In the high-stakes world of drug discovery, building a new medicine is a lot like microscopic architecture. To create the next breakthrough antibiotic or brain-targeting therapy, chemists must snap together fragile molecular building blocks. But for decades, one of the most useful chemical pieces has been notoriously stubborn, requiring conditions so harsh they often destroy the very medicine being built. Now, researchers have found a way to pick the lock.
[Hebrew University of Jerusalem]– In a new study published in Nature Communications, a team of chemists has unveiled a radically simple way to attach a highly sought-after “molecular handle”, known as the dichloromethyl group, onto complex compounds. Instead of relying on the aggressive, heavy-metal or radiation-heavy techniques of the past, the team used a common, naturally occurring amino acid called proline to gently choreograph the assembly.
“Rather than forcing these molecules into conventional reactivity modes or circumventing their electronic ambivalence, we harnessed their electronic ambivalence as a design principle," says Prof. Dmitry Tsvelikhovsky, who led the research team at the Institute for Drug Research at the Hebrew University, alongside Elihay Kuniavsky and Dvora R. Levy.
A Built-In Quality Control
The dichloromethyl group is highly prized by pharmaceutical chemists because it acts as an anchor point, allowing researchers to tweak and expand a molecule’s structure to make it safer or more effective. Until now, inserting this anchor into delicate molecules was considered a chemical dead end.
The Hebrew University team bypassed this roadblock by using proline as a tiny “molecular machine.” Rather than relying on brute chemical force, proline temporarily binds to the target molecule and guides it into a highly specific shape. This precise alignment naturally shifts the molecule's internal electronics, enabling it to seamlessly incorporate the new chemical handle.
The most striking discovery, however, lies in the reaction's built-in self-correction system, which the team calls a "stereochemically gated" resolution. As proline engages with the starting material, it presents two distinct three-dimensional arrangements. It's like having two keys for a lock, one perfect and one subtly misshapen. Critically, the reaction is so precisely designed that only the perfectly configured arrangement is allowed to proceed, seamlessly forming the desired, ultra-pure product. The other, subtly mismatched arrangement, is elegantly shunted into a harmless, non-reactive state and simply reverts to its original components during cleanup. This sophisticated chemical "gatekeeper" ensures unparalleled purity and selectivity, preventing unwanted byproducts and dramatically simplifying the synthesis of complex drug compounds.
Building the Drugs of Tomorrow
The implications of this new chemical platform are vast. The team has already proven that their method works directly on the molecular frameworks used to build next-generation antibiotics, natural products, and neuroactive compounds, such as those that interact with serotonin receptors in the brain.
By turning a decades-old chemical impasse into a programmable, reliable platform, this discovery gives medicinal chemists a powerful new tool for designing, testing, and manufacturing life-saving therapies that were previously thought impossible to build.
The research paper titled “Proline-Promoted Electrophilic Dichloromethylation of α-Enaminones via Stereochemically Gated Resolution” is now available in Nature Communications and can be accessed at https://doi.org/10.1038/s41467-026-71815-z.
Prof. Dmitry Tsvelikhovsky
(Credit: School of Pharmacy, Faculty of Medicine, HUJI)
Researchers:
Elihay Kuniavsky, Dvora Rachel Levy, and Dmitry Tsvelikhovsky
Institutions:
The Institute for Drug Research, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel