Silver perchlorate induced rearrangement of a tetraarylethene involving an apparent oxygen migration

Article abstract of DOI:10.1016/j.tetlet.2014.02.026

An H-shaped tetraarylethene ligand was prepared and shown to react with silver perchlorate to produce a crystalline silver complex of a rearranged ligand. X-ray crystallography revealed that this involved the formation of a phenanthrene ring system with the apparent migration of an oxygen atom. We believe that this rearrangement proceeds via the intermediacy of a spirodienone.

Full text of DOI:10.1016/j.tetlet.2014.02.026

Tetrahedron Letters 55 (2014) 2019–2021
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Tetrahedron Letters
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Silver perchlorate induced rearrangement of a tetraarylethene
involving an apparent oxygen migration
⇑
Solomon W. Kelemu, Christopher M. Fitchett, Peter J. Steel
Department of Chemistry, University of Canterbury, Christchurch 8140, New Zealand
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 21 February 2014
An H-shaped tetraarylethene ligand was prepared and shown to react with silver perchlorate to produce
a crystalline silver complex of a rearranged ligand. X-ray crystallography revealed that this involved the
formation of a phenanthrene ring system with the apparent migration of an oxygen atom. We believe
that this rearrangement proceeds via the intermediacy of a spirodienone.
Keywords:
Rearrangement
Silver perchlorate
Crystal structure
Dienone-phenol rearrangement
Tetraarylethene
Ó 2014 Elsevier Ltd. All rights reserved.
Metallosupramolecular chemistry1 involves the use of bridging
organic ligands and metal centres for the construction of 0, 1, 2 or
3D assemblies.2 The use of silver(I) for such purposes has been par-
ticularly popular in recent years.3 For some time now we have
championed the use of the silver–alkene interaction as a useful
synthon for access to novel metallosupramolecular assemblies.4
For example, we showed that three isomeric divinylbenzenes re-
acted with silver(I) salts to give both discrete and polymeric
species.5
Recently, we described the use of an H-shaped ligand 1 with
four allyloxy arms as coordinating units for the construction of a
molecular ladder that underwent double interpenetration to form
the first example of an elusive metallosupramolecular topology.6
We now report the synthesis and characterisation of a structurally
related ligand 2 that, upon reaction with silver(I) perchlorate,
undergoes an intriguing molecular rearrangement.
The potential ligand was prepared in a two-step procedure
starting from 4,40-dihydroxybenzophenone. McMurry coupling7
generated a tetraarylethene, which was directly allylated,8 as
shown in Scheme 1, to give the four-armed ligand 2. This was fully
characterised9 by 1H and 13C NMR, infrared spectroscopy, mass
spectrometry, elemental analysis and the structure confirmed by
X-ray crystallography (Scheme 1). It crystallises in the monoclinic
space group P21/n with a full molecule in the asymmetric unit.10
O
O
O
O
O
O
O
O
1
2
Reaction of 2 with silver(I) perchlorate in an acetone solution
and slow evaporation of the solvent over two weeks furnished
crystals of a silver complex11 of the rearranged ligand 4, as demon-
strated by a single crystal X-ray structure determination. The crys-
tal structure of this complex shows that it exists as a complicated
2D assembly, a section of which is shown in Figure 1. It crystallises
in the triclinic space group P-1 and the asymmetric unit contains
one full molecule of 4, one and a half silver atoms, a coordinated
water molecule and one and a half non-coordinated perchlorate
anions.12 All three remaining allyl arms of 4 are coordinated to
silver, with bond lengths comparable to those in related silver–
alkene complexes.4,5,13 The silver atoms are three- and four-
coordinate. The phenyl rings attached to the planar phenanthrene
ring system are approximately orthogonal to that plane and expe-
rience edge-to-face
p–p interactions with a symmetry-related
phenanthrene ring with separation distances of 3.613 and 3.664 Å.
In order to confirm that the crystal used was not a minor
by-product in a mixture, we recorded the powder diffraction
pattern of the bulk sample, which confirmed that the complex
⇑
Corresponding author. Tel.: +64 3 3642432; fax: +64 3 3642110.
