NEWS OF THE W EEK
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ACILE SYNTHESIS of promising tetrazine bio-
chemical probes could be a big step forward for researchers who examine biochemistry as it happens in cells and live animals (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201201117). The advance, utilizing Lewis acid catalysts, might allow more researchers to make the probes in one pot from commercially available starting materials. Thus far, the tetrazine labels, which feature nitrogen-rich rings, have been relegated to labs with the chemistry chops to work with the multistep and low-yielding syntheses required to make them. Researchers who are looking deeply at biochemistry as it happens value these and other so-called bioorthogonal coupling agents because they can monitor a particular target while avoiding side reactions with the stew of other cellular components. Tetrazines, in particular, are prized for their selectivity and speed in reacting with cyclooctene labels. However, the most convenient tetrazine synthesis requires two steps: nucleophilic addition of hydrazine to a nitrile followed by oxidation. That synthesis doesn’t work for
ACS HONORS LEGISLATORS AWARDS: 2012 Public Service Award goes to three champions of science and engineering policy
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HE AMERICAN CHEMICAL SOCIETY present-
ed its 2012 Public Service Award to Rep. Roscoe Bartlett (R-Md.), Sen. Christopher Coons (DDel.), and former Sen. Ted Kaufman (D-Del.) during a ceremony on Capitol Hill on April 24. “Tonight’s honorees exemplify the role that policymakers can play in supporting innovation, providing opportunity, and helping others,” said ACS Board Chair William F. Carroll Jr., who presented the awards. Bartlett is one of three scientists in Congress and a senior member of the House of Representatives Science, Space & Technology Committee. He has been a strong supporter of defense science and technology and is currently cochair of the STEM (science, technology, engineering, and mathematics) Education Caucus.
CARMEN DRAHL
Coons was instrumental in passing the America Invents Act in 2011, designed to make U.S. scientists more competitive globally. He also introduced the Job Creation Through Innovation Act, which proposed making the research and development tax credit permanent, and he introduced the 2011 International Year of Chemistry Senate Resolution. “Thank you to ACS for this award, and thank you for your voice and your engagement with the Congress of the United States, and thank you for continuing to stand up for science and stand up for its role in the future of our country,” Coons said. Kaufman, who served as a Bartlett senator from 2009 to 2010, secured $400,000 to fund research and extension grants for women and minorities in STEM. He also authored the STEM Education Coordination Act, which recognized all federal programs and activities that support STEM education. He thanked ACS for not only providing Congress with the facts, but also being “excellent advocates for the issues that you determine to be important.”—LINDA WANG
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OFFICE OF SEN. COONS
synthesis of biochemical probes
Coons OFFICE OF SEN. KAUFMAN
ORGANIC CHEMISTRY: Lewis acids ease
alkyl nitriles, and syntheses from other precursors, such as amidine salts, are low-yielding. Now, a team led by Neal K. Devaraj of the University of California, San Diego, has streamlined tetrazine production with Lewis acid catalysts such as nickel triflate. The Lewis acids are thought to bind to the nitrile or hydrazine. This promotes the first step in tetrazine synthesis enough to get results with alkyl nitriles and swap an oxidative workup for the separate oxidation step. Devaraj’s group used their technique to make unsubstituted tetrazines and asymmetric tetrazines; the latter are so named because they have two different substituents. “We have had problems generating such compounds using traditional techniques, so this method is certainly welcomed,” says Joseph P. A. Harrity, a chemist at the University of Sheffield, in England. However, he points out that it might be challenging to separate some asymmetric tetrazines from symmetric by-products. So far, separations have been straightforward, but improvements to cut down on troublesome by-products are in the works, Devaraj says. For example, he elaborates, “we plan on tweaking the procedure by immobilizing one nitrile on a solid support and reacting it with another nitrile in solution.” Devaraj notes the new synthesis should be useful not only to biochemists but also to materials scientists and explosives researchers, who use tetrazines as well.—
OFFIC E OF REP. BARTLET T
STREAMLINING TETRAZINE SYNTHESIS
Kaufman
