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Synlett 2005(7): 1125-1128  
DOI: 10.1055/s-2005-865215
LETTER
© Georg Thieme Verlag Stuttgart · New York

Tris-Annelated Benzenes Selectively Perfunctionalized on One Side Only: Hexachlorobenzotrinorbornadiene as a Versatile Scaffold for the Construction of Molecular Domes

Giuseppe Borsato*a, Stefania Brussoloa, Marco Crismab, Ottorino De Lucchic, Vittorio Lucchini*a, Alfonso Zambona
a Dipartimento di Scienze Ambientali, Università Ca’ Foscari di Venezia, Dorsoduro 2137, 30123, Venezia, Italy
b Istituto di Chimica Biomolecolare, CNR, Sezione di Padova, via Marzolo 1, 35131, Padova, Italy
c Dipartimento di Chimica, Università Ca’ Foscari di Venezia, Dorsoduro 2137, 30123,Venezia, Italy
Fax: +39(041)2348584; e-Mail: gborsato@unive.it;
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Publication History

Received 21 January 2005
Publication Date:
14 April 2005 (online)

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Abstract

Well-defined, rigid molecular domes are obtained via substitution of the chlorine atoms of hexachlorobenzotrinorbornadiene syn-3, efficiently synthesized in 1:2 ratio along with its anti-isomer by CuTC-promoted cyclotrimerization of 3-bromo-2-tri­methylstannylnorbornadiene 8. The three dichlorovinyl functions at the edge of syn-3 are displaced by sulfur nucleophiles and Grignard reagents with Ni(II)Cl2dppe as catalyst, gaining the persubstituted vinyl sulfides 9 and 10, and persubstituted methyl 12 and phenylethynyl 13.

Key words

cyclotrimerization - cross-coupling - nucleophilic substitution - copper(I) 2-thiophenecarboxylate - dendrimers

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Cyclotrimerization Reaction. CuTC (23.39 g, 123 mmol) was added portionwise to a solution of 8 (33 g, 82 mmol) in 420 mL dry NMP and stirred at -15 °C. After 3 h the mixture was quenched with 10% aq NH3 and extracted with EtOAc (3 × 100 mL). The organic layers were dried over MgSO4 and concentrated in vacuo. The syn- and anti-isomers (11.7 g, 24.6 mol, 90%) were separated by FC (eluant: hexane-CCl4 1:1). The syn/anti ratio was 1:2. Compound syn-3: mp 274 °C (dec). 1H NMR (400 MHz, CDCl3): δ = 3.86 (6 H, H1 and H4, t, J = 1.8 Hz), 2.66 (3 H, H7s, dt, J = 7.6, 1.5 Hz), 2.24 (3 H, H7a, dt, J = 7.6, 1.8 Hz). 13C NMR (100 MHz, CDCl3): δ = 139.2 (6 C, C5 and C6), 136.9 (6 C, C2 and C3), 62.0 (3 C, C7), 53.8 (6 C, C1 and C4).
Compound anti-3: mp 215 °C (dec). 1H NMR (400 MHz, CDCl3): δ = 3.89 (2 H, H1 ′ and H4 ′, t, J = 1.8 Hz), 3.89 and 3.88 (4 H, H1 and H4, t, J = 1.8, Hz), 2.66 (2 H, H7s, dt, J = 7.6, 1.8 Hz), 2.65 (1 H, H7s ′, dt, J = 7.6, 1.8 Hz), 2.25 (1 H, H7a ′, dt, J = 7.6, 1.9 Hz), 2.24 (2 H, H7a, dt, J = 7.6, 1.9 Hz). 13C NMR (100 MHz, CDCl3): δ = 139.0, 138.7 and 138.5 (12 C, C5, C6, C5 ′ and C6 ′), 137.0, 136.7 and 136.5 (12 C, C2, C3, C2 ′ and C3 ′), 62.5 and 62.3 (6 C, C1, C4, C1 ′ and C4 ′), 58.9 (1 C, C7 ′) 53.8 (2 C, C7).

