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Synlett 2010(19): 2936-2940  
DOI: 10.1055/s-0030-1259023
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Csp³-Csp² Palladium-Catalyzed Cross-Coupling Reaction of Trialkylbismuth Reagents with Aryl, Heteroaryl, and Vinyl Halides and Triflates

Alexandre Gagnon*, Vincent Albert, Martin Duplessis*
Boehringer Ingelheim (Canada) Ltd., Research and Development, 2100 Cunard Street, Laval, Québec, H7S 2G5, Canada
Fax: +1(450)6824189; e-Mail: martin.duplessis@boehringer-ingelheim.com;
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Publication History

Received 13 August 2010
Publication Date:
03 November 2010 (online)

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Abstract

The palladium-catalyzed cross-coupling reaction of trialkylbismuth reagents with aryl and heteroaryl halides and triflates is reported. Moderate to good yields were obtained for the transfer of primary alkyl groups. The reaction tolerates numerous functional groups on the electrophilic and nucleophilic partners. The cross-coupling of α-bromostyrene with tris(1,3-dioxan-2-ylethyl)bismuth is also reported.

Key words

cross-coupling - organometallic reagents - palladium - halides - catalysis

1

Current address: Constellation Pharmaceuticals, Cambridge, MA, USA; alex.gagnon@constellationpharma.com.

16

General Procedure for the Preparation of 4, 6a-o, and 8 In a round-bottom flask equiped with a condenser and sparged with argon, BiCl3 (173 mg, 0.55 mmol) was suspended in anhydrous THF (3 mL) and cooled to 0 ˚C. The organomagnesium reagent (1.705 mmol, THF or Et2O solution) was slowly added dropwise, and the solution was stirred at 0 ˚C for 30 min, warmed to r.t., and then heated at 65 ˚C for an additional 30 min. The reaction mixture was cooled to r.t. and diluted with DMF (1 mL). A DMF solution of the aryl or heteroaryl halide or pseudo halide (0.500 mmol in 4 mL) was then added, followed by K2CO3 or Cs2CO3 (1.00 mmol) and Pd(PPh3)4 (28 mg, 0.025 mmol). The solution was degassed by bubbling argon during 15 min, and then stirred at 110 ˚C for 18 h. The reaction mixture was cooled to r.t., diluted with sat. aq NaHCO3 (10 mL) and extracted with EtOAc (2 × 10 mL). The combined organic phases were washed with brine (3 × 10 mL), dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (1% to 15% EtOAc-hexanes or Et2O-hexanes) to afford the desired products 4, 6a-o, and 8.
Spectral Data for 6n R f = 0.41 (20% EtOAc-hexanes). ¹H NMR (400 MHz, CDCl3): δ = 8.81 (d, J = 1.8 Hz, 1 H), 8.08 (d, J = 8.4 Hz, 1 H), 7.94 (s, 1 H), 7.76 (d, J = 8.1 Hz, 1 H), 7.66 (t, J = 8.2 Hz, 1 H), 7.53 (t, J = 7.0 Hz, 1 H), 4.56 (t, J = 5.1 Hz, 1 H), 4.12 (dd, J = 10.0, 5.0 Hz, 2 H), 3.76 (dt, J = 12.5, 2.4 Hz, 2 H), 2.93 (t, J = 7.8 Hz, 2 H), 2.13-2.04 (m, 1 H), 2.02-1.99 (m, 2 H), 1.35 (d, J = 13 Hz, 1 H). ¹³C NMR (100 MHz, CDCl3): δ = 152.5, 147.2, 134.8, 134.7, 129.6, 129.0, 128.6, 127.8, 127.0, 101.4, 67.3, 36.6, 27.7, 26.2. IR (neat): 2959, 2850, 1494, 1378, 1240, 1138, 1082, 1043, 1002 cm-¹. HRMS (EI): m/z calcd for C15H17NO2 [M]: 243.1259; found: 244.1328 [M + H].