Mao Mao#, Ling Zhang#, Yao-Zhong Chen, Jie Zhu, Lei Wu*, Palladium-Catalyzed Coupling of Allenylphosphine Oxides with N-Tosylhydrazones toward Phosphinyl [3]Dendralenes
ACS Catalysis, 2017,7, 181-185.
(SCI IF2016: 10.614, Open Access, Designated as ACS Editor’s Choice,“ESI Highly Cited Paper”)
A palladium-catalyzed coupling of allenylphosphineoxides with N-tosylhydrazones, leading to phosphinyl[3]dendralenes, is established. The coupling reaction can becatalyzed by bis(triphenylphosphine)palladium chloride withsodium pivalate as a key additive, presumably via π-allyl-Pdcarbeneintermediates. This protocol provides an expedientsynthesis of unprecedented multisubstituted phosphinyl [3]-dendralenes with a broad substrate diversity and dominant Z-stereoselectivity,depending on the substitution positions. X-ray crystallographic analyses confirm the relative stereochemistry ofproducts and reveal multiple double bonds in a phosphinyl [3]dendralenes array with a “fanlike” dimensional orientation. Furtherapplications of phosphinyl [3]dendralenes to intramolecular cyclization and selective oxidation demonstrate the differentiatedreactivities of double bonds.