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Reaction between terminal alkynes and phenyl iodides bearing a tethered alkyne unit can be effectively controlled by the nature of a transition metal catalyst. Whereas the use of Pd(0)/Cu(I) promotes the expected Sonogashira coupling to give phenyl alkynes, the absence of the copper co-catalyst triggers a palladium-mediated cyclisation providing 1,2-dihydroacenaphthylene, 1H,3H-benzo[de]isochromene, (1Z)-1-(2-propynylidene)-2,3-dihydro-1H-indene and (4E)-4-(2-propynylidene)-3,4-dihydro-1H-isochromene derivatives. In the latter Pd-catalysed two-component process, the product distribution depends on the structure of alkyne-substituted phenyl iodides, terminal alkynes and secondary amines used as solvents. The proposed reaction mechanism reflects a competitive formation of intermediary σ-(acetylide) vs π-alkyne Pd(II) complexes. [Copyright &y& Elsevier]

Abstract: A synthesis of new bidentate pyridines 8a–d, 9, and 10 has been developed, starting from triflate 14, readily available from β-pinene 11. A copper complex of the pyridine–oxazoline ligands 8a has been found to catalyze asymmetric allylic oxidation of cyclic olefins 36a–c with good conversion rates and acceptable enantioselectivity (≤67% ee). The imidazolium salt 10 has been identified as a precursor of the corresponding N,N′-unsymmetrical N-heterocyclic carbene ligand, whose complex with palladium catalyzed the intramolecular amide enolate α-arylation leading to oxindole 45 in excellent yield but with low enantioselectivity. [Copyright &y& Elsevier]

Abstract: A protocol for rapid and highly modular assembly of a diverse set of helquats is described. From a common bis-isoquinoline precursor, two successive distinct pyridine-type nitrogen quaternizations followed by rhodium-catalyzed [2+2+2] cycloaddition afford non-symmetric [7]helquats. This route allows for straightforward molecular editing of cationic helical skeletons as exemplified by the synthesis of 15 different [5]-, [6]-, and [7]helquats. [Copyright &y& Elsevier]

Abstract: Ruthenium-catalyzed substitutions of carbon pronucleophiles, various [2+2+2] cycloadditions, and addition of a diazo compound to an alkyne are shown to proceed in the presence of air. Notably diverse catalytic manifolds remain supported under conditions generally regarded as prohibitive. Building on rare reports from the literature we show that a range of organometallic transformations based on reaction intermediates derived from (C5Me5)Ru or (C5H5)Ru moieties are air-compatible. [Copyright &y& Elsevier]