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 CHAMPAIGN -- One of the fundamental
challenges facing organic synthesis in the 21st century is the need
to significantly increase the efficiency with which carbon
frameworks can be constructed and functionalized. Chemists at the
University of Illinois are helping to meet this challenge by
developing a class of carbon-hydrogen catalysts that are highly
selective, reactive and tolerant of other functionality.
The catalysts also offer a new strategy for streamlining the
synthesis of important compounds, including drugs and
pharmaceuticals, by avoiding the functional group manipulations
required for working with oxidized materials.
"We are creating a toolbox of catalytic reactions that allow us to
go directly from a carbon-hydrogen bond to a carbon-oxygen bond or
to a carbon-nitrogen bond," said M. Christina White, a professor of
chemistry at Illinois.
"By offering fewer steps, fewer functional group manipulations and
higher yields, this toolbox will change the way chemists make
molecules."
Currently, chemists must make molecules by beginning with something
that is already oxidized. But, having to start with that
functionality means it must be carried – and protected – throughout
the entire synthetic sequence. And that costs reagents, time, money
and manpower, in addition to being inherently inefficient.
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"Unlike standard synthetic methods, we don't have to carry the
functionality throughout the entire sequence," White said. "Instead,
we carry latent functionality as a carbon-hydrogen bond. Then, at a
late stage in the synthesis, we remove the hydrogen and replace it
with oxygen or nitrogen – right where we need it for the next
chemical reaction."
In the June 13 issue of the Journal of the American Chemical
Society, White and graduate student Kenneth J. Fraunhoffer describe
the catalytic pathway they used to synthesize a derivative of the
chemotherapeutic reagent acosamine. They were able to eliminate all
of the functional group manipulations and cut by one-half the number
of steps required, while maintaining the same purity and yield.
White has also used her catalyst to streamline the synthesis of a
peptidase inhibitor drug candidate, a nucleotide-sugar L-galactose,
and is currently working on the antibiotic erythromycin A.
White's research is funded by the Henry Dreyfus Foundation, the A.P.
Sloan Foundation, the University of Illinois, Merck Research
Laboratories, the National Institutes of Health and the National
Science Foundation.
[Text copied from
University
of Illinois news release]
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