Microwave-enhanced carbonylative generation of indanones and 3-acylaminoindanones

The development of microwave-accelerated protocols for palladium(0)-catalyzed carbonylative cyclization of unsaturated aryl bromides and chlorides is described. By employing o-bromostyryl derivatives lacking substituents on the vinylic bond, molybdenum hexacarbonyl-mediated in situ carbonylation delivered a set of indan-1-one products in high yield after only 20 min of heating. Without the addition of the tri-tert-butylphosphine releasing Fu-salt ((t-Bu)(3)PHBF(4)), only incomplete conversions of sluggish o-styryl bromides and chlorides were realized. Internal and chemoselective palladium(0)-catalyzed Heck arylations of enamides afforded suitable starting materials for subsequent rapid ring-closing reactions. Microwave-heated intramolecular in situ carbonylation of these electron-rich and sterically congested olefins conveniently afforded eight functionalized 3-acylaminoindanone derivatives in a novel synthetic process. Attempted carbonylative annulation of electron-poor o-bromocinnamic acid derivatives furnished only the corresponding lactones via a competing hydroxycarbonylation-Michael addition reaction sequence.     

Protein identification platform utilizing micro dispensing technology interfaced to matrix-assisted laser desorption ionization time-of-flight mass spectrometry

An integrated protein microcharacterization/identification platform has been developed. The system has been designed to allow a high flexibility in order to tackle challenging analytical problems. The platform comprises a cooled microautosampler, an integrated system for microcolumn HPLC, and a capillary reversed-phase column that is interfaced to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) system via a low internal volume flow-through microdispenser. The chromatographic separation is continuously transferred onto a MALDI target plate as discrete spots as the dispenser ejects bursts of droplets of the column effluent in a precise array pattern. A refrigerated microfraction collector was coupled to the outlet of the flow-through microdispenser enabling enrichment and re-analysis of interesting fractions. The use of target plates pre-coated with matrix simplified and increased the robustness of the system. By including a separation step prior to the MALDI-TOF-MS analysis and hereby minimizing suppression effects allowed us to obtain higher sequence coverage of proteins compared to conventional MALDI sample preparation methodology. Additionally, synthetic peptides corresponding to autophosphorylated forms of the tryptic fragment 485-496 (ALGADDSYYTAR) of tyrosine kinase ZAP-70 were identified at sensitivities reaching 150 amol.     

The level structure of92Ru up to high spin values

The level structure of⁹²Ru has been studied by means of γ-ray spectroscopy. The nucleus was produced by the⁵⁸Ni(⁴⁰Ca, α2p)⁹²Ru reaction at beam energies of 147 and 187 MeV. The NORDBALL detector system including particle selection was used. A large number of new levels with excitation energies up to 11.3 MeV and spin values up to 22 or 23 units of angular momentum have been established. The level scheme is compared with recent shell model calculations using¹⁰⁰Sn as a core. Some systematics of the g ₉ ^2/?2 configuration is discussed and a strong correlation between the levels in⁹⁰Mo and⁹²Ru is found.     

Syntheses of Theaspirone and Vitispirane via Palladium(II)-Catalyzed Oxaspirocyclization

Total syntheses of theaspirone (A and B) and vitispirane (A and B) are described. The key step in the syntheses is the palladium(II)-catalyzed intramolecular oxaspirocyclization of diene alcohol 4 to either vitispirane or the allylic alcohol 9. The outcome of the oxaspirocyclization is very much dependent on the solvent employed. In water-acetic acid (4:1) a 1:1 mixture of the diastereomeric alcohols 9A and 9B was exclusively formed. In water with 8 equiv of a strong non-nucleophilic acid, vitispiranes A and B (1:1) were obtained. An alternative procedure to obtain vitispirane with the use of LiCl and K(2)CO(3) is described. In the latter reaction vitispirane B is formed preferentially. This result is explained by an equilibrium between the two possible pi-allyl complexes 5A and 5B, the kinetically favored 5B being transformed into vitispirane 3B before isomerization to 5A occurs.     

Flow-through microdispenser for interfacing micro-HPLC to Raman and mid-IR spectroscopic detection

A flow-through microdispenser has been coupled to a micro HPLC separation system and used as a solvent elimination interface for Fourier transform infrared (FTIR) and Raman spectroscopic detection of the separated compounds. Using the microdispenser picoliter sized droplets can be generated and deposited on an appropriate target placed on a computerized x, y-stage. Evaporation of volatile solvent and buffer is rapid and allows analysis of the obtained dry deposits by various techniques. Due to the destruction free character of Raman and FTIR spectroscopy they can be applied sequentially to interrogate the same deposit. In the reported application five phenolic acids typically present in wine have been separated on a C-18 column technique using a mixture of water, methanol and acetic acid as mobile phase. For spectrum acquisition infrared and Raman microscopes have been used. The spectra recorded from the dried deposits of the separated compounds agreed well with the reference spectra of corresponding components.