Practical and Convenient Synthesis of 1,6-Di- or 1,2,5,6-Tetra-arylhexa-1,3,5-trienes by the Dimerization of Pd(0)-Complexed Alkenylcarbenes Generated from π‑Allylpalladium Intermediates

Pd­(0)-complexed
3-aryl or 2,3-diaryl propenylcarbenes generated
from α-silyl-, α-germyl-, or α-boryl-σ-allylpalladium
intermediates undergo self-dimerization to provide 1,6-di- or 1,2,5,6-tetraarylhexa-1,3,5-trienes
in good to high yields. This method allows the use of a π-allylpalladium
intermediate for a carbenoid precursor. Furthermore, the obtained
1,2,5,6-tetraarylhexa-1,3,5-trienes exhibit aggregation-induced emission
enhancement property.