Conjugate additions of a simple monosilylcopper reagent with use of the CuI.DMS complex: stereoselectivities and a dramatic impact by DMS

Jesse Dambacher; Mikael Bergdahl

doi:10.1021/jo048269e

Conjugate additions of a simple monosilylcopper reagent with use of the CuI.DMS complex: stereoselectivities and a dramatic impact by DMS

J Org Chem. 2005 Jan 21;70(2):580-9. doi: 10.1021/jo048269e.

Authors

Jesse Dambacher¹, Mikael Bergdahl

Affiliation

¹ Department of Chemistry and Biochemistry, San Diego State University, San Diego, California, 92182-1030, USA.

PMID: 15651805
DOI: 10.1021/jo048269e

Abstract

Conjugate additions utilizing the simple monosilylcuprate reagent Li[PhMe2SiCuI] to alpha,beta-unsaturated carbonyl compounds are described. The presence of dimethyl sulfide (DMS), either as a component originating from the (CuI)4(DMS)3 complex or as a solvent added, has an amazing influence on both chemical yield and the level of diastereomeric ratio (dr) of the products. Gilman-type silylcyanocuprates {Li(Ph2MeSi)2Cu/LiCN} have previously been used to guarantee good results in conjugate addition reactions. External additives such as HMPA, tributylphosphine, or dialkylzinc are not necessary in conjunction with the simple Li[PhMe2SiCuI] reagent. It is demonstrated that the monosilylcuprate reagent with DMS as the solvent is very useful with sterically hindered (beta,beta-disubstituted) enones, and provides very high yields of the beta-silylated 1,4-addition products. Since there is no oligomerization problem associated with the simple monosilylcuprate reagent, this reagent should be considered as a very useful 1,4-silyl donor to enals, enones, and enoates in conjugate addition reactions.