Polymer-Supported Synthesis of Stilbenes

Significance

A small library of fluorescent and unsymmetrical trans-stilbenes was prepared by solid-phase synthesis using a sulfonate-based traceless linker system. Thus, the Suzuki-Miyaura coupling of polymer-supported 4-bromobenzenesulfonate (1) and 4-formylphenylboronic acid (2) with Pd(PPh₃)₄ gave polymer-bound 4-formyl­biphenylsulfonate 3. The Horner-Wadsworth-­Emmons reaction of 3 and benzylphosphonates 4 ­followed by the Kumada-Tamao-Corrium-type coupling with aryl Grignard reagents 6 afforded the corresponding unsymmetrical stilbenes 7 in 37-50% yield (three steps from 1; 9 examples).