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Cross-metathesis of allylcarboranes with O-allylcyclodextrins

Ivan Šnajdr1, Zbyněk Janoušek2, Jindřich Jindřich1 and Martin Kotora1
1Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Praha 2, Czech Republic
2Institute of Inorganic Chemistry of the Academy of Science, v.v.i., Husinec-Řež 1001, 250 68 Řež, Czech Republic
Email of corresponding author Corresponding author email     
Guest Editor: K. Grela
Beilstein J. Org. Chem. 2010, 6, 1099–1105.
doi:10.3762/bjoc.6.126
 
 
 
 

Abstract

Cross-metathesis between allylcarboranes and O-allylcyclodextrins was catalyzed by Hoveyda–Grubbs 2nd generation catalyst in toluene. The corresponding carboranyl-cyclodextrin conjugates were isolated in 15–25% yields.

Keywords: carborane; catalysis; cross-metathesis; cyclodextrin; ruthenium

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Introduction

Cross-metathesis of two different alkenes constitutes an efficient and powerful tool for synthesis of various unsymmetrically substituted alkenes. This procedure has found enormous application in organic synthesis of various types of molecules such as natural and biologically active compounds [1]. One of the key aspects of this methodology, which is responsible for a high cross-metathesis selectivity, is a proper choice of a suitable ruthenium catalyst [2,3]. Efficacy of the cross-metathesis procedure has prompted also us to investigate hitherto unexplored combinations of two different alkenes. Recently, we have shown that metathesis of various terminal alkenes with perfluoroalkylpropenes constitutes a simple and efficient approach for the synthesis of wide array of perfluoroalkylated compounds [4]. This methodology was then applied for the synthesis of perfluoroalkylated analogs of brassinosteroids [5], 17α-perfluoroalkylestradiols [6], perfluoroalkylcyclodextrins [7], and perfluoroalkylcarboranes [8]. Successful execution of these reactions prompted us to study also cross-metathesis of allylcarboranes with O-allylcyclodextrins as a route to carborane-cyclodextrin conjugates. Herein, we report our preliminary results.

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Results and Discussion

Although studies on the inclusion of carboranes into cyclodextrins have previously been reported [9-13], a synthesis of cyclodextrin-carborane conjugates connected by a linker has not been, to the best of our knowledge, described. Since carboranes are of potential interest for various applications in medicine (e.g. boron neutron capture therapy for cancer, radionuclide diagnostics and therapy, and related fields [14-17], whilst some carboranes possess antiviral activity [18,19]), consequently, there is considerable interest in the synthesis of water soluble carborane derivatives. One strategy to access such compounds is based on the synthesis of carborane conjugates bearing a water-soluble moiety. With this in mind, we envisioned that this concept could be realized by the synthesis of carborane-cyclodextrin conjugates by the means of cross-metathesis between readily available allycarboranes and O-allylcyclodextrins (Figure 1).

[1860-5397-6-126-1]
Figure 1: Starting allylcarboranes 1a1c and O-allylcyclodextrins 2a2c.

The preparation of the starting allylcarboranes, i.e., 1-allyl-1,2-C2B10H11 1a [20], 8,8’-allyl-S-(C2B9H11)2Co 1b [21], and 8,8’-allyl-S2-(C2B9H11)2Co 1c [21], was carried out according to the previously reported procedures [8]. O-Allylcyclodextrins 2 were prepared by allylation of β-cyclodextrins under various reaction conditions (2I-O-allyl-β-cyclodextrin for 2a [22], 3I-O-allyl-β-cyclodextrin for 2b [23], and 6I-O-allyl-β-cyclodextrin for 2c) followed by peracetylation [7,24].

At the outset cross-metathesis of allylcarborane 1a with 2I-O-allylcyclodextrin 2a and various ruthenium-carbene complexes (10 mol %) in dichloromethane was carried out to assess the most suitable catalyst (for cross-metatheses involving carboranes, see: [25,26]). However, when the reaction was carried out in the presence of any of the following catalysts, Grubbs 1st, Grubbs 2nd, or Hoveyda–Grubbs 1st generation, no cross-metathesis products were obtained. Only catalysis by Hoveyda–Grubbs 2nd generation catalyst gave the desired product 3 in 14% yield. The suitability of Hoveyda–Grubbs 2nd generation catalyst for cross-metathesis reactions was consistent with the previously observed results [5-8]. Further tuning of the reaction conditions showed that the best yields were obtained by carrying out the reaction in toluene at 120 °C for 16 h (Scheme 1). Interestingly, when the reactions were carried out in CH2Cl2 (40 °C) the yields of the corresponding products were lower by 5–10%.

[1860-5397-6-126-i1]
Scheme 1: Cross-metathesis of allylcarboranes 1 and O-allylcyclodextrins 2.

