Chloromagnesium Dimethylcuprate1


[67234-12-2]  · C2H6ClCuMg  · Chloromagnesium Dimethylcuprate  · (MW 153.39) (Me2Cu-)

[47942-29-0]  · C2H6Cu  · Chloromagnesium Dimethylcuprate  · (MW 93.63) (MgCl+)

[32195-53-2]  · ClMg  · Chloromagnesium Dimethylcuprate  · (MW 59.76)

(methyl transfer reagent in conjugate additions)

Alternate Name: dimethylcoppermagnesium chloride.

Physical Data: prepared in situ.

Preparative Methods: methylmagnesium chloride (1 equiv) in THF is added dropwise to a rapidly stirred slurry of Copper(I) Iodide iodide (0.5 equiv) in anhydrous THF at -78 °C, and the resultant mixture is stirred at -78 °C for 15 min.2 In a similar way, the reagent is generated using 0.5 equiv LiCuBr23 (15 min, -60 °C) or Copper(I) Bromide.4

Handling, Storage, and Precautions: the reagent must be generated and used immediately in the absence of moisture and oxygen. Handle in a fume hood.

Chloromagnesium dimethylcuprate seems to be a forgotten brother of its bromo analog. A few studies show some superior qualities in conjugate additions. In reaction with a,b-unsaturated aldehydes the reagent gives 1,4-adducts almost exclusively (eq 1);4 it reacts readily at low temperature in a stereoselective manner with 2-alkyne nitriles without the need for a large excess of the reagent (eq 2).5

Related Reagents.

Methylmagnesium Iodide-Copper(I) Chloride; Vinylmagnesium Bromide-Copper(I) Iodide; Vinylmagnesium Chloride-Copper(I) Chloride.

1. Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135.
2. Freye, L. L.; Sullivan, E. L.; Cusack, K. P.; Funaro, J. M. JOC 1992, 57, 697.
3. Westmijze, H.; Nap, I.; Meijer, J.; Kleijn, H.; Vermeer, P. RTC 1983, 102, 154.
4. Chuit, C.; Foulon, J. P.; Normant, J. F. T 1981, 37, 1385.
5. Westmijze, H.; Kleijn, H.; Vermeer, P. S 1978, 6, 454.

Lucjan Strekowski & Koen Van Aken

Georgia State University, Atlanta, GA, USA

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