Diethylzinc three-component reactions

Scheme 4.21 Three-component reaction of 1,4-diphenylbuta-l,3-diene, aldehydes, and diethylzinc.

Scheme 4.31 Three-component reaction of alkynes, imines, and diethylzinc.

Dialkylzincs display reactivity completely different from alkylzinc halides. For example, diethylzinc even undergoes the three-component connection reaction smoothly at 0 °C irrespective of the absence or presence of HMPA (Scheme... 

In 2007, Shibasaki et al. reported a three-component domino reaction induced by cooperative catalysis between copper and zinc. This novel domino reaction occurred between acetophenone, diethylzinc and an allenic ester, providing the corresponding chiral lactone in high yield and excellent enantioselectivity of 96% ee, as shown in Scheme 3.1. The process began with the addition of diethylzinc to the allenic ester, which was followed by an aldolisation with acetophenone, and a lactonisation reaction gave the final product. Initially, the Cu(ii) was reduced to Cu(i) in the presence of... 

The optimal procedure calls for a three-flask protocol which segregates the individual reactive components. Pre-formation of the zinc alkoxide, zinc sulfonamide complex and the cyclopropanation reagent, Zn(CH2l)2. by combination of diethylzinc with the allyhc alcohol, his-sulfonamide and diiodomethane, respectively, is essential for high selectivity and reproducibility. While the individual reaction components are soluble in halogenated sol-... 

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