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CCDC 261321 contains the crystallographic data for syn-3. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

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Reaction of syn -3 with 1-Dodecanthiol.
A solution of dodecanthiol (260 µL, 1.07 mmol) in 5 mL of dry DMF was added portionwise to a solution of syn-3 (50 mg, 0.1 mmol) and NaH 60% (143 mg, 3.59 mmol) in 5 mL DMF. The mixture was stirred under argon 3 d at 110 °C, and then quenched with diluted HCl and extracted with Et2O (3 × 10 mL). The ethereal extracts were washed with 10% NaOH solution, dried over MgSO4 and concentrated in vacuo. The reaction crude was purified by FC (eluant: CH2Cl2-hexane, 1:9), giving 9 (60%) as brown oil. 1H NMR (400 MHz, CDCl3): δ = 3.95 (6 H, H1 and H4, t, J = 1.7 Hz), 2.90 and 2.72 (12 H, H8, t split in an AB system, J = 12.6, 7.6 Hz), 2.22 (3 H, H7s, dt, J = 7.5, 1.7 Hz), 2.10 (3 H, H7a, dt, J = 7.5, 1.7 Hz), 1.56 (12 H, H9, m), 1.43-1.34 (12 H, H10, m), 1.29-1.20 (96 H, CH2, m), 0.87 (18 H, CH3, t, J = 7.1 Hz). 13C NMR (100 MHz, CDCl3): δ = 144.2 (6 C, C2 and C3), 136.8 (6 C, C5 and C6), 61.6 (3 C, C7), 52.1 (6 C, C1 and C4), 32.5 (6 C, C8), 30.3 (6 C, C9), 29.8-29.5 (6 C, C10), 29.8-29.7 (48 C, CH2), 14.2 (6 C, CH3).

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Reaction of syn -3 with Thiophenol. MeONa was generated in situ by reaction of 5 mL dry MeOH and Na (27.5 mg, 1.2 mmol). The solvent was removed, thiophenol (0.125 mL, 1.2 mmol) and a solution of syn -3 (50 mg, 0.1 mmol) in NMP (5 mL) were added. The mixture was stirred 3 d at 150 °C and then the solvent removed at reduced pressure. The residue was diluted with EtOAc and washed 3 times with 10% NaOH solution. The organic layers were dried over MgSO4 and concentrated in vacuo. The reaction crude was purified by FC (eluant: EtOAc-hexane, 3:7); giving 10 (90%) as white solid and traces of 11 as a brown oil. Compound 10: 1H NMR (400 MHz, CDCl3): δ = 7.33 (12 H, H9, m), 7.21 (18 H, H10 and H11, m), 3.76 (6 H, H1 and H4, t, J = 1.6 Hz), 2.36 (3 H, H7s, dt, J = 7.7, 1.6 Hz), 2.09 (3 H, H7a, dt, J = 7.7, 1.6 Hz). 13C NMR (100 MHz, CDCl3): δ = 148.7 (6 C, C2 and C3), 137.6 (6 C, C5 and C6), 135.7 (6 C, C8), 129.8 (12 C, C9), 128.8 (12 C, C10), 126.3 (6 C, C11), 60.4 (3 C, C7), 53.0 (6 C, C1 and C4).
Compound 11: 1H NMR (400 MHz, CDCl3): δ = 7.42 (4 H, H9 ′, m), 7.37-7.35 (6 H, H10 ′ and H11 ′, m), 7.26 (6 H, H10 and H11, m), 7.21 (4 H, H9, m), 3.80 (2 H, H1, m), 3.79 (2 H, H4, m), 3.67 (2 H, H1 ′ and H4 ′, t, J = 1.9 Hz), 2.53 (1 H, H7s ′, dt, J = 7.5, 1.8 Hz), 2.36 (2 H, H7s, dt, J = 7.7, 1.6 Hz), 2.15 (2 H, H7a, dt, J = 7.7, 1.6 Hz), 2.08 (1 H, H7a ′, J = 7.5, 1.8 Hz). 13C NMR (100 MHz, CDCl3): δ = 150.2 (2 C, C2), 146.0 (2 C, C3), 139.6 (2 C, C2 ′ and C3 ′), 138.2 (2 C, C5), 137.9 (2 C, C6), 135.9 (2 C, C5 ′ and C6 ′), 135.8 (2 C, C8), 134.0 (2 C, C8 ′), 130.9 (4 C, C9 ′), 129.4 (6 C, C10 and C11), 129.0 (4 C, C9), 126.9 (6 C, C10 ′ and C11 ′), 53.7 (2 C, C1 ′ and C4 ′), 53.4 (2 C, C1), 53.7 (2 C, C4), 62.4 (1 C, C7 ¢), 59.6 (2 C, C7).

