STUDY ON THE REACTIVITY OF ALLYLTRIMETHYL SILANE WITH ALPHA-CYCLOPROPANE KETONES IN THE PRESENCE OF TITANIUM TETRACHLORIDE

The reaction of diversely substituted alpha-cyclopropylketones with al lyltrimethylsilane in the presence of titanium tetrachloride has been studied. The products formation is explained by the intervention of a cyclopropylcarbinyl transient cation formed after a first 1,2-addition on the carbonyl. With regard to the structure of the starting compoun ds, this intermediate reacts with a second molecule of allylsilane, ei ther by a bimolecular addition on the carbocycle, or by the direct att ack on the carbon bearing the formal positive charge yielding diallyl and functionalised cyclohexane derivatives. A general mechanism is pro posed.