the shift: The title reaction of a propargylic bis(carbonate) with diboron compounds leads to new cross‐conjugated polymers 1 having 2,3‐butadienylene moieties. 1 is then converted into the linear‐conjugated polymers 2 through a Diels–Alderreaction. The fluorescent spectra of the cis‐linked polymers 2 show large Stokes shifts compared to those of the cross‐conjugated polymer precursors 1.
An efficient cross-coupling reaction using a low cost carbon-supported palladium (Pd/C) catalyst for the synthesis of cross-conjugated compounds, diaryl[n]dendralenes, has been developed. The reaction of a propargylic biscarbonate with phenylboronic acid using Pd/C and phosphine ligand (S-Phos) gave 2,3-diphenyl[2]dendralene in high yield. We found that Pd/C was an effective catalyst for the synthesis of dialyl[n]dendralenes. The synthesis of various dendralenes was successfully achieved under the optimized conditions, giving dialyl [2] and [4] dendralenes in good yields. (C) 2017 Elsevier Ltd. All rights reserved.