E-mail address: peter.steel@canterbury.ac.nz (P.J. Steel).
http://dx.doi.org/10.1016/j.tetlet.2014.02.026
0040-4039/Ó 2014 Elsevier Ltd. All rights reserved.

2020
S. W. Kelemu et al. / Tetrahedron Letters 55 (2014) 2019–2021
Scheme 1. Synthesis of 2, its X-ray crystal structure and rearrangement into 4.
metal-catalysed rearrangement of 1,2-bis(4-alkoxyphenyl) precur-
sors16,17 and undergo dienone-phenol rearrangements into phe-
nanthrenes18,19 with selective migration of the alkenyl group.19
Reactions of 2 with other silver(I) salts did not induce this rear-
rangement and complexes of unrearranged 2 were able to be char-
acterised.20 In addition, a linear 1D coordination complex of 2 with
silver perchlorate was formed in low yields by carrying out the
reaction over a shorter timeframe in acetonitrile.20
In conclusion, the H-shaped ligand 2 was prepared in two steps
and fully characterised, including an X-ray crystal structure. Reac-
tion of 2 with silver perchlorate resulted in the isolation of crystals
of a silver complex of the rearranged ligand 4, involving an appar-
ent oxygen migration. We believe that this reaction proceeds via
the intermediate spirodienone 3.
Figure 1. X-ray structure of a section of the 2D coordination polymer of the silver
complex of rearranged ligand 4.
was the sole product (see Supplementary data). Indeed the 1H NMR
spectrum of the crystals dissolved in acetonitrile showed a single
compound, the spectrum of which was assigned (Fig. 2) with the
aid of 2D experiments. The dissolved crystals were decomplexed
from the silver by passage through a column of silica, thereby
allowing the isolation and characterisation of 4 itself.14
Only one compound has been reported with this carbon skele-
ton and oxygenation pattern, as a minor product in a palladium-
catalysed coupling reaction.15 The rearrangement of 2 into 4
involves the loss of one allyl group, the formation of a CAC bond
between two phenyl rings to generate the phenanthrene ring sys-
tem and the apparent migration of an oxygen atom. We believe
that this rearrangement proceeds through the intermediacy of
dienone 3 (Scheme 1). Such spirodienones are known to form by
Acknowledgments
We thank the University of Canterbury, College of Science, for a
scholarship for S.W.K. and the RSNZ Marsden fund for generous
financial support.
Supplementary data
Supplementary data (X-ray powder diffraction figure and X-ray
CIFs) associated with this article can be found, in the online ver-
sion, at http://dx.doi.org/10.1016/j.tetlet.2014.02.026.
References and notes
1. (a) Constable, E. C. Chem. Ind. 1994, 56; (b) Steel, P. J. Chem. N. Z. 2003, 67, 57.
2. (a) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. Rev. 2000, 100, 853; (b) Lindoy, L.
F.; Atkinson, I. M. Self-Assembly in Supramolecular Systems; Cambridge
University Press: Cambridge, UK, 2000; (c) Steed, J. W.; Atwood, J. L.
Supramolecular Chemistry, 2nd Ed.; J. Wiley & Sons: Chichester, 2009; (d)
Hosseini, M. W. Acc. Chem. Res. 2005, 38, 313; (e) Halcrow, M. A. Dalton Trans.
2009, 2059; (f) Chakrabarty, R.; Mukherjee, P. S.; Stang, P. J. Chem. Rev. 2011,
111, 6810.
3. (a) Munakata, M.; Wu, L. P.; Kuroda-Sowa, T. Adv. Inorg. Chem. 1999, 46, 173;
(b) Khlobystov, A. N.; Blake, A. J.; Champness, N. R.; Lemenovskii, D. A.;
Majouga, A. G.; Zyk, N. V.; Schröder, M. Coord. Chem. Rev. 2001, 222, 155; (c)
Zheng, S.-L.; Tong, M.-L.; Chen, X.-M. Coord. Chem. Rev. 2003, 246, 185; (d) Steel,
P. J. Acc. Chem. Res. 2005, 38, 243; (e) Chen, C.-L.; Kang, B.-S.; Su, C.-Y. Aust. J.
Chem. 2006, 59, 3; (f) Steel, P. J.; Fitchett, C. M. Coord. Chem. Rev. 2008, 252, 990;
(g) Young, A. G.; Hanton, L. R. Coord. Chem. Rev. 2008, 252, 1346.