Cross-metatheses of various allylcarboranes 1 and O-allylcyclodextrins 2 were then carried out. In general, the reactions proceeded to give the expected products without any problems (Table 1). Thus, the cross-metathesis of 1a with 2a, 2b, and 2c furnished the corresponding carboranylcyclodextrins 3aa, 3ab, and 3ac in 24, 17, and 15% isolated yields, respectively. In an analogous manner the cross-metathesis reactions of 1b with 2a and 2c gave the carboranylcyclodextrins 3ba and 3bc in 20 and 19% yields, respectively. Finally, the reactions of the cyclodextrin derivatives 2a2c with 1c afforded the corresponding carboranylcyclodextrins 3ca, 3cb, and 3cc in 18, 19 and 20% isolated yields, respectively. It is also of note to mention here the impressive E-selectivity of the cross-metathesis reactions, which has also been observed in other metathetical reactions with alkenylcyclodextrins derivatives [27] and can be explained by several factors [28]. Firstly, by a chelation of the intermediate Ru-carbene complex to the oxygen atoms of the cyclodextrin which results in a conformationally rigid intermediate and secondly, by a steric effect of the bulky carborane moiety. Although it may appear that the isolated yields are not high, conversions were in the range of ~50%. Isolation and purification of the products was a tedious task and the isolated yields we obtained represent the amounts of analytically pure compounds. It has been reported that low yields and conversions could be explained by isomerization of terminal to internal double bonds in both reactants (e.g., isomerization of allyl ethers to vinyl ethers [29-31] and allylcarboranes to propenylcarboranes [25]) and thus decreasing the reactant activity. However, NMR analysis of compounds isolated from the reaction mixtures revealed only the presence of the starting material and products, thus the low conversions could be attributed to deactivation of the catalysts by other routes. A similar effect has been also been observed in other cross-metathesis of various O-alkenylcyclodextrins which required the use of large amounts of catalyst [32,33]. Attempts to carry out the reaction with free (unprotected) O-allylcyclodextrins in dichloromethane or toluene has not so far resulted in the formation of any of the expected products, presumably because of their insolubility in the aforementioned solvents. To overcome the problem of the solubility of free O-allylcyclodextrins, the reaction was carried out in water in the presence of surfactant (SDS – sodium dodecyl sulfate), however, cross-metathesis did not occur.

Table 1: The prepared carborane-cyclodextrin conjugates 3.
ReactantsProductYield (%)a
1a2a[Graphic 1]3aa24
 2b[Graphic 2]3ab17
 2c[Graphic 3]3ac15
1b2a[Graphic 4]3ba20
 2c[Graphic 5]3bc19
1c2a[Graphic 6]3ca18
 2b[Graphic 7]3cb19
 2c[Graphic 8]3cc20
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Conclusion

The results described above clearly indicate that the cross-metathesis of allylcarboranes and O-allylcyclodextrins catalyzed by Hoveyda–Grubbs 2nd generation catalyst provides a simple and straightforward method for the synthesis of cyclodextrin-carborane conjugates. The high boron content and the presence of a water soluble moiety (after removal of the protecting groups) suggest that the compounds may have potential for use in medical applications.

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Experimental

General procedure for metathesis of allylcyclodextrins with allylcarboranes. The Hoveyda–Grubbs 2nd generation catalyst (3.13 mg, 0.005 mmol) was added under an argon atmosphere to a mixture of an allylcyclodextrin (0.07 mmol) and an allylcarborane (0.05 mmol) in toluene (5 mL). The resulting solution was stirred at 110 °C overnight. Removal of the solvent under reduced pressure gave a brown residue that was purified by column chromatography (85/15 MeOH/H2O) on C18-reversed phase.