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Reaction of syn -3 with MeMgBr.
A 3 M solution of MeMgBr in Et2O (1 mL, 3 mmol), was added dropwise to a solution of syn-3 (100 mg, 0.22 mmol) in 5 mL dry THF at r.t. under argon, and then a catalytic amount of Ni(II)Cl2(dppe) was added portionwise. The brown solution was quenched after 1 d with sat. NH4Cl solution, extracted with Et2O (3 × 20 mL), the organic layers dried over MgSO4 and concentrated in vacuo, giving 12 (90%) as brown oil. 1H NMR (400 MHz, CDCl3): δ = 3.49 (6 H, H1 and H4, t, J = 1.7 Hz), 2.13 (3 H, H7s, dt, J = 6.9, 1.7 Hz), 1.93 (3 H, H7a, dt, J = 6.9, 1.7 Hz), 1.65 (18 H, CH3, s). 13C NMR (100 MHz, CDCl3): δ = 142.0 (6 C, C5 and C6), 137.2 (6 C, C2 and C3), 62.6 (3 C, C7), 52.6 (6 C, C1 and C4), 14.2 (6 C, CH3).

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Reaction of syn -3 with PhC≡CH.
A 1.15 M solution of MeMgBr in Et2O (4 mL, 4.6 mmol) was added dropwise to a solution of PhC≡CH (0.54 mL, 4.8 mmol) in 5 mL dry THF at -78 °C under argon. The thick white suspension was then allowed to warm to r.t., and then a solution of syn-3 (100 mg, 0.22 mmol) in 5 mL dry THF was added, followed by a catalytic amount of Ni(II)Cl2(dppe). The dark solution was refluxed for 3 d. Then other 40 equiv of the Grignard reagent were added. The mixture was warmed for 2 d, quenched with sat. NH4Cl and extracted with Et2O (3 × 20 mL). The organic layers were dried over MgSO4 and concentrated in vacuo. The reaction crude was purified by FC (eluant: toluene-hexane, 1:1), giving 13 (20%) as brown solid. 1H NMR (400 MHz, CDCl3): δ = 7.20 (12 H, H11, dd, J = 7.7, 1.3 Hz), 7.11 (6 H, H13, dt, J = 7.6, 1.6 Hz), 6.9 (12 H, H12, t, J = 7.8 Hz), 4.18 (6 H, H1 and H4, t, J = 1.7 Hz), 2.63 (3 H, H7a or H7s, dt, J = 7.7, 1.3 Hz), 2.31 (3 H, H7s or H7a, dt, J = 7.7, 1.2 Hz). 13C NMR (100 MHz, CDCl3): δ = 140.3 (6 C, C5 and C6 or C2 and C3), 137.1 (6 C, C5 and C6 or C2 and C3), 131.3 (12 C, C11), 128.0 (12 C, C12), 127.0 (6 C, C13), 123.3 (6 C, C10), 102.8 (6 C, C9), 85.1 (6 C, C8), 65.6 (3 C, C7), 53.0 (6 C, C1 and C4).