Synlett 2020; 31(13): 1328-1332
DOI: 10.1055/s-0039-1690877
letter
© Georg Thieme Verlag Stuttgart · New York

Palladium-Catalyzed Silylation of Aryl Chlorides with Bulky Dialkoxydisilanes

Keitaro Fukui
,
,
Jun Shimokawa
,
This work was supported by the Japan Society for the Promotion of Science (JSPS KAKENHI Grant Numbers JP16H04109, JP18H04254, JP18H04409, JP19H00895, JP18J22838), and partly by Core Research for Evolutional Science and Technology (JST CREST Grant Number JPMJCR19R4), Japan. J.S. thanks the support from the Kyoto University Research Development Program (ISHIZUE 2019). H.Y. thanks The Asahi Glass Foundation for financial support.
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Publikationsverlauf

Received: 02. März 2020

Accepted after revision: 18. März 2020

Publikationsdatum:
02. April 2020 (online)


Abstract

Arylsilanes bearing a bulky alkoxy group on the silicon were synthesized from aryl chlorides and dialkoxydisilanes under reaction conditions utilizing SingaCycle-A3 as a palladium precatalyst and lithium benzoate in wet DMA. This report proposes the first direct and catalytic method for introducing tert-butoxy- or 1-adamantyloxysilyl groups onto various aryl moieties through the silylation reaction.

Supporting Information

 
  • References and Notes

  • 4 Hiyama–Denmark-type coupling reaction of an arylsilane bearing tBuOMe2Si group with 4-iodoanisole under unoptimized conditions gave the cross-coupling product in ca. 40% yield.
  • 8 Kantchev EA. B, Ying JY. Organometallics 2009; 28: 289
  • 9 Ethyl 4-(tert-butoxydimethylsilyl)benzoate (6a) – Typical Procedure An oven-dried 30 mL Schlenk tube was charged with LiOBz (96.0 mg, 0.75 mmol), SingaCycle-A3 (10.0 mg, 0.015 mmol), and DMA (1.5 mL) under nitrogen atmosphere. Ethyl 4-chlorobenzoate (4a, 92.3 mg, 0.50 mmol), 1,2-di-tert-butoxy-1,1,2,2-tetramethydisilane (5, 235 μL, 0.75 mmol), and H2O stock solution (0.17 M in DMA, 0.15 mL, 25 μmol) were sequentially added to the mixture. DMA (1.35 mL) was added to wash the inner side of the tube. The reaction mixture was stirred at 100 °C for 12 h and quenched with sat. aq NaHCO3 (10 mL). The mixture was poured into a separatory funnel with EtOAc (20 mL) and partitioned. The organic phase was collected and washed with sat. aq NaHCO3 (10 mL), sat. aq NH4Cl (10 mL), brine (10 mL), dried over anhydrous Na2SO4 (ca. 5 g), filtered, and concentrated in vacuo. The residue was purified by column chromatography on silica gel with an eluent (hexane and hexane/EtOAc = 100:1) to afford 6a (105.6 mg, 0.38 mmol, 75%) as colorless oil. 1H NMR (CDCl3, 600 MHz): δ = 8.01 (d, J = 8.2 Hz, 2 H), 7.67 (d, J = 8.2 Hz, 2 H), 4.38 (q, J = 6.9 Hz, 2 H), 1.39 (t, J = 6.9 Hz, 3 H), 1.25 (s, 9 H), 0.39 (s, 6 H). 13C NMR (CDCl3, 151 MHz): δ = 167.0, 146.8, 133.4, 131.0, 128.6, 73.2, 61.0, 32.2, 14.5, 1.5. HRMS: m/z calcd for C15H25O3Si [M + H]+: 281.1567; found: 281.1569.
  • 10 O’Brien CJ, Kantchev EA. B, Valente C, Hadai N, Chass GA, Lough A, Hopkinson AC, Organ MG. Chem. Eur. J. 2006; 12: 4743
  • 11 1-[4-(tert-Butoxydimethylsilyl)phenyl]ethan-1-one (6b) Reaction time was 12 h. Column chromatography with an eluent (hexane to hexane/EtOAc = 30:1) afforded 6b as colorless oil (85.9 mg, 0.34 mmol, 69%) from 4b (77.3 mg, 0.50 mmol). 1H NMR (CDCl3, 600 MHz): δ = 7.92 (d, J = 8.2 Hz, 2 H), 7.70 (d, J = 8.2 Hz, 2 H), 2.61 (s, 3 H), 1.26 (s, 9 H), 0.39 (s, 6 H). 13C NMR (CDCl3, 151 MHz): δ = 198.6, 147.3, 137.5, 133.7, 127.3, 73.2, 32.2, 26.8, 1.5. HRMS: m/z calcd for C14H23O2Si [M + H]+: 251.1462; found: 251.1461.
  • 12 4-(tert-Butoxydimethylsilyl)benzonitrile (6c) Reaction time was 12 h. Column chromatography with an eluent (hexane to hexane/EtOAc = 100:1) afforded 6c as colorless oil (89.6 mg, 0.38 mmol, 77%) from 4c (68.8 mg, 0.50 mmol). 1H NMR (CDCl3, 600 MHz): δ = 7.68 (d, J = 8.2 Hz, 2 H), 7.62 (d, J = 8.2 Hz, 2 H), 1.26 (s, 9 H), 0.39 (s, 6 H). 13C NMR (CDCl3, 151 MHz): δ = 147.4, 133.9, 131.1, 119.3, 112.7, 73.4, 32.2, 1.5. HRMS: m/z calcd for C13H20NOSi [M + H]+: 234.1309; found: 134.1304.
  • 13 X-ray crystallographic analysis revealed the bulky adamantyloxy groups are antiperiplanar across the Si–Si bond. See the Supporting Information for details.
  • 14 Maji A, Guin S, Feng S, Dahiya A, Singh V, Liu P, Maiti D. Angew. Chem. Int. Ed. 2017; 56: 14903
  • 15 We could not deny the possibility that disilane 5 reacts with Pd(II) benzoate through a concerted six-membered transition state to give silyl benzoate 15 and an Ar–Pd(II)–SiMe2(OtBu) species, which would then generate arylsilane 6 via reductive elimination.