Per-O-acetyl-2I-O-[4-(1,2-dicarbadodecaboran-1-yl)-but-2-en-1-yl]-β-cyclodextrin (3aa). The compound was prepared from 2a (0.15 g, 0.07 mmol) and 1a (15 mg, 0.05 mmol). Column chromatography gave the title compound, 0.041 g (24%), as a white powder: m. p. 188–190 °C; IR (KBr) [Graphic 9] = 2591, 1747, 1371, 1236, 1044 cm−1; 1H NMR (300 MHz, CDCl3): δ = 6.08–6.02 (m, 1 H, H-2’), 5.66–5.58 (m, 1 H, H-3’), 5.46–5.15 (m, 7 H, 7 × H-3), 5.13–4.92 (m, 7 H, 7 × H-1), 4.86–4.70 (m, 6 H, 6 × H-2), 4.61–4.43 (m, 6 H, 6 × H-6), 4.39–3.82 (m, 17 H, 8 × H-6, 7 × H-5, 2 × H-1’), 3.78–3.53 (m, 9 H, 7 × H-4, 2 × H-4’), 3.34 (d, J = 7.0 Hz, 1 H, H-2I), 2.97 (s, 1 H, Ccarb-H), 2.11–1.97 (m, 60 H, 20 × CH3); 13C NMR (100 MHz, CDCl3): δ = 171.15–169.71 (20 × C=O), 132.28 (C-2’), 126.69 (C-3’), 98.35–97.06 (7 × C-1), 78.05–76.42 (7 × C-4), 74.19 (C-1’), 72.29–69.66 (7 × C-2, 7 × C-3, 7 × C-5), 63.10–62.85 (7 × C-6), 60.34 (2 × Ccarb), 40.54 (C-4’), 21.56-21.02 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = −3.29 (s, 1 B, B-9), −6.45 (s, 1 B, B-12), −10.14 (s, 2 B, B-8, B-10), −12.21 (s, 2 B, B-4, B-5), −13.47 (s, 4 B, B-3, B-6, B-7, B-11); MS (EI, m/z (rel.%)) 1108.7 (80), 1010.5 (19), 799.0 (12), 516.9 (14), 456.8 (25), 374.0 (29), 242.3 (100), 228.6 (56), 168.9 (41); HR-MS (ESI) calcd. for C88H126O55B10: 1108.3925, found 1108.3954 (C88H126O5510B2B8Na2).

Per-O-acetyl-3I-O-[4-(1,2-dicarbadodecaboran-1-yl)-but-2-en-1-yl]-β-cyclodextrin (3ab). The compound was prepared from 2b (0.15 g, 0.07 mmol) and 1a (15 mg, 0.05 mmol). Column chromatography gave the title compound, 0.029 g (17%), as a white powder: m. p. 198–201 °C; IR (KBr): [Graphic 9] = 2593, 1747, 1369, 1237, 1043 cm−1; 1H NMR (400 MHz, CDCl3): δ = 5.91–5.70 (m, 1 H, H-2’), 5.60–5.50 (m, 1 H, H-3’), 5.49–5.28 (m, 6 H, H-3), 5.24–5.05 (m, 7 H, H-1), 4.89–4.66 (m, 8 H, 7 × H-4, 1 × H-1’), 4.66–3.64 (m, 31 H, 14 × H-6, 1 × H1’, 2 × H-4’, 7 × H-5, 7 × H-4), 3.23–3.13 (m, 1 H, H-3I), 2.84 (bs, 1 H, Ccarb-H), 2.20–1.95 (m, 60 H, 20 × CH3); 13C NMR (100 MHz, CDCl3): δ = 170.76–170.04 (20 × C=O), 133.74 (C-2’), 126.51 (C-3’), 97.41–96.70 (7 × C-1), 77.68–75.86 (7 × C-4), 72.42–69.46 (7 × C-2, 7 × C-3, 7 × C-5), 62.91–62.18 (7 × C-6), 60.57 (2 × Ccarb), 40.31(C-4’), 21.14–20.87 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = −3.32 (s, 1 B, B-9), −6.47 (s, 1 B, B-12), −10.12 (s, 2 B, B-8, B-10), −12.02 (s, 2 B, B-4, B-5), −13.99 (s, 4 B, B-3, B-6, B-7, B-11); MS (EI, m/z (rel.%)): 1108.6 (100), 917.4 (19), 802.8 (20), 690.9 (18), 469.4 (42), 413.2 (65), 370.1 (96), 301.1 (75); HR-MS (ESI) calcd. for C88H126O55B10 1108.3925, found 1108.3957 (C88H126O5510B2B8Na2).

