An Asian wild ox is helping scientists in the fight against pesky mosquitoes. Researchers have succeeded in determining the exact structure of a compound that gaurs excrete as a mosquito deterrent and synthesizing it in the laboratory. The results could help control the spread of mosquitoes that carry tropical diseases, such as yellow fever and malaria.

Researchers had previously determined the basic building blocks of gaur acid--a ring made of four carbon atoms and one oxygen atom with two different side chains--but just how the atoms were arranged remained unclear. P. Andrew Evans of Indiana University and his colleagues designed a new synthesis that successfully recreated gaur acid. The feat was complicated because the molecule is chiral, which means that there are left- and right- handed versions that are mirror images but are not superposable, and only one of them is biologically active.

The chemists outline the synthesis reaction in the latest issue of the journal Angewandte Chemie International. The first step attaches the two future side chains to an oxygen atom to form a chain that is then closed in the second step to make a ring. By choosing different building blocks we can control both the ring size and the spatial arrangement of the side chains, Evans explains. The team confirmed that the reaction was successful by comparing how the synthetic compound bends light to results from gaur acid collected from animals.