Transient precursor states are often experimentally observed for molecules adsorbing on surfaces. However, such precursor states are typically rather short-lived, quickly yielding to more stable adsorption configurations. Here we employ first-principles calculations to systematically explore the interaction mechanism for benzene derivatives on metal surfaces, enabling us to selectively tune the...

The Ugi reaction is found to be a very powerful tool for the synthesis of (pre)tubulysin derivatives, allowing the introduction of various functionalized side chains in only one step. While polar groups such as amides are not well tolerated, unpolar side chains such as allyl or propargyl ether are well accepted. These functionalities also allow subsequent modifications in the side chain, e.g. v...

The EI mass spectra of four tert-butyldimethylsilyl ether derivatives of the major metabolite of prostaglandins F1 alpha and F2 alpha (PGF-M) are presented and discussed. Proposed ion assignments and fragmentation pathways are based on substituent shifts, on data from a deuterium-labeled methoxime analog, and on the analysis of collision-induced dissociation spectra of selected ions. Fragment i...

A simple method is described for the determination of molecular species of enantiomeric sn-1,2- and sn-2,3-diacylglycerols derived from natural triacylglycerols by Grignard degradation. The method is based on a preparative separation of the enantiomeric diacylglycerols as 3,5-dinitrophenylurethane (DNPU) derivatives by high performance liquid chromatography (HPLC) on a chiral column (25 cm x 4....

The effects of non-ionic surfactants as mobile phase additives on the fluorescence intensity of dansyl derivatives of biogenic amines in high-performance thin-layer chromatography (HPTLC) were investigated. The dansyl derivatives of putrescine, cadaverine, spermidine and spermine were separated by HPTLC with silica gel as stationary phase and an eluent consisting of chloroform–triethylamine (2 ...