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The synthesis of a tricyclic N-nucleoside analogue in which an ethano bridge linked the urea NH group with the ring junction of the bicyclic tetrahydrofuropyran unit is described. Topological information observed from the structure led to the choice of an ethano bridge tethering the proximal urea nitrogen atom with [C.sub.3] at the junction of the perhydrofuropyran ring system.

An enantioselective synthesis of the antifungal natural product (+)-ambruticin S is achieved starting with the me thyl [alpha]-D-glucopyranoside, (R)-Roche ester, and (S)-glycidol as chirons, which has encompassed seven of the 10 stereogenic centers of the target molecule. The strategy for the construction of the dihydropyran subunit has involved a highly syn-selective Lewis acid catalyzed 6-endo-trig cyclization and other key steps in the synthesis has featured an epoxide opening with a dithiane anion, two efficient phosphonamide-anion based olefinations, and a late-stage C-glycosylation.

The importance of functional group orientations and the integrity of the bicyclic perhydrofuran core of malayamycin A and its N-nucleoside analogues as fungicides are examined. Molecular dynamics studies are performed in order to highlight the importance of properly orienting the urea and methyl ether groups.

Photoredox cycling during UV irradiation of ferrocyanide ([FeII(CN)6]4−) in the presence of stoichiometric sulfite (SO32−) is shown to be an extremely effective way to drive the reductive homologation of hydrogen cyanide (HCN) to simple sugars and precursors of hydroxy acids and amino acids. [ABSTRACT FROM AUTHOR]

When considering life's aetiology, the first questions that must be addressed are "how?" and "where?" were ostensibly complex molecules, considered necessary for life's beginning, constructed from simpler, more abundant feedstock molecules on primitive Earth. Previously, we have used multiple clues from the prebiotic synthetic requirements of (proto)biomolecules to pinpoint a set of closely related geochemical scenarios that are suggestive of flow and semi-batch chemistries. We now wish to report a multistep, uninterrupted synthesis of a key heterocycle (2-aminooxazole) en route to activated nucleotides starting from highly plausible, prebiotic feedstock molecules under conditions which mimic this scenario. Further consideration of the scenario has uncovered additional pertinent and novel aspects of prebiotic chemistry, which greatly enhance the efficiency and plausibility of the synthesis. [ABSTRACT FROM AUTHOR]

Described are our preliminary studies on the reactivity of thiophosphate in a setting which correlates with the cyanosulfidic systems chemistry we have previously reported. Thiophosphate adds to various nitrile groups giving the corresponding thioamides in a highly efficient manner and the mechanistic implications are briefly discussed. Thiophosphate can also act as a phosphorylating agent, which was demonstrated with adenosine. The prebiotic availability of thiophosphate must be questioned, but if a plausible synthesis can be found, the advantages it would bring to the field of prebiotic chemistry appear to be highly beneficial. [ABSTRACT FROM AUTHOR]

A minimal cell can be thought of as comprising informational, compartment-forming and metabolic subsystems. To imagine the abiotic assembly of such an overall system, however, places great demands on hypothetical prebiotic chemistry. The perceived differences and incompatibilities between these subsystems have led to the widely held assumption that one or other subsystem must have preceded the others. Here we experimentally investigate the validity of this assumption by examining the assembly of various biomolecular building blocks from prebiotically plausible intermediates and one-carbon feedstock molecules. We show that precursors of ribonucleotides, amino acids and lipids can all be derived by the reductive homologation of hydrogen cyanide and some of its derivatives, and thus that all the cellular subsystems could have arisen simultaneously through common chemistry. The key reaction steps are driven by ultraviolet light, use hydrogen sulfide as the reductant and can be accelerated by Cu(I)-Cu(II) photoredox cycling. [ABSTRACT FROM AUTHOR]

Biophysical studies of ligand interactions with three human telomeric repeat sequences (d(AGGG(TTAGGG)n, n = 3, 7 and 11)) show that an oxazole-based 'click' ligand, which induces parallel folded quadruplexes, preferentially stabilises longer telomeric repeats providing evidence for selectivity in binding at the interface between tandem quadruplex motifs. [ABSTRACT FROM AUTHOR]

A recent synthesis of activated pyrimidine ribonucleotides under prebiotically plausible conditions relied on mixed oxygenous and nitrogenous systems chemistry. As it stands, this synthesis provides support for the involvement of RNA in the origin of life, but such support would be considerably strengthened if the sugar building blocks for the synthesis-glycolaldehyde and glyceraldehyde-could be shown to derive from one carbon feedstock molecules using similarly mixed oxygenous and nitrogenous systems chemistry. Here, we show that these sugars can be formed from hydrogen cyanide by ultraviolet irradiation in the presence of cyanometallates in a remarkable systems chemistry process. Using copper cyanide complexes, the process operates catalytically to disproportionate hydrogen cyanide, first generating the sugars and then sequestering them as simple derivatives. [ABSTRACT FROM AUTHOR]

A silver-mediated one-step procedure to 2,4-disubstituted and 2,4,5-trisubstituted oxazoles has been developed. The method is complementary to existing technologies, yet provides advantages with regard to simplicity, efficiency, and performance. The silver product can be readily recycled, thus minimizing waste. [ABSTRACT FROM AUTHOR]

A synthetic approach towards the structurally complex dimer, kingianin A is reported. The strategy involved a cascade of complexity generating reactions, inspired through biosynthetic speculation. A concise protecting group free synthesis of the proposed monomeric precursor pre-kingianin A has been achieved using a tandem Stille cross-coupling reaction and electrocyclisation process. However, preliminary studies of the key dimerisation reaction have been conducted, which indicate that the process is not spontaneous, raising questions as to the origin of this complex natural product., (This journal is © The Royal Society of Chemistry 2011)

Described is the structure-based design and synthesis of a series of tris-triazole G-quadruplex binding ligands utilising the copper catalysed azide-alkyne 'click' reaction. The results of G-quadruplex stabilisation by the ligands are reported and discussed.

Described is the first modular construction of a G-quadruplex chiral catalyst. The key objective was to use G-quadruplex structures to act as chiral ligands that would allow access to either enantiomer of the product of a Diels-Alder reaction.

An indium mediated procedure has been developed for the allylation of activated O-functionalised oximes and nitriles as exemplified by a variety of glyoxylate derivatives. This method gives the corresponding free (or protected) amine in a one pot-process. The method is regiospecific and is carried out under remarkably mild conditions so that even oxime esters can be subjected to the typical reaction conditions.