Per-O-acetyl-6I-O-[4-(1,2-dicarbadodecaboran-1-yl)-but-2-en-1-yl]-β-cyclodextrin (3ac). The compound was prepared from 2c (0.15 g, 0.07 mmol) and 1a (15 mg, 0.05 mmol). Column chromatography gave the title compound,0.026 g (15%), as a white powder: m. p. 194–197 °C; IR (KBr): [Graphic 9] = 2917, 2848, 1747, 1370, 1235, 1044 cm−1; 1H NMR (400 MHz, CDCl3): δ = 5.91–5.82 (m, 1 H, H-2’), 5.75–5.65 (m, 1 H, H-3’), 5.42–5.00 (m, 14 H, 7 × H-3, 7 × H-1), 4.91–4.68 (m, 7 H, 7 × H-2), 4.64–4.42 (m, 5 H, 5 × H-6), 4.40–3.94 (m, 17 H, 2 × H-1’, 5 × H-5, 8 × H-6, 2 × H-4’), 3.90–3.82 (m, 2 H, 2 × H-5), 3.80–3.56 (m, 8 H, 1 × H-6I, 7 × H-4), 2.96 (bs, 1 H, Ccarb-H), 2.17–1.97 (m, 60 H, 20 × CH3); 13C NMR (100 MHz, CDCl3): δ = 171.10–169.81 (20 × C=O), 134.05 (C-2’), 126.31 (C-3’), 97.45–96.64 (7 × C-1), 77.69–76.30 (7 × C-4), 71.94–69.79 (7 × C-2, 7 × C-3, 7 × C-5, C-1’), 68.12 (C-6I), 63.02–62.71 (6 × C-6), 60.18 (2 × Ccarb), 40.08 (C-4’), 21.87–21.16 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = −3.27 (s, 1 B, B-9), −6.69 (s, 1 B, B-12), −10.12 (s, 2 B, B-8, B-10), −12.04 (s, 2 B, B-4, B-5), −13.94 (s, 4 B, B-3, B-6, B-7, B-11); MS (EI, m/z (rel.%)): 1108.5 (52), 1010.1 (62), 928.6 (51), 909.0 (60), 667.1 (31), 351.3 (57), 307.3 (100); HR-MS (ESI) calcd. for C88H126O55B10: 1108.3925, found 1108.3955 (C88H126O5510B2B8Na2).

Per-O-acetyl-2I-O-{4-{8,8’-μ-(sulfido)-[3,3’-commo-cobalt(III)-bis-(1,2-dicarbaundecaborate)]-8-yl}but-2-en-1-yl}-β-cyclodextrin (3ba). The compound was prepared from 2a (0.15 g, 0.07 mmol) and 1b (20 mg, 0.05 mmol). Column chromatography gave the title compound, 0.023 g (18%), as an orange powder: m. p. 207–209 °C; IR (KBr): [Graphic 9] = 2575, 1746, 1371, 1236, 1044 cm−1. 1H NMR (600 MHz, CDCl3): δ = 5.75 (dt, J = 20.4, 5.4 Hz, 1 H, H-2’), 5.65–5.58 (m, 1 H, H-3’), 5.43–5.13 (m, 7 H, 7 × H-3), 5.12–4.91 (m, 6 H, 6 × H-1), 4.86 (d, J = 3.6 Hz, 1 H, H-1I), 4.98–4.62 (m, 6 H, 6 × H-2), 4.56–4.38 (m, 6 H, 6 × H-6), 4.30–3.87 (m, 17 H, 8 × H-6, 7 × H-5, 2 × H-1’), 3.72–3.50 (m, 9 H, 7 × H-4, 2 × H-4’), 3.46–3.34 (m, 4 H, Ccarb-H), 3.24 (dd, J = 3.0, 9.6 Hz, 1 H, H-2I), 2.09–1.97 (m, 60 H, 20 × CH3); 13C NMR (150 MHz, CDCl3): δ = 170.81–169.37 (20 × C=O), 134.55 (C-2’), 122.80 (C-3’), 98.16–96.58 (7 × C-1), 78.05–76.17 (7 × C-4), 71.03–69.54 (7 × C-2, 7 × C-3, 7 × C-5, C-1’), 62.85–62.41 (7 × C-6), 49.33–48.66 (4 × Ccarb), 42.02 (C-4’), 20.99–20.22 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = 1.26 (bs, 2 B, B-8, B-8’), −4.70 (bs, 2 B, B-10, B-10’), −(6.00–11.72) (m, 12 B, B-4, B-4’, B-5, B-5’, B-7, B-7’, B-9, B-9’, B-11, B-11’, B-12, B-12’), −14.68 (bs, 2 B, B-6, B-6’); MS (EI, m/z (rel.%)): 1214.4 (100), 1010.3 (10), 413.3 (68), 391.3 (10), 307.2 (52); HR-MS (ESI) calcd. for C90H135O5510B3B15CoNa2S: 1213.9194, found 1213.9233.

