Abstract: The reaction of tetrachloromethane with magnesium under general Grignard reaction condition was studied. It is found for the first time to produce dichlorocarbene which is trapped with different olefins to prepare gem-dichlorocyclopropane derivatives in good yields, The reaction having the advantages of easy work-up,mild reaction condition and high yield is a convenient method for the generation of dichlorocarbene. Apossible mechanism (single electron transfer,SET)was proposed. The solvent effects on the reaction were studied.

Key words: Dichlorocarbene, Gem-dichlorocyclopropane, Single electron transfer(SET)