text: Organocerium reagents are used almost exclusively for addition reactions in the same vein as organolithium and Grignard reagents.They are highly nucleophilic, allowing additions to imines in the absence of additional Lewis acid catalysts, making them useful for substrates in which typical conditions fail.
  Despite this high reactivity, organocerium reagents are almost entirely non-basic, tolerating the presence of free alcohols and amines as well as enolizable α-protons.
  They undergo 1,2-addition in reactions with conjugated electrophiles. At the same time, organocerium reagents can be used to synthesize ketones from acyl compounds without over-addition, as seen with organocuprates.
  Organocerium reagents have been employed in a number of total syntheses. Shown below is a key coupling step in the total synthesis of roseophilin, a potent antitumor antibiotic.