Synthesis of Polyalkylphenyl Prop‐2‐ynoates and Their Flash Vacuum Pyrolysis to Polyalkylcyclohepta[b]furan‐2(2H)‐ones

A new method for the smooth and highly efficient preparation of polyalkylated aryl propiolates has been developed. It is based on the formation of the corresponding aryl carbonochloridates (cf. Scheme 1 and Table 1) that react with sodium (or lithium) propiolate in THF at 25 – 65°, with intermediate generation of the mixed anhydrides of the arylcarbonic acids and prop‐2‐ynoic acid, which then decompose almost quantitatively into CO₂ and the aryl propiolates (cf. Scheme 11). This procedure is superior to the transformation of propynoic acid into its difficult‐to‐handle acid chloride, which is then reacted with sodium (or lithium) arenolates. A number of the polyalkylated aryl propiolates were subjected to flash vacuum pyrolysis (FVP) at 600 – 650° and 10⁻² Torr which led to the formation of the corresponding cyclohepta[b]furan‐2(2H)‐ones in average yields of 25 – 45% (cf. Scheme 14). It has further been found in pilot experiments that the polyalkylated cyclohepta[b]furan‐2(2H)‐ones react with 1‐(pyrrolidin‐1‐yl)cyclohexene in toluene at 120 – 130° to yield the corresponding 1,2,3,4‐tetrahydrobenz[a]azulenes, which become, with the growing number of Me groups at the seven‐membered ring, more and more sensitive to oxidative destruction by air (cf. Scheme 15).     

Development and characterization of a small electromembrane extraction probe coupled with mass spectrometry for real-time and online monitoring of in vitro drug metabolism

A small and very simple electromembrane extraction probe (EME-probe) was developed and coupled directly to electrospray ionization mass spectrometry (ESI-MS), and this system was used to monitor in real time in vitro metabolism by rat liver microsomes of drug substances from a small reaction (incubation) chamber (37 °C). The drug-related substances were continuously extracted from the 1.0 mL metabolic reaction mixture and into the EME-probe by an electrical potential of 2.5 V. The extraction probe consisted of a 1-mm long and 350-μm ID thin supported liquid membrane (SLM) of 2-nitrophenyl octyl ether. The drugs and formed metabolites where extracted through the SLM and directly into a 3 μL min^?1 flow of 60 mM HCOOH inside the probe serving as the acceptor solution. The acceptor solution was directed into the ESI-MS-system, and the MS continuously monitored the drug-related substances extracted by the EME-probe. The extraction efficiency of the EME-probe was dependant on the applied electrical potential and the length of the SLM, and these parameters as well as the volume of the reaction chamber were set to the values mentioned above to avoid serious depletion from the reaction chamber (soft extraction). Soft extraction was mandatory in order not to affect the reaction kinetics by sample composition changes induced by the EME-probe. The EME-probe/MS-system was used to establish kinetic profiles for the in vitro metabolism of promethazine, amitriptyline and imipramine as model substances.     

Halodiazophosphonates, a new class of diazo compounds for the diastereoselective intermolecular Rh(II) catalyzed cyclopropanation

(Halodiazomethyl)phosphonates 2A-C have been generated by a one-pot procedure via a clean, efficient, and rapid deprotonation/electrophilic halogenation sequence from diethyl diazomethylphosphonate 1 (EDP). Subsequent intermolecular Rh(II)-catalyzed cyclopropanation afforded the corresponding halocyclopropylphosphonates 3-10 in moderate to high yields and high diastereomeric ratios. Catalyst loadings down to 0.1 mol % as well as clean and selective product formation were achieved.     

Electrochemical testing of composite electrodes of (La1?x Sr x ) s MnO3 and doped ceria in NO-containing atmosphere

The possibility of using electrochemical cells for removal of NO _x from an exhaust gas with excess O₂ has been examined. (La_1−x Sr _x ) _s MnO₃ (LSM) and ceria doped with Pr or Gd were selected as electrode materials and investigated in three-electrode cells. The electrodes were characterised electrochemically with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the gas composition monitored while the electrodes were polarised. The electrodes of (La_0.5Sr_0.5)_0.99MnO₃ (LSM50) and Ce_0.8Pr_0.2O_2−δ exhibit higher current densities in 0.1% NO in Ar than in air at 300 to 400 °C during CV. This indicates some apparent selectivity towards NO compared to O₂. The electrodes can remove NO, when polarised to at least −0.6 V vs. Pt/Air at 600 °C, and EIS measurements under polarisation indicate that the kinetics of the electrodes change, when the electrode potential gets below −0.6 V vs. Pt/Air.