Typical Experimental Details of Copper Chemistry

An example of a typical reduction for copper is as follows Into a 50-ml twonecked flask is placed 0.3522 g (9.006 mmol) of potassium, 1.7075 g (8.996 mmol) of cuprous iodide, 0.1204g (0.9393 mmol) of naphthalene, and 10.0ml ofDME. This is stirred vigorously until the reduction is complete ( 8h). The activated copper appears as a gray-black slurry which setdes out of the clear, colorless solution. The cuprous iodide used was purchased from Cerac, Inc., Milwaukee, Wisconsin, and was 99% pure. 

The reduction is complete when the solution is clear and colorless. There should be no hint of the green naphthalenide radical anion visible in the supernatant solution. This slurry does not flash or show other indications of alkali metal when syringed onto the surface of water. If the reduction is incomplete or after a partial reaction of the activated copper, the aforementioned aqueous quench will cause the precipitation of white cuprous iodide (decomposition of the soluble copper complexes occurs). 

Reaction of K-Generated Copper with Pentafluorophenyl Iodide 

The active copper as generated in the preceding text was allowed to react with pentafluorophenyl iodide (molar ratios of 3.3 1) at room temperature in DME for 30 min. The supernatant solution was then anaerobically transferred to another flask, where the solvent and excess aryl iodide were removed under vacuum to leave a tan solid containing pentafluorophenyl copper. This tan solid was difficult to purify however, its chemistry matches that published for pure pentafluorophenyl copper. Yields were in the range of 70-80%. 

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Typical Experimental Details of Copper Chemistry 233 Table 5.14 1,4-Conjugate additions with copper anion-based allyl organocopper reagents. 

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