dl-Selective reductive coupling/Dieckmann condensation sequence of α,β-unsaturated amides with samarium(II) iodide/HMPA. Synthesis of a new ligand, trans-1,2-cyclopentanediyl-2,2'-biphenol

Article abstract of DOI:10.1016/0040-4039(96)01951-X

By action of SmI₂-HMPA in THF, the N,N-dimethyl derivatives of (E)-α,β-unsaturated amides produce the 1,2-trans-2,3-trans stereoisomers of 2,3-disubstituted 5-oxo-1-cyclopentane-carboxamides via a highly dl-selective reductive coupling followed by Dieckmann condensation. Water-d₂ is an effective quenching agent. This reaction is successfully applied to the synthesis of trans-1,2-cyclopentanediyl-2,2'-biphenol, which is a new C₂-symmetric chiral ligand.