text: As reagents in organic chemistry, organocerium compounds are typically prepared in situ by treatment of cerium trichloride with organolithium or Grignard reagent. Reagents are derived from alkyl, alkynyl, and alkenyl organometallic reagents as well as enolates have been described. The most common cerium source for this purpose is cerium (III) chloride, which can be obtained in anhydrous form via dehydration of the commercially available heptahydrate. Precomplexation with tetrahydrofuran is important for the success of the transmetallation, with most procedures involving "vigorous stirring for a period of no less than 2 hours".   The structures depicted (as below) for organocerium reagent, however are highly simplified.
  These reagents add 1,2 to conjugated ketones and aldehydes. This preference for direct addition is attributed to the oxophilicity of the cerium reagent, which activates the carbonyl for nucleophilic attack.