The kinetics and mechanism of ligand substitution reactions of [Pt(SMC)Cl(2)] (SMC = S-methyl-l-cysteine) with biologically relevant ligands were studied as a function of chloride and nucleophile concentrations at pH 2.5 and 7.2. It was observed that the slope and intercept obtained from the linear dependence of the observed rate constant on the nucleophile concentration strongly depend on the ...

For studies of RNA structure, folding, and catalysis, site-specific modifications are typically introduced by solid-phase synthesis of RNA oligonucleotides using nucleoside phosphoramidites. Here, we report the preparation of two complete series of RNA nucleoside phosphoramidites; each has an appropriately protected amine or thiol functional group. The first series includes each of the four com...

We report a new class of catalytic reaction: the thermal substitution of a secondary and or tertiary alkyl halide with a nitrogen nucleophile. The alkylation of a nitrogen nucleophile with an alkyl halide is a classical method for the construction of C-N bonds, but traditional substitution reactions are challenging to achieve with a secondary and or tertiary alkyl electrophile due to competing ...

The development of the new chiral ligands for use in asymmetric catalytic reactions has drawn considerable interest in the last 10 years. In this area, palladiumcatalyzed allylic substitution reactions have been shown to be effective tools for the construction of carbon-carbon and carbon-heteroatom bond1 formation, and several efficient enantioselective catalysts such as C2and C1symmetric biden...

PERSPECTIVES AND SUMMARY ................... ... ...................................................... 877 Classes of enzyme involving reactions at phosphorus...................................................... 878 COVALENT REACTION INTERMEDIATES, CRYPTIC AND OTHERWISE........................................................................................................ 879 Reactions of Pho...

Depending on the selected DFT functional, two different mechanisms are found for two organic reactions (an intramolecular nucleophilic aromatic substitution and a nucleophilic addition on a carbonyl moiety). Indeed, B3LYP predicts a concerted mechanism whereas M06-2X foresees a multistep one. Calculations at the MP4(SDQ) level proved the mechanisms to be stepwise. We studied these reactions wit...

Lewis acid mediated substitution reactions using [D]triethylsilane as a nucleophile at the anomeric center of the four pentofuranoses, ribose, arabinose, xylose, and lyxose, all proceed with good to excellent stereoselectivity to provide the 1,2-cis adducts. To unravel the stereoelectronic effects underlying the striking stereoselectivity in these reactions we have mapped the energy landscapes ...

A catalyst system for the Stille cross-coupling reactions of aryl mesylates and tosylates is reported. Using the combination of Pd(OAc)2, XPhos, and CsF in t-BuOH an array of aryl and heteroaryl sulfonates were successfully employed in these reactions. Morever, heteroarylstannanes, such as furyl, thiophenyl, and N-methylpyrrole, which are often prone to decomposition, were efficiently coupled u...

A highly efficient, chemoselective synthesis of a library of polysubstituted pyrroles and tetrahydropyridines has been achieved through the one-pot, multicomponent reactions of ethyl (E)-3-(aryl/alkyl amino) acrylates, 2,2-dihydroxy-1-arylethan-1-ones, and malononitrile under solvent- and catalyst-free grinding conditions. The selective formation of pyrrole or tetrahydropyridines relied on subs...