] = 0.030

wR(F2) = 0.080

S= 1.02 1367 reflections 181 parameters

H-atom parameters constrained

w= 1/[2

(Fo2) + (0.0556P)2 + 0.0273P]

whereP= (Fo2+ 2Fc2)/3 (/)max= 0.001

max= 0.11 e A˚ 3

[image:2.610.44.296.71.157.2]

min=0.16 e A˚ 3

Table 1

Selected geometric parameters (A˚ ,).

O1—C5 1.384 (3)

O1—C1 1.421 (2)

O2—C12 1.381 (2)

O2—C1 1.454 (2)

C1—C2 1.507 (3)

C1—C10 1.535 (3)

C2—C3 1.518 (3)

C3—C4 1.506 (3)

C4—C5 1.395 (3)

C10—C11 1.506 (3)

C11—C12 1.394 (3)

C5—O1—C1 117.56 (16)

C12—O2—C1 107.62 (15)

O1—C1—O2 107.49 (15)

O1—C1—C2 111.63 (18)

O2—C1—C2 107.36 (17)

O1—C1—C10 106.41 (17)

O2—C1—C10 106.37 (16)

C2—C1—C10 117.11 (18)

C1—C2—C3 110.20 (18)

C4—C3—C2 110.06 (18)

C5—C4—C3 119.54 (18)

O1—C5—C4 123.44 (18)

C11—C10—C1 102.72 (17)

C12—C11—C10 107.80 (19)

O2—C12—C11 112.73 (17)

H atoms were placed in calculated positions [C—H 0.93–0.97 A˚ ] and refined using a riding model, with Uiso(H) = 1.2 or 1.5 times

Ueq(C). In the absence of significant anomalous dispersion effects, the

Friedel pairs were merged before refinement.

Data collection:SMART(Siemens, 1995); cell refinement:SAINT (Siemens, 1995); data reduction:SAINT; program(s) used to solve structure:SHELXS97(Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication:SHELXTL(Siemens, 1995).

References

Brockmann, H., Lenk, W., Schwantje, G. & Zeeck, A. (1969).Chem. Ber.102, 126–151.

Brockmann, H. & Zeeck, A. (1970).Chem. Ber.103, 1709–1726.

Burnett, M. N. & Johnson, C. K. (1996).ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.

Puder, C., Loya, S., Hizi, A. & Zeeck, A. (2000).Eur. J. Org. Chem.729– 735.

Sheldrick, G. M. (1997).SADABS.University of Go¨ttingen, Germany. Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of

Go¨ttingen, Germany.

Siemens (1995). SMART, SAINT and SHELXTL. Siemens Analytical Instruments Inc., Madison, Wisconsin, USA.

Ueno, T., Takahashi, H., Mizunuma, M., Yokoyama, A., Goto, Y., Mizushina, Y., Sakaguchi, K. & Jayashi, H. (2000).Biochemistry,39, 5995–6002.

Figure 1

[image:2.610.313.567.193.323.2]
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supporting information

sup-1

Acta Cryst. (2005). E61, o1123–o1124

supporting information

Acta Cryst. (2005). E61, o1123–o1124 [https://doi.org/10.1107/S1600536805008743]

5-Methoxyspiro[1-benzofuran-2(3

H

),2

-chroman]

George R. Clark, Kit Yee Tsang and Margaret A. Brimble

(2)

Crystal data

C17H16O3

Mr = 268.30 Monoclinic, Pc

Hall symbol: P -2yc

a = 10.3982 (7) Å

b = 5.7749 (4) Å

c = 11.2480 (8) Å

β = 96.132 (1)°

V = 671.56 (8) Å3

Z = 2

F(000) = 284

Dx = 1.327 Mg m−3

Mo radiation, λ = 0.71073 Å Cell parameters from 3003 reflections

θ = 3.5–26.4°

µ = 0.09 mm−1

T = 200 K Plate, colourless 0.34 × 0.30 × 0.24 mm

Data collection

Bruker SMART CCD diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

ω scans

Absorption correction: multi-scan (SADABS; Sheldrick, 1997)

Tmin = 0.970, Tmax = 0.979

3951 measured reflections 1367 independent reflections 1250 reflections with I > 2σ(I)

Rint = 0.017

θmax = 26.4°, θmin = 3.5°

h = −12→12

k = 0→7

l = −14→14

Refinement

Refinement on F2

Least-squares matrix: full

R[F2 > 2σ(F2)] = 0.030

wR(F2) = 0.080

S = 1.02 1367 reflections 181 parameters 2 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

Hydrogen site location: inferred from neighbouring sites

H-atom parameters constrained

w = 1/[σ2(F

o2) + (0.0556P)2 + 0.0273P]

where P = (Fo2 + 2Fc2)/3

(Δ/σ)max = 0.001

Δρmax = 0.11 e Å−3

Δρmin = −0.16 e Å−3

Special details

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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 (Å2)

x y z Uiso*/Ueq

O1 0.03458 (14) 0.4680 (2) 0.55306 (14) 0.0358 (4)