4. Burgess, J.; Steel, P. J. Coord. Chem. Rev. 2011, 255, 2094.
5. Burgess, J.; Cottam, J. R. A.; Steel, P. J. Aust. J. Chem. 2006, 59, 295.
6. Kelemu, S. W.; Steel, P. J. Eur. J. Inorg. Chem. 2014, 434.
7. (a) McMurry, J. E.; Fleming, M. P. J. Am. Chem. Soc. 1974, 96, 4708; (b) McMurry,
J. E. Chem. Rev. 1989, 89, 1513.
8. Antonsen, O.; Benneche, T.; Undheim, K. Acta Chem. Scand. 1988, B42, 515.
Figure 2. 1H NMR spectrum of the crystals of the silver complex 4 dissolved in
d3-acetonitrile.

S. W. Kelemu et al. / Tetrahedron Letters 55 (2014) 2019–2021
2021
9. Data for 2: mp 46–48 °C. 1H NMR (500 MHz, CDCl3): d 4.46 (8H, br d, J = 3.0 Hz,
H6), 5.26 (4H, dd, J = 10.5, 1.5 Hz, H8), 5.39 (4H, dd, J = 17.0, 1.5 Hz, H80), 5.98–
6.06 (4H, m, H7), 6.65 (8H, d, J = 8.5 Hz, H4), 6.92 (8H, br s, H3). 13C NMR
(126 MHz, CDCl3): d 68.65 (C6), 113.73 (C4), 117.59 (C8), 132.54 (C3), 133.34
(C7), 136.98 (C2), 138.42 (C1), 156.85 (C5). ESI-MS: found MH+ = 557.2685;
13. (a) Kelemu, S. W.; Steel, P. J. CrystEngComm 2013, 15, 9064; (b) Kelemu, S. W.;
Steel, P. J. CrystEngComm 2013, 15, 9072; (c) Kelemu, S. W.; Fitchett, C. M.;
Polson, M. I. J.; Wikaira, J. L.; Steel, P. J. J. Organomet. Chem. 2014, 749, 129.
14. Data for 4: yield 63%. Mp 127–129 °C. 1H NMR (400 MHz, CDCl3): d 4.51 (4H, d,
J = 5.1 Hz, H11, H16), 4.76 (2H, d, J = 4.3 Hz, H17), 5.51 (1H, d, J = 17.2 Hz,
H19b), 5.41 (2H, d, J = 17.2 Hz, H13b, H14b), 5.35 (1H, d, J = 10.5 Hz, H19a),
5.29 (2H, d, J = 10.6 Hz, H13a, H14a), 6.14–6.19 (1H, m, H18), 6.03–6.11 (2H, m,
H12, H15), 6.78–6.80 (4H, m, H1, H10), 6.89 (1H, s, H8), 7.00–7.02 (4H, m, H2,
H9), 7.07 (1H, d, J = 9.0 Hz, H4), 7.19 (1H, d, J = 8.6 Hz, H7), 7.47 (1H, d,
J = 9.4 Hz, H3), 8.06 (1H, s, H5), 8.56 (1H, d, J = 9.0 Hz, H6). 13C NMR (126 MHz,
CDCl3): d 68.71, 68.73, 69.10, 104.76, 111.29, 113.82, 113.97, 115.78, 115.88,
115.86, 117.68, 117.71, 117.94, 123.88, 124.59, 126.02, 129.52, 131.44, 131.89,
132.14, 132.22, 132.29, 133.30, 133.34, 134.04, 134.32, 137.71, 154.27, 156.97,
156.98, 157.28. IR (cmꢀ1): 3093, 2870, 1716, 1647, 1608, 1575, 1506, 1456,
1421, 1281, 1173, 1107, 1013, 992, 916, 866, 828, 795, 777, 631. ESI-MS: found
MH+ = 515.2224; C35H31O4 requires MH+ = 515.2217. Elem. Anal. Found: C,
78.97; H, 5.81. Calcd. for C35H30O4ꢁH2O: C, 78.92; H, 6.06.