Per-O-acetyl-6I-O-{4-{8,8’-μ-(sulfido)-[3,3’-commo-cobalt(III)-bis-(1,2-dicarbaundecaborate)]-8-yl}but-2-en-1-yl}-β-cyclodextrin (3bc). The compound was prepared from 2c (0.15 g, 0.07 mmol) and 1b (20 mg, 0.05 mmol). Column chromatography gave the title compound, 0.028 g (22%), as an orange powder: m. p. 188–191 °C; IR (KBr): [Graphic 9] = 2955, 2575, 1747, 1370, 1237, 1046 cm−1; 1H NMR (600 MHz, CDCl3): δ = 5.90 (dt, J = 15.1, 5.1 Hz, 1 H, H-2’), 5.78–5.68 (m, 1 H, H-3’), 5.40–5.19 (m, 7 H, 7 × H-3), 5.17–5.02 (m, 7 H, 7 × H-1), 4.86–4.69 (m, 7 H, 7 × H-2), 4.63–4.42 (m, 5 H, 5 × H-6), 4.36–3.96 (m, 17 H, 2 × H-1’, 2 × H-4’, 5 × H-5, 8 × H-6), 3.90–3.85 (m, 2 H, 2 × H-5), 3.78–3.65 (m, 10 H, 1 × H-6I, 7 × H-4, 2 × Ccarb-H), 3.48 (bs, 1 H, Ccarb-H), 3.42 (bs, 1 H, Ccarb-H), 2.16–1.98 (m, 60 H, 20 × CH3); 13C NMR (100 MHz, CDCl3): δ = 171.10–169.80 (20 × C=O), 134.85 (C-2’), 122.80 (C-3’), 97.46–96.77 (7 × C-1), 77.69–76.21 (7 × C-4), 72.02–69.63 (7 × C-2, 7 × C-3, 7 × C-5, C-1’), 68.28 (C-6I), 62.99–62.77 (6 × C-6), 49.93–49.27 (4 × Ccarb), 42.71 (C-4’), 21.15–20.58 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = 1.39 (bs, 2 B, B-8, B-8’), −4.58 (bs, 2 B, B-10, B-10’), −(5.84–11.21) (m, 12 B, B-4, B-4’, B-5, B-5’, B-7, B-7’, B-9, B-9’, B-11, B-11’, B-12, B-12’), −14.92 (bs, 2 B, B-6, B-6’); MS (EI, m/z (rel.%)): 1214.1 (100), 1010.3 (10), 414.3 (52), 360.3 (10), 307.2 (96); HR-MS (ESI) calcd. for C90H135O5510B3B15CoNa2S: 1213.9194, found 1213.9234.

Per-O-acetyl-2I-O-{4-{8,8’-μ-(disulfido)-[3,3’-commo-cobalt(III)-bis-(1,2-dicarbaundecaborate)]-8-yl}but-2-en-1-yl}-β-cyclodextrin (3ca). The compound was prepared from 2a (0.15 g, 0.07 mmol) and 1c (20 mg, 0.05 mmol). Column chromatography gave the title compound, 0.026 g (20%), as a red powder: m. p. 188–191 °C; IR (KBr): [Graphic 9] = 2581, 1746, 1371, 1236, 1043 cm−1; 1H NMR (600 MHz, CDCl3): δ = 6.04–5.95 (m, 1 H, H-2’), 5.72–5.63 (m, 1 H, H-3’), 5.34–5.16 (m, 7 H, 7 × H-3), 5.10–4.97 (m, 6 H, 6 × H-1), 4.96 (t, J = 3.6 Hz, 1 H, H-1I), 4.84–4.76 (m, 6 H, 6 × H-2), 4.58–4.47 (m, 7 H, 7 × H-6), 4.37–4.00 (m, 18 H, 2 × H-1’, 2 × H-4’, 7 × H-5, 7 × H-6), 3.74–3.55 (m, 8 H, 6 × H-4, 2 × Ccarb-H), 3.51–3.45 (m, 1 H, Ccarb-H), 3.37–3.31 (m, 2 H, 1 × H-2I, 1 × Ccarb-H), 2.12–1.95 (m, 60 H, 20 × CH3); 13C NMR (150 MHz, CDCl3): δ = 171.11–169.56 (20 × C=O), 138.15 (C-2’), 121.0 (C-3’), 98.27–96.81 (7 × C-1), 77.97–76.38 (7 × C-4), 72.24–69.43 (7 × C-2, 7 × C-3, 7 × C-5, C-1’), 63.06–62.62 (7 × C-6), 51.99 (Ccarb), 50.92 (Ccarb), 50.85 (Ccarb), 49.36–49.08 (C-4’, Ccarb), 21.24–21.01 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = 21.13 (bs, 2 B, B-8, B-8’), 0.56 (bs, 2 B, B-10, B-10’), −(1.91–10.86) (m, 12 B, B-4, B-4’, B-5, B-5’, B-7, B-7’, B-9, B-9’, B-11, B-11’, B-12, B-12’), −15.30 (bs, 2 B, B-6, B-6’); MS (EI, m/z (rel.%)): 2436.4 (60), 2037.3 (10), 1272.7 (10), 1230.2 (100), 1030.6 (16), 1010.1 (10), 307.1 (61); HR-MS (ESI) calcd. for C90H135O5510B6B12CoNa2S2: 1228.4109, found 1228.4128.

