My watch list
my.bionity.com  
Login  

Nitrogen gets in the fast lane for chemical synthesis

Chemists discover way to simplify synthesis of valuable precursor for drugs, other compounds

12-Feb-2019

Jeff Fitlow/Rice University

A one-step method by synthetic organic chemists at Rice University allows nitrogen atoms to be added to precursor compounds used in the design and manufacture of drugs, pesticides, fertilizers and other products.

Rice University scientists have given organic chemists a boost with their latest discovery of a one-step method to add nitrogen to compounds for drugs, pesticides, fertilizers and other products.

Rice synthetic organic chemist László Kürti said the method is a major step forward as it quickens and boosts the yield of valuable molecules known as alpha-aminoketones.

Ketones are carbon-based compounds found in nature and important feedstocks for the chemical industry. The primary amino group (NH2) is a functional group present in many important chemical products. It contains one nitrogen atom and two hydrogen atoms. When a ketone is functionalized with a primary amino group at the alpha carbon, it forms a compound called a primary alpha-aminoketone.

"It's a good precursor, because there's no extra functionalization, like an acyl group, on the NH2 and it can then be converted to whatever you want," said Kürti, an associate professor of chemistry. "Previously, this was the issue: People would put nitrogen in there with extra functionality, but the further processing necessary to get to a free NH2 was complicated."

Postdoctoral researcher Zhe Zhou discovered the reaction when he mixed a silyl enol ether and a nitrogen source in a common solvent, hexafluoroisopropanol, at room temperature and found that it mimicked Rubottom oxidation, an established technique to oxidize enol ethers.

"Oxygen is routinely put into the alpha position," Kürti said. "But nitrogen, no. We are the first to show this is possible in a large number of substrates, and it's simple. It turns out that the solvent itself catalyzes the reaction."

Zhou and co-author and postdoctoral researcher Qing-Qing Cheng refined the method and subsequently tested it by making 19 aminoketones, including three synthetic amino acid precursors. "These unnatural amino acids are significant for drug design," Kürti said. "The enzymatic processes in living organisms are not going to attack them, because they don't fit in the enzymes' pockets."

"Before we had this process, it wasn't impossible to make these kinds of structures," Zhou said. "It was just very complicated and took many steps. The goal, generally, is to get them by the most direct method possible."

Earlier synthetic processes by the Kürti lab eliminated the need for transition metal-based catalysts in the manufacture of amines in order to simplify the usual and often inefficient trial-and-error approach involved in making new chemical compounds like drugs. Metal-based catalysts that speed up amination - the introduction of amine groups to an organic molecule -- can also contaminate the product, so the new process avoids them as well.

"Our amination method promises to replace a common three-step process to make alpha-aminoketones, and the yield, comparably, is very good," Zhou said. "In the standard process, each step cuts the yield, so one-step process is still superior even if the yields are identical, because it takes less time and there's less risk of something going wrong.

"The last thing you want is to get eight steps from the beginning and then ruin it on the ninth because the conditions are not selective enough," he said. "Cutting steps is always beneficial in organic synthesis."

"There's a new trend toward late-stage functionalization, where companies with an existing library of compounds can take 100 of them and perform an additional step to make 100 new compounds," he said. "So from an intellectual property perspective, our discovery is a great gift to industry. This really is a gem of a find."

Facts, background information, dossiers
  • nitrogen
  • catalysts
  • drugs
  • aminoketones
More about Rice University
  • News

    Iron outperforms gadolinium as MRI contrast agent

    Rice University nanoscientists have demonstrated a method for loading iron inside nanoparticles to create MRI contrast agents that outperform gadolinium chelates, the mainstay contrast agent that is facing increased scrutiny due to potential safety concerns. "The possibility of eliminating ... more

    A new way to target flu virus

    There's a hitch in the swing of a protein that delivers the flu virus. Rice University and Baylor College of Medicine researchers believe this mechanism may be a useful target to stop the virus from infecting cells. The Rice-Baylor team led by biophysicist José Onuchic and biochemists Jianp ... more

    Social context matters in spread of disease

    "Patient zero" isn't entirely to blame when an infection takes root in a population. According to Rice University scientists, social context in the community has a lot to do with how a disease spreads. Rice researchers who study fruit flies found that the ratio of females to males as well a ... more

  • Universities

    Rice University

    Located on a 285-acre forested campus in Houston, Texas, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Scienc ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE