Location: Fifth Floor, West Wing, North Wall, Sequence 7
Source: Professor Leonard
Sponsor: Arnold C. Ott
Leonard has been a leader in the application of organic synthesis to important problems in biology. In particular, he recognized that synthetic molecular probes could provide critical information about the active sites of enzymes. For example, his findings on the reaction of diethyl pyrocarbonate with adenosine and its nucleotides resulted in its use as a chemical probe to identify structural details in DNA (cruciform loops, left-handed helices, etc.). Especially important were his preparations of fluorescent derivatives of nucleosides, nucleotides and coenzymes. His synthesis of 1,3,4,6-tetraazapentalenes was crucial to the construction of covalently-linked cross sections with molecular architecture similar to H-bonded DNA/RNA base pairs for both anti-parallel and parallel helical duplexes. If phosphorylated and incorporated in a polynucleotide sequence, these sections can introduce local rigidity and distortions of known dimensions as markers for potential alteration of biological activity.
In earlier work, Leonard made major contributions to transannular reactions of medium sized ring N- and S-containing ketones, and to other areas of heterocyclic chemistry. He coauthored well over 400 research publications.
Leonard was born in Newark, NJ, obtained the Ph.D. at Columbia University (1942) and spent his academic career at the University of Illinois (1942-86). Since 1992 he has been a Faculty Associate at Cal Tech. His many honors include election to the National Academy of Sciences (1955), the ACS Award for Creative Work in Synthetic Organic Chemistry (1963) and the Roger Adams Award (1981).