[48003-18-5] · C4H11CuSi · Trimethylsilylmethylcopper · (MW 150.79)
(organocopper reagent which undergoes smooth SN2´ and addition reactions)
Physical Data: exists in tetrameric form;2 tetrakis[trimethylsilylmethylcopper(I)] consists of discrete, centrosymmetric, tetrameric units containing a square plane of copper atoms (Cu-Cu 2.42 Å), with the methylene carbons lying in the same plane and bridging the edges.
Solubility: sol THF.
Preparative Method: prepared under an inert atmosphere of argon by addition of Trimethylsilylmethylmagnesium Chloride (prepared starting from (trimethylsilyl)methyl chloride) to a solution of LiCuBr2 in THF at -65 °C and then stirring for 15 min.
Handling, Storage, and Precautions: air- and moisture-sensitive reagent prepared in situ. Use in a fume hood.
Trimethylsilylmethylcopper is a suitable reagent to convert a-acetylenic oxiranes, a-allenic oxiranes and a-allenic methanesulfinates, as well as disulfonates, into the corresponding 1,3-substitution products in good yield (80-90%) (eq 1). These reactions proceed with good regiospecificity. The advantage of trimethylsilylmethylcopper over R2CuM is that RCu generally gives cleaner reaction products, especially when propargylic compounds are the substrates. Trimethylsilylmethylcopper is more effective than R2CuM in reactions with sulfinates because R2CuM attacks the sulfinate functionality itself.3 This conversion consists of two successive 1,3-substitution reactions (eq 2).
Trimethylsilylmethylcopper adds smoothly to a variety of activated carbon-carbon triple bonds (eq 3). The adducts are formed predominantly in a stereoselective or even stereospecific cis-addition in good yields (70-95%).
Emory University, Atlanta, GA, USA