n-Butylmagnesium Bromide-Methylcopper(I)1

n-BuMgBr-MeCu

[59532-66-0]  · C5H12BrCuMg  · n-Butylmagnesium Bromide-Methylcopper(I)  · (MW 239.90) (n-BuMeCu-)

[70196-77-9]  · C5H12Cu  · n-Butylmagnesium Bromide-Methylcopper(I)  · (MW 135.70) (MgBr+)

[43245-19-8]  · BrMg  · n-Butylmagnesium Bromide-Methylcopper(I)  · (MW 104.21)

(serves as a butyl transfer reagent in substitution reactions)

Alternate Names: butylmethylcopper(I)magnesium bromide; bromomagnesium butylmethylcuprate.

Solubility: sol ether, THF.

Preparative Methods: a suspension of CuI (1.5 mmol) in THF (3 mL) is stirred at -78 °C and treated with a solution of salt-free MeLi (1.5 mmol) in ether. The resultant yellow precipitate of MeCu dissolves when a THF solution of n-BuMgBr (1.5 mmol) is added and a purple solution is formed.2,3 In a similar fashion, the reagent is prepared from CuI, salt-free n-BuLi, and MeMgI.3

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

Butylmagnesium bromide-methylcopper is a mixed lower order magnesium cuprate. It shows increased thermal stability in comparison to Lithium Di-n-butylcuprate. The reagent selectively transfers the n-butyl group in reactions with acid chlorides (eq 1)2 or 5-acetoxy-1,3-alkadienes (eq 2).3

Related Reagents.

Lithium Di-n-butylcuprate; Vinylmagnesium Bromide-Methylcopper.


1. Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135.
2. Bergbreiter, D. E.; Killough, J. M. JOC 1976, 41, 2750.
3. Nakanishi, N.; Matsubara, S.; Utimito, K.; Kozima, S.; Yamaguchi, R. JOC 1991, 56, 3278.

Lucjan Strekowski & Koen Van Aken

Georgia State University, Atlanta, GA, USA



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