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DOI: 10.1055/s-2003-43358
Preparation and Reactions of Polyfunctional Magnesium Arylcuprates Obtained by an Iodine-Copper Exchange
Publication History
Publication Date:
26 November 2003 (online)
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Abstract
The preparation of polyfunctional magnesium cuprates of type 1 can be achieved via an iodine-copper exchange reaction using the cyclic magnesium cuprate 3. A range of functional groups like an ester, halide (F, Br), nitrile or even a ketone can be tolerated. The new cuprates can be acylated and allylated in good yields leading to a range of polyfunctional products.
Key words
functionalized organometallics - cuprates - acylation - magnesium - iodine-copper exchange
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References
Typical Procedure: A dry and argon filled 25 mL flask, equipped with a magnetic stirrer and a septum, was charged with a solution of 1,5-bis(bromomagnesium)pentane (0.46 M/THF, 4.4 mL, 2.0 mmol) in THF (8 mL). The solution of CuCN·2LiCl in THF (1.0 M/THF, 2.0 mL, 2.0 mmol) was added dropwise at -78 °C. The resulting mixture was stirred for 30 min and ethyl 4-iodobenzoate 4a (552 mg, 2.0 mmol) was added at -78 °C. The resulting mixture was warmed to r.t. for 1 h and then benzoyl chloride (421 mg, 3.0 mmol) was added. After 30 min, the solution was quenched with sat. aq NH4Cl solution and poured into H2O (20 mL). The organic layer was separated and the aqueous phase was extracted with Et2O (3 × 50 mL). The organic fractions were washed with brine (30 mL), dried over MgSO4 and concentrated in vacuo. Purification by chromatography (SiO2, n-pentane/Et2O = 50:1) yielded 478 mg (94% yield) of 8b as a colorless oil. IR (film): 3402 (m, br), 2982 (m), 1720(vs), 1661 (vs), 1597 (m), 1579 (w), 1448 (m), 1405 (s), 1356 (s), 1369 (s), 1317 (s), 1275(vs), 1105(vs), 1020 (m), 939 (m), 927 (m), 851 (w), 769 (w), 715 (s), 698 (m), 657 (m)cm-1. 1H NMR (300 MHz, CDCl3): δ = 8.07 (dd, J = 8.4 and 1.8 Hz, 2 H), 7.73 (m, 4 H), 7.53 (m, 1 H), 7.40 (t, J = 8.0 Hz, 2 H), 4.34 (q, J = 7.2 Hz, 2 H), 1.33 (t, J = 7.1 Hz, 3 H). 13C NMR (75 MHz, CDCl3): δ = 195.0, 164.8, 140.2, 136.0, 132.6, 131.9, 129.1, 128.7, 128.4, 127.4, 126.2, 60.4, 13.3. MS (EI, 70 eV): m/z (%) = 254 (48) [M+], 226 (14), 209 (45), 181 (18), 177 (57), 152 (10), 149 (14), 130 (20), 118 (17), 104 (100). HRMS (EI): calcd for C16H14O3 [M+]: 527.7580. Found: 527.7579.