Selective Electrochemical Mono- and Polysilylation of Halothiophenes

Deffieux, Denis; Bonafoux, D.; Bordeau, M.; Biran, C.; Dunoguès, J.

doi:10.1021/om950605h

Cited by 20 publications

(9 citation statements)

References 24 publications

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“…The 1 H NMR spectrum was consistent with literature data for 8 prepared using an alternative method starting from 2,3-dibromothiophene. 82 2-(Trimethylsilyl)-3-n-hexylthiophene (9) n-Hexylmagnesium bromide (60 mL of a commercial 2.0 M solution in diethyl ether, 1.2 eq, 0.12 mol) was added over 3 h period to a mixture of 8 (0.10 mol, 23.52 g), catalyst NiCl 2 (dppp) (1.08 g, 2 mmol, 2 mol%), and anhydrous THF (100 mL). During the addition of the Grignard reagent the catalyst dissolved, the flask became warm to the touch, and precipitate formed.…”

Section: -(Trimethylsilyl)-3-bromothiophene (8)mentioning

confidence: 99%

Characterisation of a dipolar chromophore with third-harmonic generation applications in the near-IR

et al. 2012

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E-2-Tricyanovinyl-3-n-hexyl-5-[4-{bis(4-n-butylphenyl)amino}-2-methoxystyryl]-thiophene, 1, has previously been used to demonstrate applications relying on frequency tripling of 1.55 mm light. Here we report the synthesis and chemical characterisation of 1, along with quantum-chemical calculations and additional experimental investigations of its third-order nonlinear properties that give more insight into its frequency tripling properties. Although 1 can be processed into amorphous films, crystals can also be grown by slow evaporation of solutions; the crystal structure determined by X-ray diffraction shows evidence of significant contributions from zwitterionic resonance forms to the ground-state structure, and reveals centrosymmetric packing exhibiting p-p and C-H/N^C interactions. Both solutions and films of 1 exhibit near-infrared two-photon absorption into the low-lying one-photon-allowed state with a peak two-photon cross-section of ca. 290 GM (measured using the white-light continuum method with a pump wavelength of 1800 nm) at a transition energy equivalent to degenerate two-photon absorption at ca. 1360 nm; two related chromophores are also found to show comparable near-IR two-photon crosssections. Closed-aperture Z-scan measurements and quantum-chemical calculations indicate that the nonlinear refractive index and third-harmonic generation properties of 1 are strongly dependent on frequency in the telecommunications range, due the aforementioned two-photon resonance.

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Section: -(Trimethylsilyl)-3-bromothiophene (8)mentioning

confidence: 99%

Characterisation of a dipolar chromophore with third-harmonic generation applications in the near-IR

et al. 2012

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“…11,12 Polythiophene and a number of its derivatives have been synthesized and studied extensively. However, only a few articles have reported poly(3-halide thiophene)s, [13][14][15][16][17] and among them, only one short communication is concerned with the direct oxidation of 3-chlorothiophene (CT). 14 The oxidation of CT requires a very high potential in a neutral solvent (2.18 V vs saturated calomel electrode), and the polymer obtained from this medium is powdery and has low conductivity (Ͻ10 Ϫ2 S cm Ϫ1 ).…”

Section: Introductionmentioning

confidence: 99%

Poly(3‐chlorothiophene) films prepared by the direct electrochemical oxidation of 3‐chlorothiophene in mixed electrolytes of boron trifluoride diethyl etherate and sulfuric acid

Shi

Chen

et al. 2002

J of Applied Polymer Sci

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3-Chlorothiophene (CT) was electrochemically polymerized in mixed electrolytes of a boron trifluoride diethyl etherate solution containing 0 -20% (by volume) sulfuric acid. The oxidation potentials of the monomer in these media were measured to be only 1.06 -1.31 V (vs Ag/AgCl). These values were much lower than that of CT in acetonitrile and 0.1 mol/L (Bu) 4 NBF 4 (1.92 V vs Ag/AgCl). Poly(3-chlorothiophene) (PCT) films with conductivities of 0.1-2 S cm Ϫ1 were obtained. The structure, morphology, and electrochemical behavior of the PCT films also were investigated.