C
38H37O4 requires MH+ = 557.2686. IR (cmꢀ1): 3022, 2987, 2879, 2734, 2525,
1893, 1647, 1606, 1572, 1500, 1454, 1407, 1380, 1284, 1244, 1173, 1113, 996,
928, 863, 837, 800, 767, 745. Elem. Anal. Found: C, 82.17; H, 6.59. Calcd. for
C
38H36O4: C, 81.99; H, 6.52.
7
4
O
O
O
3
8
5
6
1
2
O
OH
12
10
O
O
13a
13b
7
6
10. Crystal data for 2: C38H36O4, FW 556.67, monoclinic, space group P21/n,
8
3
9
2
11
a = 9.2476(3),
b = 24.8457(9),
c = 13.2688(5) Å,
b = 99.980(2)°,
) = 0.079 mmꢀ1
radiation),
I).
V = 3002.55(18) Å3, F(000) = 1184, Z = 4, T = ꢀ158 °C,
l(MoK
a
,
Dcalcd = 1.231 g cmꢀ3, 2hmax 54° (ApexII CCD area detector, MoK
a
5
19b
19a
14b
14a
GOF = 1.12, wR(F2) = 0.1386 (all 6433 data), R = 0.0620 (5253 data with I > 2
r
17
16
11. Yield 65%. Mp 95–97 °C. 1H NMR (500 MHz, CD3CN): d 4.51 (4H, d, J = 5.0 Hz),
4.79 (2H, d, J = 5.5 Hz), 5.25–5.52 (6H, m), 6.02–6.10 (2H, m), 6.13–6.20 (1H,
m), 6.78–6.82 (5H, m), 7.02–7.08 (5H, m), 7.17 (1H, d, J = 9.5 Hz), 7.31 (1H, d,
J = 9.0 Hz), 8.11 (1H, s), 8.65 (1H, d, J = 9.5 Hz). IR (cmꢀ1): 3093, 2870, 1611,
1527, 1497, 1454, 1424, 1367, 1327, 1281, 1225, 1197, 1178, 1042, 830, 780,
617. ESI-MS: Found MAg+ = 621.1201; C35H30O4Ag requires MAg+ = 621.1190.
12. Crystal data for the silver complex of 4: C70H64Ag3Cl3O22, FW 1687.17, triclinic,
O
4
1
18
15
15. Dyker, G.; Kellner, A. Tetrahedron Lett. 1994, 35, 7633.
16. Wadumethrige, S. H.; Rathore, R. Org. Lett. 2008, 10, 5139.
17. Gregg, D. J.; Ollagnier, C. M. A.; Fitchett, C. M.; Draper, S. M. Chem. Eur. J. 2006,
12, 3043.
18. Plieninger, H.; Ege, G.; Ullah, I. Chem. Ber. 1962, 96, 1610.
19. Li, C.-W.; Wang, C.-I.; Liao, H.-Y.; Chaudhuri, R.; Liu, R.-S. J. Org. Chem. 2007, 72,
9203.
space
= 100.618(6),
F(000) = 852, Z = 1, T = ꢀ153 °C,
2hmax 135° (Agilent Supernova area detector, CuK
wR(F2) = 0.1514 (all 5991 data), R = 0.0564 (4724 data with I > 2
group
P-1,
b = 106.646(6),
(CuKa ,
) = 8.811 mmꢀ1, Dcalcd = 1.687 g cmꢀ3
a = 9.4014(8),
b = 12.8095(11),
c = 104.621(7)°,
c = 15.4812(9) Å,
a
V = 1660.9(2) Å3,
l
a
radiation), GOF = 1.028,
I).
20. Kelemu, S. W. Ph.D. Thesis, University of Canterbury, 2013.
r