Cerium saves money to make drug precursor

Save your money! It is better used for jewelry than as a catalyst for drugs.

Scientists at Rice University have developed a greatly simplified method of making fluoroketones, precursors for the design and manufacture of drugs that typically require a silver catalyst.

Rice chemist Julian West and graduate students Yen-Chu Lu and Helen Jordan introduced a process for the rapid and scalable synthesis of fluoroketones that were heretofore difficult and expensive to manufacture.

Their open access work covers the February 21 issue of the journal of the Royal Society of Chemistry ChemComm.

The lab’s new process replaces silver with cerium-based ceric ammonium nitrate (CAN), which produces functional precursors under mild conditions in about 30 minutes.

“We could make batches of it in a tub,” West said.

Cerium has shown such potential in other labs, and the fact that it is 800 times more abundant in the earth’s crust than silver made it of great interest to Rice’s team.

“Ketones are a bridge functional group in molecules that you can use to make different things, like anti-cancer compounds,” said West, who came to Rice in 2019 with funding from the Cancer Prevention and Research Institute of Texas and was named Forbes. 30 Under 30, science was a game changer last year.

“They’re a great starting point for turning into an alkene or an aromatic ring,” he said. “The important part of this article is that we are incorporating fluorine into these fragments. Fluoride is an interesting element and quite abundant, but it is hardly used in biology.

“Fluorine has extreme properties – it’s incredibly electronegative, so it holds back its electrons,” West said. “This makes it difficult for enzymes in biological processes to process them into pharmaceuticals like anticancer molecules.”

Hydrogen atoms in drug molecules are easy for the liver to process, but replacing them with fluorine “is like shielding in this position,” he said. “It helps the drugs last much longer in the body, so you don’t have to take that much. This is desirable for chemotherapy.” He noted that atorvastatin (aka Lipitor), one of the most commonly prescribed drugs in the United States, contains fluoride for the same purpose.

“We want to put fluorine in specific places on the molecule where we know it will make a difference, and this ketone functional group allows us to do that,” West said. “People use a silver catalyst, but the process requires a lot of money, it takes a long time at high temperatures, and it has to be done under a carefully controlled nitrogen or argon atmosphere.

“Our process is cheap bucket chemistry, and we believe the reaction takes about five minutes,” he said. “But we’re leaving it for 30, just to be safe.”

The process is highly scalable. “When Yen-Chu tripled the original recipe, he got exactly the same result,” West said. “It’s rare in these kinds of reactions.”