Flash-metathesis for the coupling of sustainable (poly)hydroxyl β-methylstyrenes from essential oils

A cross-metathesis procedure was developed to synthetize symmetrical and non symmetrical stilbenes from sustainable resources. The reaction proceeds under solvent-free conditions and at low catalyst loading (down to 0.01 mol%) within a couple of minutes only (TOF up to 6.9 s⁻¹), on multi-gram scale. The highly reactive β-methylstyrene substrates were homo-coupled not only as pure synthons but also as components of essential oils that were reacted directly in order to eliminate prior substrate isolation from the overall process.