Palladium-Catalyzed Cross-Coupling Reaction of Silicone with Aryl Chlorides

Abstract

The palladium-catalyzed cross-coupling reaction of silicone, poly(diorganosiloxane), with aryl chlorides in the presence of K₂CO₃/H₂O as an activator proceeds to afford the biaryl derivatives in moderate to excellent yields. A wide range of aryl chlorides bearin­g an electron-donating or electron-withdrawing substituent on the aromatic ring are tolerated. The amount of K₂CO₃ relative to silicone significantly influences the reaction. Treatment of silicone with K₂CO₃/H₂O at r.t. for 1 hour prior to the addition of the palladium catalyst and an aryl chloride is necessary.

palladium - cross coupling - silicone - aq potassium carbona­te - aryl chlorides

References

<A NAME="RU12403ST-1A">1a</A> Mori A. Suguro M. Synlett  2001,  845 

<A NAME="RU12403ST-1B">1b</A>

Average mol. wt of 1 employed is ca. 2500-2700.

<A NAME="RU12403ST-2">2</A> Koike T. Du X. Mori A. Osakada K. Synlett  2002,  301 

<A NAME="RU12403ST-3A">3a</A> Hirabayashi K. Kawashima J. Nishihara Y. Mori A. Hiyama T. Org. Lett.  1999,  1:  299 

<A NAME="RU12403ST-3B">3b</A> Hirabayashi K. Kondo T. Toriyama F. Nishihara Y. Mori A. Bull. Chem. Soc. Jpn.  2000,  73:  985 

<A NAME="RU12403ST-3C">3c</A> Nishihara Y. Ikegashira K. Hirabayashi K. Ando J. Mori A. Hiyama T. J. Org. Chem.  2000,  65:  1780 

<A NAME="RU12403ST-3D">3d</A> Fujii T. Koike T. Mori A. Osakada K. Synlett  2002,  295 

<A NAME="RU12403ST-3E">3e</A> Fujii T. Koike T. Mori A. Osakada K. Synlett  2002,  298 

<A NAME="RU12403ST-3F">3f</A> Mowery ME. DeShong P. Org. Lett.  1999,  1:  2137 

<A NAME="RU12403ST-3G">3g</A> Mowery ME. DeShong P. J. Org. Chem.  1999,  64:  1684 

<A NAME="RU12403ST-3H">3h</A> Denmark SE. Wehrli D. Org. Lett.  2003,  5:  1357 ; and references cited therein

<A NAME="RU12403ST-3I">3i</A> Mori A. Danda Y. Fujii T. Hirabayashi K. Osakada K. J. Am. Chem. Soc.  2001,  123:  10774 

<A NAME="RU12403ST-3J">3j</A> For a review: Organosilicon Compounds in Cross-Coupling Reactions, see: Hiyama T. In Metal-Catalyzed Cross-Coupling Reactions   Diederich F. Stang PJ. Wiley-VCH; Weinheim: 1998.  p.421 

Recent palladium-catalyzed cross-coupling reaction of aryl chlorides using organometallic reagents, see:

<A NAME="RU12403ST-4A">4a</A> Old DW. Wolfe JP. Buchwald SL. J. Am. Chem. Soc.  1998,  120:  9722 

<A NAME="RU12403ST-4B">4b</A> Littke AF. Schwarz L. Fu GC. Angew. Chem. Int. Ed.  1998,  37:  3387 

<A NAME="RU12403ST-4C">4c</A> Zhang C. Huang J. Trudell ML. Nolan SP. J. Org. Chem.  1999,  64:  3804 

<A NAME="RU12403ST-4D">4d</A> Littke AF. Fu GC. Angew. Chem. Int. Ed.  1999,  38:  2411 

<A NAME="RU12403ST-4E">4e</A> Wolfe JP. Buchwald SL. Angew. Chem. Int. Ed.  1999,  38:  2413 

<A NAME="RU12403ST-4F">4f</A> Hagiwara E. Gouda K. Hatanaka Y. Hiyama T. Tetrahedron Lett.  1997,  38:  439 

<A NAME="RU12403ST-4G">4g</A> Gouda K. Hagiwara E. Hatanaka Y. Hiyama T. J. Org. Chem.  1996,  61:  7232 

<A NAME="RU12403ST-5">5</A> PdCl₂(PCy₃)₂ was prepared according to the literature procedure, see : Grushin VV. Alper H. Organometallics  1993,  12:  1890 

<A NAME="RU12403ST-6">6</A> Available from Aldrich Chemicals Co. as TBAF·xH₂O

<A NAME="RU12403ST-7A">7a</A> Grushin VV. Alper H. Chem. Rev.  1994,  94:  1047 

<A NAME="RU12403ST-7B">7b</A> Littke AF. Fu GC. Angew. Chem. Int. Ed.  2002,  41:  4176 

<A NAME="RU12403ST-8">8</A>

Typical Experimental Procedure for the Cross-Coupling Reaction: To a toluene (3 mL) solution of [Ph(Me)SiO]_n (1, 204 mg, 1.5 mmol) was added K₂CO₃ (414 mg, 3.0 mmol) in water (0.5 mL). After stirring at r.t. for 1 h, 1-chloro-4-methoxybenzene (2a, 43 mg, 0.3 mmol) and PdCl₂(PCy₃)₂ (11 mg, 0.015 mmol) were added and then the resulting yellow mixture was stirred at 120 °C for 39 h. After cooling the mixture to r.t., the organic layer was separated and aqueous layer was extracted with Et₂O (2 × 10 mL). The combined organic layer was washed with 1 M HCl (10 mL), sat. aq NaHCO₃ (10 mL), and brine (10 mL) and then dried over anhyd MgSO₄. Removal of the solvent left a crude oil, which was purified by chromatography on silica gel (reverse phase, MeOH-H₂O = 3:1) to yield 52.5 mg of 4-methoxy-biphenyl (95%).

<A NAME="RU12403ST-9">9</A> The related mechanism has also been proposed in the Stille coupling reaction of chloroarenes: Bedford RB. Cazin CSJ. Hazelwood SL. Chem. Commun.  2002,  2608