Per-O-acetyl-3I-O-{4-{8,8’-μ-(disulfido)-[3,3’-commo-cobalt(III)-bis-(1,2-dicarbaundecaborate)]-8-yl}but-2-en-1-yl}-β-cyclodextrin (3cb). The compound was prepared from 2b (0.15 g, 0.07 mmol) and 1c (20 mg, 0.05 mmol). Column chromatography gave the title compound, 0.029 g (25%), as a red powder: m. p. 201–203 °C; IR (KBr): [Graphic 9] = 2955, 2582, 1747, 1368, 1236, 1042 cm−1; 1H NMR (600 MHz, CDCl3): δ = 6.15–6.06 (m, 1 H, H-2’), 5.74–5.65 (m, 1 H, H-3’), 5.50–5.22 (m, 7 H, 7 × H-3), 5.15–4.99 (m, 6 H, 6 × H-1), 4.85–4.61 (m, 8 H, 7 × H-4, 1 × H-1’), 4.60–3.85 (m, 25 H, 14 × H-6, 2 × H1’, 2 × H-4’, 7 × H-5), 3.84–3.49 (m, 9 H, 7 × H-4, 2 × Ccarb-H), 3.37 (bs, 1 H, Ccarb-H), 3.34 (bs, 1 H, Ccarb-H), 2.12–1.93 (m, 60 H, 20 × CH3); 13C NMR (150 MHz, CDCl3): δ = 170.86–169.86 (20 × C=O), 139.90 (C-2’), 119.35 (C-3’), 97.80–96.37 (7 × C-1), 77.89–75.67 (7 × C-4), 73.50 (C-1’), 72.23–69.05 (7 × C-2, 7 × C-3, 7 × C-5), 62.94–62.28 (7xC-6), 51.82 (Ccarb), 51.07 (Ccarb), 50.83 (Ccarb), 49.63–49.42 (C-4’, Ccarb), 21.09–21.00 (20 × CH3); 11B NMR (128 MHz, CDCl3): δ = 20.96 (bs, 2 B, B-8, B-8’), 0.54 (bs, 2 B, B-10, B-10’), −(1.99–10.87) (m, 12 B, B-4, B-4’, B-5, B-5’, B-7, B-7’, B-9, B-9’, B-11, B-11’, B-12, B-12’), −15.42 (bs, 2 B, B-6, B-6’); MS (EI, m/z (rel.%)): 2438.8 (41), 2250.9 (10), 2037.7 (15), 1229.9 (50), 1030.8 (33), 307.2 (100); HR-MS (ESI) calcd. for C90H135O5510B6B12CoNa2S2: 1228.4109, found 1228.4127.

Per-O-acetyl-6I-O-{4-{8,8’-μ-(disulfido)-[3,3’-commo-cobalt(III)-bis-(1,2-dicarbaundecaborate)]-8-yl}but-2-en-1-yl}-β-cyclodextrin (3cc). The compound was prepared from 2c (0.15 g, 0.07 mmol) and 1c (20 mg, 0.05 mmol). Column chromatography gave the title compound, 0.022 g (19%), as a red powder: m. p. 198–200 °C; IR (KBr): [Graphic 9] = 2578, 1747, 1370, 1236, 1045 cm−1; 1H NMR (600 MHz, CDCl3): δ = 6.07 (dt, J = 15.0, 5.0 Hz, 1 H, H-2’), 5.77–5.70 (m, 1 H, H-3’), 5.40–5.21 (m, 7 H, 7 × H-3), 5.16–5.05 (m, 7 H, 7 × H-1), 4.86–4.69 (m, 7 H, 7 × H-2), 4.63–4.52 (m, 4 H, 4 × H-6), 4.46 (dd, J = 10.8, 3.5 Hz, 1 H, 1 × H-6), 4.41–4.03 (m, 17 H, 2 × H-1’, 2 × H-4’, 5 × H-5, 8 × H-6), 3.93–3.89 (m, 2 H, 2 × H-5), 3.87 (m, 2 H, 2 × H-4), 3.75–3.62 (m, 8 H, 1 × H-6I, 5 × H-4, 2 × Ccarb-H), 3.49 (bs, 1 H, Ccarb-H), 3.34 (bs, 1 H, Ccarb-H), 2.16–2.00 (m, 60 H, 20 × CH3); 13C NMR (150 MHz, CDCl3): δ = 171.13–169.51 (20 × C=O), 137.95 (C-2’), 120.88 (C-3’), 97.38–96.55 (7 × C-1), 77.82–76.21 (7 × C-4), 71.86–68.37 (7 × C-2, 7 × C-3, 7 × C-5, C-1’), 68.37 (C-6I), 62.93–62.65 (6 × C-6), 52.23 (Ccarb), 51.68 (Ccarb), 50.99 (Ccarb), 49.64–49.21 (C-4’, Ccarb), 21.07–20.98 (20 × CH3); 11B NMR (128 MHz, CDCl3) δ 21.66 (bs, 2 B, B-8, B-8’), 0.18 (s, 1 B, B-10 or B-10’), −1.02 (s, 1 B, B-10 or B-10’), −(1.93-10.95) (m, 12 B, B-4, B-4’, B-5, B-5’, B-7, B-7’, B-9, B-9’, B-11, B-11’, B-12, B-12’), −15.63 (s, 2 B, B-6, B-6’); MS (EI, m/z (rel.%)): 2437.8 (23), 2085.6 (11), 1229.9 (20), 1010.1 (15), 528.1 (10), 307.2 (100); HR-MS (ESI) calcd. for C90H135O5510B6B12CoNa2S2: 1228.4109, found 1228.4119.