O2 0.24126 (13) 0.4178 (3) 0.64904 (12) 0.0338 (3)

O3 0.53655 (15) 1.0370 (3) 0.42617 (13) 0.0434 (4)

C1 0.1505 (2) 0.3391 (4) 0.55002 (19) 0.0315 (4)

C2 0.1287 (2) 0.0841 (4) 0.5679 (2) 0.0378 (5)

H2A 0.2108 −0.0010 0.5639 0.045*

H2B 0.0648 0.0254 0.5034 0.045*

C3 0.0795 (2) 0.0420 (4) 0.6884 (2) 0.0383 (5)

H3A 0.0514 −0.1211 0.6937 0.046*

H3B 0.1501 0.0701 0.7531 0.046*

C4 −0.03236 (19) 0.2010 (4) 0.70374 (18) 0.0349 (5)

C5 −0.0477 (2) 0.4034 (4) 0.63612 (19) 0.0331 (4)

C6 −0.1510 (2) 0.5537 (4) 0.6466 (2) 0.0430 (6)

H6 −0.1608 0.6897 0.5990 0.052*

C7 −0.2389 (2) 0.5033 (5) 0.7268 (3) 0.0520 (7)

H7 −0.3088 0.6061 0.7350 0.062*

C8 −0.2257 (3) 0.3036 (5) 0.7951 (2) 0.0545 (7)

H8 −0.2862 0.2694 0.8502 0.065*

C9 −0.1235 (2) 0.1535 (5) 0.7827 (2) 0.0457 (6)

H9 −0.1156 0.0156 0.8290 0.055*

C10 0.2076 (2) 0.4115 (4) 0.4352 (2) 0.0370 (5)

H10A 0.2465 0.2777 0.3973 0.044*

H10B 0.1408 0.4823 0.3770 0.044*

C11 0.30908 (19) 0.5859 (3) 0.48007 (18) 0.0302 (4)

C12 0.32165 (18) 0.5793 (3) 0.60465 (17) 0.0282 (4)

C13 0.40557 (19) 0.7204 (4) 0.67337 (18) 0.0320 (4)

H13 0.4131 0.7117 0.7582 0.038*

C14 0.4798 (2) 0.8775 (4) 0.61507 (19) 0.0331 (4)

H14 0.5383 0.9783 0.6605 0.040*

C15 0.4683 (2) 0.8865 (4) 0.49042 (19) 0.0328 (4)

C16 0.3824 (2) 0.7405 (3) 0.42229 (17) 0.0319 (4)

H16 0.3746 0.7473 0.3374 0.038*

C17 0.6196 (3) 1.1979 (5) 0.4932 (3) 0.0522 (7)

H17A 0.6635 1.2943 0.4383 0.078*

H17B 0.6841 1.1132 0.5463 0.078*

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supporting information

sup-3

Acta Cryst. (2005). E61, o1123–o1124 Atomic displacement parameters (Å2)

U11 U22 U33 U12 U13 U23

O1 0.0347 (8) 0.0300 (7) 0.0428 (8) 0.0033 (6) 0.0047 (6) 0.0044 (6)

O2 0.0360 (7) 0.0361 (7) 0.0288 (7) −0.0069 (6) 0.0010 (6) 0.0007 (6)

O3 0.0458 (9) 0.0506 (10) 0.0336 (9) −0.0152 (8) 0.0033 (7) 0.0056 (7)

C1 0.0303 (9) 0.0307 (10) 0.0329 (10) 0.0011 (8) 0.0005 (8) −0.0037 (9)

C2 0.0375 (11) 0.0286 (10) 0.0474 (14) 0.0024 (9) 0.0046 (10) −0.0035 (9)

C3 0.0382 (11) 0.0273 (10) 0.0484 (14) −0.0013 (9) 0.0002 (9) 0.0067 (9)

C4 0.0326 (11) 0.0353 (10) 0.0355 (11) −0.0040 (9) −0.0025 (9) −0.0033 (9)

C5 0.0310 (10) 0.0325 (10) 0.0352 (11) −0.0016 (8) 0.0000 (8) −0.0057 (8)

C6 0.0378 (11) 0.0404 (13) 0.0499 (14) 0.0050 (10) 0.0000 (10) −0.0077 (10)

C7 0.0369 (12) 0.0620 (16) 0.0570 (16) 0.0075 (11) 0.0046 (12) −0.0180 (13)

C8 0.0424 (13) 0.0743 (18) 0.0484 (15) −0.0064 (13) 0.0128 (11) −0.0093 (14)

C9 0.0429 (12) 0.0527 (14) 0.0413 (13) −0.0086 (11) 0.0035 (10) 0.0011 (11)

C10 0.0417 (11) 0.0396 (11) 0.0297 (11) −0.0061 (9) 0.0035 (9) −0.0050 (9)

C11 0.0307 (9) 0.0299 (9) 0.0298 (10) 0.0045 (8) 0.0018 (8) −0.0042 (8)

C12 0.0289 (9) 0.0285 (9) 0.0275 (10) 0.0040 (8) 0.0039 (8) 0.0014 (8)

C13 0.0333 (10) 0.0377 (11) 0.0247 (10) 0.0007 (8) 0.0014 (8) 0.0001 (8)

C14 0.0313 (10) 0.0368 (11) 0.0306 (10) −0.0029 (9) −0.0003 (8) −0.0016 (9)

C15 0.0320 (10) 0.0344 (10) 0.0321 (11) 0.0013 (8) 0.0044 (8) 0.0035 (8)

C16 0.0356 (10) 0.0367 (10) 0.0232 (10) 0.0009 (8) 0.0029 (8) 0.0001 (8)

C17 0.0556 (15) 0.0530 (15) 0.0470 (14) −0.0204 (12) 0.0007 (12) 0.0069 (12)

Geometric parameters (Å, º)

O1—C5 1.384 (3) C7—H7 0.9500

O1—C1 1.421 (2) C8—C9 1.391 (4)

O2—C12 1.381 (2) C8—H8 0.9500

O2—C1 1.454 (2) C9—H9 0.9500

O3—C15 1.375 (2) C10—C11 1.506 (3)

O3—C17 1.428 (3) C10—H10A 0.9900

C1—C2 1.507 (3) C10—H10B 0.9900

C1—C10 1.535 (3) C11—C16 1.381 (3)

C2—C3 1.518 (3) C11—C12 1.394 (3)

C2—H2A 0.9900 C12—C13 1.370 (3)

C2—H2B 0.9900 C13—C14 1.399 (3)

C3—C4 1.506 (3) C13—H13 0.9500

C3—H3A 0.9900 C14—C15 1.395 (3)

C3—H3B 0.9900 C14—H14 0.9500

C4—C9 1.393 (3) C15—C16 1.396 (3)

C4—C5 1.395 (3) C16—H16 0.9500

C5—C6 1.395 (3) C17—H17A 0.9800

C6—C7 1.382 (4) C17—H17B 0.9800

C6—H6 0.9500 C17—H17C 0.9800

C7—C8 1.384 (4)

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C12—O2—C1 107.62 (15) C8—C9—C4 121.4 (2)

C15—O3—C17 116.81 (18) C8—C9—H9 119.3

O1—C1—O2 107.49 (15) C4—C9—H9 119.3

O1—C1—C2 111.63 (18) C11—C10—C1 102.72 (17)

O2—C1—C2 107.36 (17) C11—C10—H10A 111.2

O1—C1—C10 106.41 (17) C1—C10—H10A 111.2

O2—C1—C10 106.37 (16) C11—C10—H10B 111.2

C2—C1—C10 117.11 (18) C1—C10—H10B 111.2

C1—C2—C3 110.20 (18) H10A—C10—H10B 109.1

C1—C2—H2A 109.6 C16—C11—C12 119.57 (18)

C3—C2—H2A 109.6 C16—C11—C10 132.61 (19)

C1—C2—H2B 109.6 C12—C11—C10 107.80 (19)

C3—C2—H2B 109.6 C13—C12—O2 124.82 (18)

H2A—C2—H2B 108.1 C13—C12—C11 122.45 (19)

C4—C3—C2 110.06 (18) O2—C12—C11 112.73 (17)

C4—C3—H3A 109.6 C12—C13—C14 118.10 (19)

C2—C3—H3A 109.6 C12—C13—H13 120.9

C4—C3—H3B 109.6 C14—C13—H13 120.9

C2—C3—H3B 109.6 C15—C14—C13 120.16 (19)

H3A—C3—H3B 108.2 C15—C14—H14 119.9

C9—C4—C5 117.8 (2) C13—C14—H14 119.9

C9—C4—C3 122.6 (2) O3—C15—C16 115.39 (18)

C5—C4—C3 119.54 (18) O3—C15—C14 123.89 (19)

O1—C5—C4 123.44 (18) C16—C15—C14 120.71 (19)

O1—C5—C6 115.25 (19) C11—C16—C15 119.01 (18)

C4—C5—C6 121.3 (2) C11—C16—H16 120.5

C7—C6—C5 119.5 (2) C15—C16—H16 120.5

C7—C6—H6 120.2 O3—C17—H17A 109.5

C5—C6—H6 120.2 O3—C17—H17B 109.5

C6—C7—C8 120.3 (2) H17A—C17—H17B 109.5

C6—C7—H7 119.8 O3—C17—H17C 109.5

C8—C7—H7 119.8 H17A—C17—H17C 109.5

C7—C8—C9 119.7 (2) H17B—C17—H17C 109.5

Figure

Figure 1

References

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