N EWS O F T H E W E E K
TWO-BY-TWO TO ZARAGOZIC ACID
compound that acts as a building block for glycolic acid, a two-carbon α-hydroxy acid. “We took a look at zaragozic acid and saw that its core contains a series of three consecutive glycolic acid fragments,” Johnson explains. ORGANIC CHEMISTRY: Two-carbon The group’s reagent, a silyl glyoxylate, has an electroreagent helps build natural product’s philic functional group and a latent nucleophilic group. core while reducing redox steps A trigger reagent unmasks the glyoxylate’s nucleophilic moiety, which can then react with a second glyoxylate molecule, leading to a chain-building cascade. To build zaragozic acid C, the team manipulated reY TAKING A PAGE from polymer chemistry, agent ratios to precisely control the number of glyoxylresearchers have completed a new synthesis of ates added to the chain. Because the glyoxylate reagent the natural product zaragozic acid C, a fungal is already in the correct oxidation state for building metabolite named after the Spanish city Zaragoza. The zaragozic acid C, it minimized the number of redoxnew route relies on a versatile two-carbon building related steps in the synthesis, Johnson says. block and could inspire highly efficient routes to myriJohnson’s oligomerization strategy is likely to exad natural products featuring repeating subunits. tend to an array of natural products and analogs that have repeating motifs, says Daniel Romo, an OH O organic chemist at Texas A&M O O Cascade University. “The caveat, as with OH R´O reaction CO2R RO2C R´ O RO2C most methods, is that this parO OR´ CO R 2 ticular reagent is only applicable CO2H O R = tert-butyl to a subset of natural products,” CO2H R´ = tert-butyldimethylsilyl O HO2C he says. But that should inspire OH chemists to develop reagents that A TRIPLE DOUBLE Linking three copies of a Zaragozic acid C complement Johnson’s versatile two-carbon building block makes an important glyoxylate, he adds. portion (red) of the core of zaragozic acid C. “The Johnson group has provided a stunning example of the power of carefully orchestrated multiple-bondSeveral research groups have synthesized zaragozic forming cascade reactions to deliver highly complex acids, which block cholesterol biosynthesis. But the products—in this case, a major portion of the core ring highly oxygenated core ring system in these comsystem of the zaragozic acids—from extraordinarily pounds remains particularly challenging to assemble. simple starting materials,” says James L. Leighton, a Now, David A. Nicewicz, Andrew D. Satterfield, Daniel professor at Columbia University who has synthesized C. Schmitt, and Jeffrey S. Johnson of the University of other natural products with repeating building blocks, North Carolina, Chapel Hill, have developed a reaction that fashions the core’s three adjoining chiral centers in such as polyacetates and polypropionates. “The oftused descriptor ‘elegant’ is insufficient in this case to one step (J. Am. Chem. Soc., DOI: 10.1021/ja808347q). do justice to the beauty and quality of this work.”— The key transformation was made possible by a reagent that Johnson’s group had already developed—a CARMEN DRAHL
B
FUNDING Department of Energy chooses Michigan State University for rare-isotope facility The Department of Energy has selected Michigan State University to design and establish the Facility for Rare Isotope Beams (FRIB). MSU’s selection for the new $550 million project marks the first step toward development of a U.S. facility for rare-isotope beams, which have applications in basic research and medicine. FRIB will be a national user facility supported by DOE’s Office of Science and will accommodate approximately 1,000 researchers. When completed in about
10 years, FRIB will join three other DOEsponsored facilities in the U.S. capable of producing rare isotopes and will complement other facilities around the world. The MSU facility “promises to vastly expand our understanding of nuclear astrophysics and nuclear structure,” Eugene Henry, acting associate director of DOE’s Office of Science for Nuclear Physics, said in a press release. “This capability will allow physicists to study the nuclear reactions that power stars and
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stellar explosions, explore the structure of the nuclei of atoms and the forces that bind them together, test current theories about the fundamental nature of matter, and play a role in developing new nuclear medicines and techniques.” The facility will utilize a high-power, heavy-ion linear accelerator driver, a gas catcher to collect the reaction fragments, and a postaccelerator to reaccelerate the rare species for a wide variety of experiments.—ROCHELLE BOHATY