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“…20 In route A, 3-bromothiophene 3 is treated with LDA, followed by addition of trimethylchlorosilane (TMSCl), to give TMS-protected product 4. 21 Treatment with LDA, followed by addition of N-methoxy-N-methyloctanamide provides ketone 5. 22,23 Subsequent reduction and deprotection of the TMS group gives thiophene 7 in isolated 45% yield for four steps.…”

mentioning

confidence: 99%

Synthesis of Functionalized Carbon-Sulfur [5]Helicene: Pd-Catalyzed Negishi Cross-Coupling Between the β-Positions of Thiophenes

Miyasaka¹,

Rajca²

2004

Synlett

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Octyl-and bromo-substituted carbon-sulfur [5]helicene was prepared in several steps starting from either thiophene or 3-bromothiophene. Pd-catalyzed Negishi cross-coupling between the b-positions of thiophenes was one of the key steps in the synthesis.Helicenes, molecules with annelated and helical p-conjugated systems, have been known for about 50 years. 1-3 In the past few years, there has been a resurgence of interest in synthesis of helicenes. 4-10 Because of the strong chiral, especially chirooptical, properties, helicenes are attractive building blocks for chiral materials. 11 Our own interest is the development of amorphous thin films with extraordinary high optical rotatory powers for optical waveguides and magneto-conductive materials (e.g., chiral metals). 12,13 Carbon-sulfur helicenes may be viewed as novel annelated oligothiophenes and as fragments of the intriguing (C 2 S) n carbon-sulfur helix ( Figure 1). 14-17 C 2 -symmetric [7]helicene 1 is the only helicene of this class known to date. 18 [7]Helicene 1 can be obtained in one enantiomeric form. 19 Short helicenes, which are adequately functionalized for metal-catalyzed cross-couplings and possess relatively low barriers for racemization, are desirable for efficient syntheses of extended helicenes. Well-soluble alkyl-substituted helicenes, compatible with a wide range of redox potentials, are among the targets. We now report the synthesis of C 1 -symmetric carbon-sulfur [5]helicene 2 ( Figure 1).The previously reported iterative synthesis of C 2 -symmetric 1 was based upon Cu II -mediated CC-bond forming homocouplings between the b-positions and CS-bond forming annelations at the a-positions of thiophenes. 18 Although the b-positions of thiophenes, especially when sterically hindered, may be considered as 'difficult' for CC-bond forming cross-couplings, the development of suitable conditions may allow for an efficient synthesis of less symmetric helicenes, such as 2.4-Bromo-2-octylthiophene 7 is prepared according to two routes (Scheme 1). 20 In route A, 3-bromothiophene 3 is treated with LDA, followed by addition of trimethylchlorosilane (TMSCl), to give TMS-protected product 4. 21 Treatment with LDA, followed by addition of N-methoxy-N-methyloctanamide provides ketone 5. 22,23 Subsequent reduction and deprotection of the TMS group gives thiophene 7 in isolated 45% yield for four steps. 24 Route B offers a shorter, three-step synthesis of 7, starting from inexpensive thiophene 8. Monoalkylation of metallated thiophene provides 2-octylthiophene 9, which is brominated with NBS to yield 10. [25][26][27] Lithiation with LDA in THF, followed by MeOH-quench results in rearranged product 7 in isolated 36% yield for three steps. 28 The reaction conditions for the Negishi coupling between 7 (1.0 equiv) and 12 (0.84 equiv) are optimized as follows Figure 1 Scheme 1 Synthesis of 4-bromo-2-octylthiophene 7. S Br S Br TMS X S Br X C 8 H 17

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Selective Electrochemical Mono- and Polysilylation of Halothiophenes

Cited by 20 publications

References 24 publications

Characterisation of a dipolar chromophore with third-harmonic generation applications in the near-IR

Characterisation of a dipolar chromophore with third-harmonic generation applications in the near-IR

Poly(3‐chlorothiophene) films prepared by the direct electrochemical oxidation of 3‐chlorothiophene in mixed electrolytes of boron trifluoride diethyl etherate and sulfuric acid

Synthesis of Functionalized Carbon-Sulfur [5]Helicene: Pd-Catalyzed Negishi Cross-Coupling Between the β-Positions of Thiophenes

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