Biomimetic studies towards the cardinalins: synthesis of (+)-ventiloquinone L and an unusual dimerisation.

Studies towards the biomimetic synthesis of cardinalin 3 are described. Despite the successful enantioselective synthesis of the monomeric pyranonaphthoquinone ventiloquinone L, it subsequently failed to undergo a proposed biomimetic homodimerisation to cardinalin 3 using a range of oxidants. However, treatment of a related naphthopyran with cerium ammonium nitrate (CAN) facilitated a tandem biaryl bond formation-oxidative demethylation sequence furnishing a dimeric pyranonaphthoquinone that had exclusively dimerised at C6. The nature of this unusual sequence is discussed and the product subsequently converted to the C6 regioisomer of cardinalin 3.

Aluminium Electrodeposition from Ionic Liquid: Effect of Deposition Temperature and Sonication †.

Since their discovery, ionic liquids (ILs) have attracted a wide interest for their potential use as a medium for many chemical processes, in particular electrochemistry. As electrochemical media they allow the electrodeposition of elements that are impossible to reduce in aqueous media. We have investigated the electrodeposition of aluminium from 1-butyl-3-methyl-imidazolium chloride ((Bmim)Cl)/AlCl3 (40/60 mol %) as concerns the effect of deposition parameters on the quality of the deposits. Thick (20 µm) aluminium coatings were electrodeposited on brass substrates at different temperatures and mixing conditions (mechanical stirring and sonication). These coatings were investigated by means of scanning electron microscope, roughness measurements, and X-ray diffraction to assess the morphology and the phase composition. Finally, electrochemical corrosion tests were carried out with the intent to correlate the deposition parameters to the anti-corrosion properties.