Lithium (Z)-Bis(2-ethoxyvinyl)cuprate1

[64823-09-2]  · C8H14CuLiO2  · Lithium (Z)-Bis(2-ethoxyvinyl)cuprate  · (MW 212.71)

(a lower order cuprate reagent, prepared in situ, which undergoes conjugate addition reactions and substitution reactions2)

Solubility: sol THF.

Preparative Methods: 1-Ethoxy-2-tributylstannylethylene is prepared by the hydrostannation of Ethoxyacetylene, which is then reacted with 1.1 equiv of n-Butyllithium in THF at -78 °C for 1 h to afford (Z)-2-Ethoxyvinyllithium. To this solution is added 0.5 equiv purified Copper(I) Iodide and 2.0 equiv Dimethyl Sulfide in THF. The mixture is stirred for 1 h, affording lithium bis(2-ethoxyvinyl)cuprate, a red-brown solution.2

Handling, Storage, and Precautions: air- and moisture-sensitive reagent prepared and used in situ. Use in a fume hood.

1,4-Addition Reactions with a,b-Unsaturated Carbonyl Compounds.

Lithium bis(2-ethoxyvinyl)cuprate undergoes 1,4-addition to a,b-alkenyl and a,b-alkynyl ketones by conjugate transfer of the 2-ethoxyvinyl ligand (eqs 1 and 2).2

Substitution Reactions.

Lithium bis(2-ethoxyvinyl)cuprate reacts with alkyl halides in substitution reactions (eq 3).2

In reactions of enantiomerically pure alkyl bromide, substitution occurs with inversion of configuration at carbon. If the halogen is iodine, the reaction affords racemic product.3

Related Reagents.

1-Ethoxyvinyllithium; Lithium Bis(1-ethoxyvinyl)cuprate; Lithium Bis(1-methoxyvinyl)cuprate; Lithium Divinylcuprate.

1. Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135.
2. Wollenberg, R. H.; Albizati, K. F.; Peries, R. JACS 1977, 99, 7365.
3. Lipshutz, B. H.; Wilhelm, R. S. JACS 1982, 104, 4696.

Elisabeth R. Johnston & Christopher W. Alexander

Emory University, Atlanta, GA, USA

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