News | May 14, 1999

Aromatic Ring Reaction Named For Australian Scientist

Andy Liepa, chief research scientist with the Molecular Science Division of Australia's Commonwealth Scientific and Industrial Research Organization (Csiro; Clayton, Victoria; (+) 61-039-545-2576) has just had a chemical reaction named after him. The process, now called "Liepa phenanthrenes synthesis," controls the behavior of aromatic rings, making it quicker and easier to reproduce certain naturally occurring chemicals in a laboratory. Aromatic rings have a wide range of industrial uses in making dyes, drugs, plastics, and many other chemicals.

About The Process

About The Process (Back to Top)
Liepa developed the process, which involves a breakthrough in controlling the behavior of a carbon compound known as an aromatic ring, while he was a postdoctoral fellow in the U.S. during the early 1970s. He went on to further demonstrate its use while he was a research fellow at the ANU in the mid-1970s and later at Csiro Molecular Science.

"Aromatic rings play a very important role in organic chemistry as they form the building blocks of many complex substances," Liepa says. The most basic of these is the benzene ring, which consists of six atoms of carbon in a flat hexagonal shape that have a hydrogen atom attached to each one. The bonds between the carbon atoms are very strong, which makes the structure very stable, yet aromatic rings are able to react with other chemicals.

Liepa says that while procedures have been developed for many kinds of chemical reactions, methods to form direct links between aromatic rings such as benzene have been few and inefficient.

"I found a chemical which was able to overcome this. This chemical had a strong affinity with electrons, and was able to remove one from the ring. This meant we were able to form a highly reactive chemical intermediate," Liepa says. "This could then be used to carry out chemical syntheses difficult to achieve by conventional chemical methods."

Applications (Back to Top)
Liepa says that the process has been particularly valuable in simplifying the preparation of several alkaloids. Alkaloids are organic compounds that are most commonly found in certain plants. Many alkaloids are biologically active, and a significant number are important in medicine for a variety of applications such as relieving pain, lowering blood pressure, and treating cancer, gout, and malaria.

"This means that in theory the process could have significant use in the production of medicines, particularly where there is not enough of a naturally occurring product to make production commercially viable," Liepa says.

The process was recently a key method used in the U.S. to produce the antibiotic Vancomycin. Vancomycin has become more important in recent years because it has become the treatment of last resort against antibiotic-resistant strains of golden staph (Staphylococcus aureus) which have emerged as a widespread and potentially lethal threat during hospitalization.

In addition to these applications, the procedure has been used as one of the key methods for synthesizing a number of natural products.

Liepa's contribution will appear in the second edition of "Organic Syntheses Based on Name Reactions and Unnamed Reactions" by A. Hassner and C. Stumer.

For more information, call Liepa at CSIRO at (+) 61-039-545-2576, or e-mail