[Stereoseletivity of 1,4-addition of dialkylphenylsilyl cuprates to 2-aryl-2-cycloenones and synthesis of 2-substituted-3-silylcycloalkanones]

The stereoselectivity of 1,4-addition of dialkylphenylsilyl cuprates to 2-cycloenones was investigated and meantime a series of new 2-substituted-3-silylcycloalkanones were synthesized. It was found that the stereoselectivity of the 1,4-addition of dialkylphenylsilyl cuprates to 2-aryl-2-cycloenones depended on the nature of aryl group and ring size by quenching the reactions with saturated NH4Cl solution at 0 degrees C. However, it was first found that the addition gave very high trans selectivity independent of the aryl group, ring size and substituents on the silicon atom by quenching the reactions with methanol at room temperature. It was also observed that arylmethyl bromides reacted with enolates resulting from 1,4-addition of dimethylphenylsilyl cuprate to 2-cycloenones giving exclusively trans isomers. All products were characterized by IR, H-1 NMR, C-13 NMR, MS and HRMS spectra