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Nucleosides represent one of the key building blocks of biochemistry. There is significant interest in the synthesis of nucleoside‐derived materials for applications as probes, biochemical models, and pharmaceuticals. Palladium‐catalyzed cross‐coupling reactions are effective methods for making covalent modification of carbon and nitrogen sites on nucleobases under mild conditions. Water‐soluble catalysts derived from palladium and hydrophilic ligands, such as tris(3‐sulfonatophenyl)phosphine trisodium (TPPTS), are efficient catalysts for a range of coupling reactions of unprotected halonucleosides. Over the past two decades, these methods have been extended to direct functionalization of halonucleotides, as well as RNA and DNA oligonucleotides (ONs) containing halogenated bases. These methods can be run under biocompatible conditions, including examples of Suzuki coupling of modified DNA in whole cells and tissue samples. In this account, development of this methodology by our group and others is highlighted along with the extension of these catalyst systems to modification of nucleotides and ONs.

 

Palladium catalysts have become central to modern organic synthesis, particularly in the context of cross‐coupling reactions to form C−C and C‐heteroatom bonds. The development of highly efficient catalyst systems has seen a transition from the use of in situ‐generated catalysts derived from a ligand source and palladium precursor to the use of preformed palladium‐ligand complexes that can efficiently generate the active species. The design of these systems has focused on optimizing the generation of the LPd(0) species presumed to be the active catalysts with most state‐of‐the‐art ligand systems. This review will highlight the development of Pd(0), Pd(I), and Pd(II) precatalysts that efficiently generate LPd(0) active species with a focus on their activation mechanisms and applications in catalysis.

 

With NSF MRI support, we have recently purchased a dual source single crystal diffractometer equipped with a high resoln. detector.  The purpose of this presentation is to publicize the new instrument and we seek users in the Southeast to maximize the pos. impact of this instrument on research efforts in the Southeastern US.  Users at primarily undergraduate institutions and historically black colleges and universities are particularly encouraged to use this new resource.  In general, an X-ray diffractometer allows accurate and precise measurements of the full three-dimensional structure of a mol., including bond distances and angles, and provides accurate information about the spatial arrangement of a mol. relative to neighboring mols.  The studies described here impact many areas, including org. and inorg. chem., materials chem. and biochem.  This instrument is an integral part of teaching as well as research and research training of graduate and undergraduate students in chem. and biochem. at this institution and at partner institutions.  This poster will describe some examples of how the new diffractometer will enhance research in inorg. chem., materials chem. (via diffuse scattering), and biochem.