Andrew W. Thomas

The GABA_B positive allosteric modulator (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (1) was synthesized in one pot from the anhydrous lithium salt of 2,4-di-tert-butylphenol and methyl trifluoropyruvate mediated by a stoichiometric amount of anhydrous gallium(III) chloride in 64% overall yield. The enantiomers of 1 were separated by chiral-phase HPLC (Chiralpak AD®), and the absolute configuration was determined by X-ray crystallography.

Novel and straightforward syntheses (3-5 steps, high yields) of racemic diazaspiropiperidine derivatives based on the Michael addition of pipecolate-derived enolates to a range of nitroalkenes have been developed. The reaction has been shown to have a general scope and can be conducted on a preparatively useful scale. Isolation and identification of diazaspiropiperidine enantiomers was efficiently achieved using normal phase chiral HPLC.

Kupfer‐vermittelte C(Aryl)‐N‐, C(Aryl)‐O‐ und C(Aryl)‐S‐ Verknüpfungen sind Kupplungsreaktionen mit einer großen Bandbreite an Substraten. In dieser Hinsicht ergänzt diese Methode die Palladium‐vermittelten Arylierungsreaktionen. Hier beschreiben wir neue Entwicklungen bei stöchiometrischen und katalytischen Varianten der Reaktionen mit Arylboronsäuren, Arylhalogeniden, Iodoniumsalzen, Siloxanen, Stannanen, Plumbanen, Bismutaten und Trifluoroboraten als Aryldonoren. Erst kürzlich wurden Arylboronsäuren als Reaktionspartner für die O‐ und N‐Arylierung eingeführt; dieser Klasse von Aryldonoren wird in diesem Aufsatz besondere Aufmerksamkeit gewidmet. Durch die Verwendung unterschiedlicher Kupferquellen und Basen sowie zusätzlicher Liganden und Additive konnten deutliche Verbesserungen erzielt werden. Mechanistische Untersuchungen sollen Aufschluss über die katalytisch aktiven Spezies geben und so zur Entwicklung milderer Methoden mit größerer Effizienz führen. Der Aufsatz umfasst die Literatur bis Ende April 2003.

The copper‐mediated C(aryl)N, C(aryl)O, and C(aryl)S bond formation is an important transformation and has been developed to include a wide range of substrates. This Review highlights the recent developments in the copper‐mediated (both stoichiometric and catalytic) reactions of aryl boronic acids, aryl halides, iodonium salts, siloxanes, stannanes, plumbanes, bismuthates, and trifluoroborate salts as aryl donors. In particular, the recent introduction of boronic acids as reaction partners in both O‐ and N‐arylation has been a significant discovery and will occupy centre‐stage in this review. Clear improvements can be obtained by the correct choice of copper source, base, ligands, and other additives. Mechanistic investigations should provide insight into the catalytically active species, which would aid in the development of milder, more‐efficient methods.

Using a polymer-supported phosphine-mediated intramolecular aza-Wittig reaction in a key step of a reaction sequence a diverse library of benzodiazepine-quinazolinone alkaloids (Circumdatins) has been prepared using a novel modified Eguchi protocol. The multi-arrayed library generation strategy commenced from readily accessible benzodiazepinedione derivatives (and anthranilic acids) and all library members were purified by reverse phase preparative HPLC.