Gold(I) as an Artificial Cyclase: Short Stereodivergent Syntheses of (−)‐Epiglobulol and (−)‐4β,7α‐ and (−)‐4α,7α‐Aromadendranediols

Three natural aromadendrane sesquiterpenes, (?)‐epiglobulol, (?)‐4β,7α‐aromadendranediol, and (?)‐4α,7α‐aromadendranediol, have been synthesized in only seven steps in 12, 15, and 17 % overall yields, respectively, from (E,E)‐farnesol by a stereodivergent gold(I)‐catalyzed cascade reaction which forms the tricyclic aromadendrane core in a single step. These are the shortest total syntheses of these natural compounds.     

On the Reactivity of (−)‐(R)‐Carvone and (−)‐4aα,7α,7aβ‐Nepetalactone: Synthesis of New Heterocycles

The 1,3‐dipolar cycloaddition of 4‐chlorobenzonitrile oxide to the unsaturated system of (?)‐(R)‐carvone occurred exclusively at C(8) to give a new isoxazoline derivative. This derivative reacts with NH₂OH to yield a new heterocycle, observed for the first time. On the other hand, the addition of 4‐chlorobenzonitrile oxide to the unsaturated lactone (?)‐4aα,7α,7aβ‐nepetalactone gave, in a good yield, also a new heterocycle, again obtained for the first time. The terpenoid (?)‐(R)‐carvone and iridoid (?)‐4aα,7α,7aβ‐nepetalactone were isolated from Moroccan species Mentha viridis (L.) and Nepeta tuberosa (L.), respectively. The new heterocycles obtained were identified by combination of chromatographic and spectroscopic methods.     

Titelbild: A Phosphorus Analogue of Bis(η4‐cyclobutadiene)iron(0) (Angew. Chem. 17/2009)

Ein Phosphoranalogon des Komplexes Bis(η⁴‐cyclobutadien)eisen(0) wird von K. Lammertsma et al. in ihrer Zuschrift auf S. 3150 ff. vorgestellt. Im Hintergrund des Titelbilds posiert John Montagu (1718–1792), 4th Earl of Sandwich und Erster Lord der Admiralität, der es sich sicherlich nicht hätte träumen lassen, dass eines Tages eine wichtige Klasse von Organometallverbindungen nach ihm benannt werden würde. Die Synthese von [Fe(P₂C₂tBu₂)₂] belegt, dass die Sandwich‐Komplexe immer noch ein aktuelles Forschungsgebiet sind.