Carbon-Carbon Bond-Forming Reactions Using Cerium Metal or Organocerium(III) Reagents

Article abstract of DOI:10.1021/jo00195a006

Carbon-carbon bond-forming reactions using cerium metal or organocerium(III) reagents have been investigated.Cerium amalgam is an effective reagent for the chemoselective preparation of homoallylic alcohols from allyl halides and carbonyl compounds.These same reagent can also be satisfactorily employed for the Reformatsky-type reaction of α-halo esters with carbonyl compounds.It has been shown that organocerium(III) reagents are conveniently generated by the reaction of organolithiums with cerium(III)iodide or cerium(III)chloride.The reagents are less basic thanorganolithiums or Grignard reagents, and they react cleanly at -78 to -65 deg C with various carbonyl compounds to afford the addition products in high yields, even though the substrates are susceptible to enolization or metal-halogen exchange with simple organolithiums.The same reagents react also with α,β-unsaturated compounds to yield 1,2-addition products in high selectivity.