Making more stable compounds out of less stable ones is nothing new, but going the other direction often requires multiple synthesis steps, harsh reaction conditions, and separating the desired products from the inevitable byproducts. Alison Wendlandt and co-workers have found a way around this obstacle, using a novel dual catalyst system (DOI: 10.1021/jacs.1c12043). Together with ultraviolet light, these catalysts convert conjugated alkenes and alkenes with double bonds in interiors of the carbon chains into their thermodynamically unfavored isomers: unconjugated, with double bonds between carbon atoms at the ends of the chains.
To demonstrate the technique, the researchers synthesized a variety of natural products, including an estrogen receptor agonist and several chiral linalool and terpene derivatives and isomers. Photochemistry provided access to excited electronic states, enabling an irreversible sequence of catalyst-driven intermediate oxidative addition and reductive elimination steps on the way to the final product. The compatibility of this method with such a wide variety of substrates indicates that the selectivity of the final products is largely governed by steric, rather than purely electronic, factors. This process can be applied to a wider variety of reactions than previous schemes that relied on catalytic or electronic processes alone.