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Supporting Information

Supporting Information File 1: Experimental details and characterisation data of peracetylated cyclodextrins 2a, 2b and 2c.
Format: PDF   Size: 176.6 KB   Download

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Acknowledgements

This work was supported by the Ministry of Education, Youth, and Sports (project No. MSM0021620857) and the Academy of Sciences of the Czech Republic (project No. KAN 200200651).

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References

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  31. Finnegan, D.; Seigal, B. A.; Snapper, M. L. Org. Lett. 2006, 8, 2603–2606. doi:10.1021/ol060918g
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Figure 1: Starting allylcarboranes 1a1c and O-allylcyclodextrins 2a2c. Move  Close
Scheme 1: Cross-metathesis of allylcarboranes 1 and O-allylcyclodextrins 2. Move  Close
Table 1: The prepared carborane-cyclodextrin conjugates 3. Move  Close
ReactantsProductYield (%)a
1a2a[Graphic 1]3aa24
 2b[Graphic 2]3ab17
 2c[Graphic 3]3ac15
1b2a[Graphic 4]3ba20
 2c[Graphic 5]3bc19
1c2a[Graphic 6]3ca18
 2b[Graphic 7]3cb19
 2c[Graphic 8]3cc20
9.Grüner, B.; Holub, J.; Plešek, J.; Vaněk, T.; Votavová, H. J. Chromatogr., A 1998, 793, 249–256. doi:10.1016/S0021-9673(97)00904-7
10.Frixa, C.; Scobie, M.; Black, S. J.; Thompson, A. S.; Threadgill, M. D. Chem. Commun. 2002, 2876–2877. doi:10.1039/b209339a
11.Ohta, K.; Konno, S.; Endo, Y. Tetrahedron Lett. 2008, 49, 6525–6528. doi:10.1016/j.tetlet.2008.08.107
12.Ohta, K.; Konno, S.; Endo, Y. Chem. Pharm. Bull. 2009, 57, 307–310. doi:10.1248/cpb.57.307
13.Uchman, M.; Jurkiewicz, P.; Cígler, P.; Grüner, B.; Hof, M.; Procházka, K.; Matějíček, P. Langmuir 2010, 26, 6268–6275. doi:10.1021/la904047k
Go to references 9-13
14.Plešek, J. Chem. Rev. 1992, 92, 269–278. doi:10.1021/cr00010a005
15.Soloway, A. H.; Tjarks, W.; Barnum, B. A.; Rong, F.-G.; Barth, R. F.; Codogni, I. M.; Wilson, J. G. Chem. Rev. 1998, 98, 1515–1562. doi:10.1021/cr941195u
16.Hawthorne, M. F.; Maderna, A. Chem. Rev. 1999, 99, 3421–3434. doi:10.1021/cr980442h
17.Sivaev, I. B.; Bregadze, V. V. Eur. J. Inorg. Chem. 2009, 1433–1450. doi:10.1002/ejic.200900003
Go to references 14-17
7.Řezanka, M.; Eignerová, B.; Jindřich, J.; Kotora, M. Eur. J. Org. Chem. 2010, 6256–6262. doi:10.1002/ejoc.201000807
Go to reference 7
8.Eignerová, B.; Janoušek, Z.; Dračínský, M.; Kotora, M. Synlett 2010, 885–887.
Go to reference 8
5.Eignerová, B.; Slavíková, B.; Buděšínský, M.; Dračínský, M.; Klepetářová, B.; Šťastná, E.; Kotora, M. J. Med. Chem. 2009, 52, 5753–5757. doi:10.1021/jm900495f
Go to reference 5
6.Eignerová, B.; Sedlák, D.; Dračínský, M.; Bartůněk, P.; Kotora, M. J. Med. Chem. 2010, 53, 6947–6953. doi:10.1021/jm100563h
Go to reference 6
2.Bieniek, M.; Michrowska, A.; Usanov, D. L.; Grela, K. Chem.–Eur. J. 2008, 14, 806–818. doi:10.1002/chem.200701340
