Fig. 2: The dinuclear addition of a Pd^I–Pd^I moiety to substituted 1,3-dienes.

a The dinuclear addition to 5-methylhexa-2,4-dienoate (2), and subsequent dinuclear elimination giving Z-diene selectively. b ORTEP for 3-transoid-antifacial (30% probability ellipsoids; counteranions are omitted for clarity). c The allyl π–σ–π interconversion for the rapid stereoinversion mechanism. d The ligand survey for stereoretentive elimination of Z-2. The reactions were carried out in CD₃NO₂ at room temperature. dppm = bis(diphenylphosphino)methane. [a] At −30 °C. e Yields of Z-1,3-dienes after isolation. Typically, the diene was added to a CH₃NO₂ solution of 1, and stirred for 30 min. The reaction mixture was cooled to −30 °C, and then COT was added and the mixture was stirred for 15 min. [b] PPh₄I was used instead of COT.