Stille Cross‐Coupling of a Racemic Planar‐Chiral Ferrocene and Crystallographic Trace Analysis of Catalysis Intermediates and By‐products

A pressure‐controlled procedure for the S_N1 reaction of rac‐1‐[(dimethylamino)methyl]‐2‐(tributylstannyl)ferrocene ( 1 ) to rac‐1‐(phthalimidomethyl)‐2‐(tributylstannyl)ferrocene ( 2 ) was developed. Pd⁰‐Catalyzed Stille coupling of 2 with iodobenzene afforded rac‐1‐phenyl‐2‐(N‐phthalimidomethyl)ferrocene ( 5 ) in 74% yield; after trace enrichment by crystallization of the combined mother liquors, one single crystal of each, 5 , catalysis intermediate trans‐iodo(σ‐phenyl)bis(triphenylarsino)palladium(II) ( 7 ), trans‐diiodobis(triphenylarsino)palladium(II) ( 8 ), and rac‐2,2′‐bis(phthalimidomethyl)‐1,1′‐biferrocene ( 9 ) could be isolated by crystal sorting under a microscope and characterized by X‐ray crystal structure analysis. Furthermore, 5 was deprotected to amine ( 11 ), which does even survive the Birch reduction to rac‐1‐(aminomethyl)‐2‐(cyclohexa‐2,5‐dienyl)ferrocene ( 12 ).     

"Safe" Coulomb excitation of 30Mg

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."     

Eine neue Methode zur Bestimmung des Theobromins in Diuretin, Calcium-Diuretin, Jod-Calcium-Diuretin und Rhodan-Calcium-Diuretin

Ohne Zusammenfassung     

Sum factorization of the static condensed Helmholtz equation in a three-dimensional spectral element discretization

We propose a factorization technique for the Helmholtz operator of a static condensed, three-dimensional, cartesian spectral-element discretization, that yields linear complexity in the number of degrees of freedom. We then compare its performance to a reference implementation of the conventional, unfactorized approach. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mechanistic Characterisation of Two Sesquiterpene Cyclases from the Plant Pathogenic Fungus Fusarium fujikuroi

Two sesquiterpene cyclases from Fusarium fujikuroi were expressed in Escherichia coli and purified. The first enzyme was inactive because of a critical mutation, but activity was restored by sequence correction through site‐directed mutagenesis. The mutated enzyme and two naturally functional homologues from other fusaria converted farnesyl diphosphate into guaia‐6,10(14)‐diene. The second enzyme produced eremophilene. The absolute configuration of guaia‐6,10(14)‐diene was elucidated by enantioselective synthesis, while that of eremophilene was evident from the sign of its optical rotation and is opposite to that in plants but the same as in Sorangium cellulosum. The mechanisms of both terpene cyclases were studied with various ¹³C‐ and ²H‐labelled FPP isotopomers.     

Testing Born’s Rule in Quantum Mechanics for Three Mutually Exclusive Events

We present a new experimental approach using a three-path interferometer and find a tighter empirical upper bound on possible violations of Born’s Rule. A deviation from Born’s rule would result in multi-order interference. Among the potential systematic errors that could lead to an apparent violation we specifically study the nonlinear response of our detectors and present ways to calibrate this error in order to obtain an even better bound.