3.Vougioukalakis, G. C.; Grubbs, R. H. Chem. Rev. 2010, 110, 1746–1787. doi:10.1021/cr9002424
Go to references 2,3
4.Eignerová, B.; Dračínský, M.; Kotora, M. Eur. J. Org. Chem. 2008, 4493–4499. doi:10.1002/ejoc.200800230
Go to reference 4
1.Connon, S. J.; Blechert, S. Angew. Chem., Int. Ed. 2003, 42, 1900–1923. doi:10.1002/anie.200200556
Go to reference 1
5.Eignerová, B.; Slavíková, B.; Buděšínský, M.; Dračínský, M.; Klepetářová, B.; Šťastná, E.; Kotora, M. J. Med. Chem. 2009, 52, 5753–5757. doi:10.1021/jm900495f
6.Eignerová, B.; Sedlák, D.; Dračínský, M.; Bartůněk, P.; Kotora, M. J. Med. Chem. 2010, 53, 6947–6953. doi:10.1021/jm100563h
7.Řezanka, M.; Eignerová, B.; Jindřich, J.; Kotora, M. Eur. J. Org. Chem. 2010, 6256–6262. doi:10.1002/ejoc.201000807
8.Eignerová, B.; Janoušek, Z.; Dračínský, M.; Kotora, M. Synlett 2010, 885–887.
Go to references 5-8
25.Wei, X.; Carroll, P. J.; Sneddon, L. G. Organometallics 2006, 25, 609–621. doi:10.1021/om050851l
26.Simon, Y. C.; Ohm, C.; Zimny, M. J.; Coughlin, E. B. Macromolecules 2007, 40, 5628–5630. doi:10.1021/ma0709093
Go to references 25,26
7.Řezanka, M.; Eignerová, B.; Jindřich, J.; Kotora, M. Eur. J. Org. Chem. 2010, 6256–6262. doi:10.1002/ejoc.201000807
24.Jindřich, J.; Tišlerová, I. J. Org. Chem. 2005, 70, 9054–9055. doi:10.1021/jo051339c
Go to references 7,24
21.Janoušek, Z.; Plešek, J.; Heřmánek, S.; Baše, K.; Todd, L. J.; Wright, W. F. Collect. Czech. Chem. Commun. 1981, 46, 2818–2833.
Go to reference 21
8.Eignerová, B.; Janoušek, Z.; Dračínský, M.; Kotora, M. Synlett 2010, 885–887.
Go to reference 8
32.Chiu, S.-H.; Myles, D. C.; Garrell, R. L.; Stoddart, J. F. J. Org. Chem. 2000, 62, 2792–2796. doi:10.1021/jo9910381
33.Aime, S.; Gianolio, E.; Palmisano, G.; Robaldo, B.; Barge, A.; Boffa, L.; Cravotto, G. Org. Biomol. Chem. 2006, 4, 1124–1130. doi:10.1039/b517068k
Go to references 32,33
22.Jindrich, J.; Pitha, J.; Lindberg, B.; Seffers, P.; Harata, K. Carbohydr. Res. 1995, 266, 75–80. doi:10.1016/0008-6215(94)00251-A
Go to reference 22
23.Masurier, N.; Estour, F.; Lefèvre, B.; Brasme, B.; Masson, P.; Lafont, O. Carbohydr. Res. 2006, 341, 935–940. doi:10.1016/j.carres.2006.02.012
Go to reference 23
29.Schmidt, B. Eur. J. Org. Chem. 2003, 816–819. doi:10.1002/ejoc.200390124
30.Hong, S. H.; Sanders, D. P.; Lee, C. W.; Grubbs, R. H. J. Am. Chem. Soc. 2005, 127, 17160–17161. doi:10.1021/ja052939w
31.Finnegan, D.; Seigal, B. A.; Snapper, M. L. Org. Lett. 2006, 8, 2603–2606. doi:10.1021/ol060918g
Go to references 29-31
25.Wei, X.; Carroll, P. J.; Sneddon, L. G. Organometallics 2006, 25, 609–621. doi:10.1021/om050851l
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18.Cígler, P.; Kožíšek, M.; Řezáčová, P.; Brynda, J.; Otwinowski, Z.; Pokorná, J.; Plešek, J.; Grüner, B.; Dolečková-Marešová, L.; Máša, M.; Sedláček, J.; Bodem, J.; Kräusslich, H.-G.; Král, V.; Konvalinka, J. Proc. Natl. Acad. Sci. U. S. A. 2005, 102, 15394–15399. doi:10.1073/pnas.0507577102
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