Synthesis of substituted benzooxaborinin-1-ols via palladium-catalysed cyclisation of alkenyl- and alkynyl-boronic acids

Two new palladium-catalysed reactions have been developed for the synthesis of stable 4-substituted benzooxaborinin-1-ols. A palladium-catalysed cyclisation of ortho-alkenylbenzene boronic acids can be used to access 4-chlorobenzooxaborinin-1-ols via a Wacker-type oxidation and chlorination. Alternatively, ortho-alkynylbenzene boronic acids undergo a palladium-catalysed oxyallylation reaction to provide 4-allylbenzooxaborinin-1-ols

Divergent prebiotic synthesis of pyrimidine and 8-oxo-purine ribonucleotides

Understanding prebiotic nucleotide synthesis is a long standing challenge thought to be essential to elucidating the origins of life on Earth. Recently, remarkable progress has been made, but to date all proposed syntheses account separately for the pyrimidine and purine ribonucleotides; no divergent synthesis from common precursors has been proposed. Moreover, the prebiotic syntheses of pyrimidine and purine nucleotides that have been demonstrated operate under mutually incompatible conditions. Here, we tackle this mutual incompatibility by recognizing that the 8-oxo-purines share an underlying generational parity with the pyrimidine nucleotides. We present a divergent synthesis of pyrimidine and 8-oxo-purine nucleotides starting from a common prebiotic precursor that yields the β-ribo-stereochemistry found in the sugar phosphate backbone of biological nucleic acids. The generational relationship between pyrimidine and 8-oxo-purine nucleotides suggests that 8-oxo-purine ribonucleotides may have played a key role in primordial nucleic acids prior to the emergence of the canonical nucleotides of biology

Sonochemical synthesis of nano-cocrystals

Cocrystals are multicomponent solids with organic molecules assembled in combination to form a crystalline solid with properties different than the individual components. A cocrystal typically consists of a target molecule crystallized with a second molecule, or cocrystal former, employed to influence properties of the target (e.g. solubility). The conformer interacts with the target via intermolecular forces (e.g. hydrogen bonds) that hold the components together. The modularity of a cocrystal makes such solids attractive for applications where fine-tuning of properties is important (e.g. optical). In this presentation, we describe the use of sonochemistry to form cocrystals of nanoscale dimensions. In contrast to single-component solids, cocrystals present a fundamentally different challenge with respect to those reprecipitation methods used to form nanocrystals since the components of a cocrystal will tend to exhibit different solubilities. We show that sonochemistry affords nano-cocrystals with properties (e.g. reactivity) that contrast solids of macroscale dimensions. Related applications of sonochemistry to afford singlecomponent nanocrystals will also be presented. © 2013 Acoustical Society of America