Rhodium-catalyzed 1,4-addition of alkenylzirconocene chlorides to electron deficient alkenes

The 1,4-conjugated addition of alkenylzirconocene chloride complexes to α,β-enones, α,β-enoic acid esters, and α,β-enoic acid amides can be efficiently achieved by the use of [RhCl(cod)]2 catalyst. A high diastereoselectivity (95% yield, 90% de) was obtained through the reaction of α,β-enoic acid amide derived from Oppolzerʹs sultam and 2-butenoyl chloride, while the use of Evansʹ chiral oxazolidinone as a chiral auxiliary in place of Oppolzerʹs sultam gave a poor diastereoselectivity (98% yield, 26% de).