Fluorescence-based screening of asymmetric acylation catalysts through parallel enantiomer analysis. Identification of a catalyst for tertiary alcohol resolution

A technique for high-throughput screening of kinetic resolution catalysts is reported. The method relies on carrying simultaneous kinetic resolutions in a multiwell plate format wherein each well contains a unique catalyst and a small amount of a pH-activated fluorescent sensor (3). By conducting experiments such that each catalyst is evaluated in parallel in the presence of each isolated enantiomer, an indication of catalyst activity is obtained on a per enantiomer basis. Catalysts that are highly active for one enantiomer but modestly active for another are then reevaluated in conventional kinetic resolutions. From these screens, a highly selective (k(rel) = 46) pentapeptide (4) was obtained for a model secondary alcohol (1). In addition, peptide 10 was found to afford excellent selectivities (k(rel) > 20) for a number of alcohol substrates (9a-9f) in the traditionally challenging tertiary class.     

Essential oil composition of three Australian endemic species of Darwinia (Myrtaceae)

The essential oils from the aerial parts of three rare Australian endemic species of Darwinia have been extracted by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC-MS). In D. procera, myrtenyl acetate (6.1-29.6%), alpha-pinene (6.9-25.1%), gamma-terpinene (6.2-13.6%), bicyclogermacrene (5.5-10.8%) and (E)-nerolidol (3.4-9.7%) were the principal components detected. D. fascicularis ssp. fascicularis produced an oil in which (E)-nerolidol (33.0%), alpha-pinene (15.1%) and gamma-terpinene (10.2%) were the principal components. In D. peduncularis the major constituents were alpha-pinene (33.5%), gamma-terpinene (23.1%) and bicyclogermacrene (6.7%).