Abstract: This review summarizes previous mechanistic studies on reactions of dihalocarbenes with carbonyl compounds where dihalocarbonyl Ylide was suggested to be the intermediate.The structural factors such as steric effects of substrates,electronic effects of substituents,Captodative effect of the carbonyl Ylide intermediate,and radius of the halogen atoms that influence the stabilities and conformations of the dihalocarbonyl Ylides and their following reaction pathways are also discussed.

Key words: Carbonyl Ylide, Deoxygenation, Dihalocarbene