Tryptamine Synthesis by Iron Porphyrin Catalyzed C−H Functionalization of Indoles with Diazoacetonitrile

The functionalization of C?H bonds with non‐precious metal catalysts is an important research area for the development of efficient and sustainable processes. Herein, we describe the development of iron porphyrin catalyzed reactions of diazoacetonitrile with N‐heterocycles yielding important precursors of tryptamines, along with experimental mechanistic studies and proof‐of‐concept studies of an enzymatic process with YfeX enzyme. By using readily available FeTPPCl, we achieved the highly efficient C?H functionalization of indole and indazole heterocycles. These transformations feature mild reaction conditions, excellent yields with broad functional group tolerance, can be conducted on gram scale, and thus provide a unique streamlined access to tryptamines.     

Zur Thermochemie der Kautschukvulkanisation

Ohne Zusammenfassung Dissertation von G. Schr?ter, Naturwissenschaftliche Fakult?t der Justus-Liebig-Hochschule (Gie?en 1956).     

Flux-enhanced monochromator by ultrasound excitation of annealed Czochralski-grown silicon crystals

The neutron flux from monochromator crystals can be increased by ultrasound excitation or by strain fields. Rocking curves of both a perfect float-zone silicon crystal and an annealed Czochralski silicon crystal with oxygen precipitates were measured at various levels of ultrasound excitation on a cold-neutron backscattering spectrometer. We find that the effects of the dynamic strain field from the ultrasound and the static strain field from the defects are not additive. Rocking curves were also taken at different ultrasound frequencies near resonance of the crystal/ultrasound-transducer system with a time resolution of 1 min. Pronounced effects of crystal heating are observed, which render the conditions for maximum neutron reflectivity delicate. Received: 19 October 2001 / Accepted: 7 March 2002 / Published online: 29 January 2003 RID="*" ID="*"Corresponding author. E-mail: andreas.magerl@krist.uni-erlangen.de     

Linear transformations on symmetric matrices that preserve the permanent

It is shown that if a linear transformation T on the space of n-square symmetric matrices over any subfield of the real field preserves the permanent, where n ? 3, then T(A)= ± PAP^t for all symmetric matrices A and a fixed generalized permutation matrix P with per P= ± 1.     

Communication: Vibrational spectroscopy of atmospherically relevant acid cluster anions: bisulfate versus nitrate core structures

Infrared multiple photon dissociation spectra for the smallest atmospherically relevant anions of sulfuric and nitric acid allow us to characterize structures and distinguish between clusters with a bisulfate or a nitrate core. We find that bisulfate is the main charge carrier for HSO(4)(-)·H(2)SO(4)·HNO(3) but not for NO(3)(-)·H(2)SO(4)·HNO(3). For the mixed dimer anion, we find evidence for the presence of two isomers: HSO(4)(-)·HNO(3) and NO(3)(-)·H(2)SO(4). Density functional calculations accompany the experimental results and provide support for these observations.     

Ground and low-lying excited states of propadienylidene (H2C=C=C:) obtained by negative ion photoelectron spectroscopy

A joint experimental-theoretical study has been carried out on electronic states of propadienylidene (H(2)CCC), using results from negative-ion photoelectron spectroscopy. In addition to the previously characterized X(1)A(1) electronic state, spectroscopic features are observed that belong to five additional states: the low-lying ?(3)B(1) and b(3)A(2) states, as well as two excited singlets, ?(1)A(2) and B(1)B(1), and a higher-lying triplet, c(3)A(1). Term energies (T(0), in cm(-1)) for the excited states obtained from the data are: 10,354±11 (?(3)B(1)); 11,950±30 (b(3)A(2)); 20,943±11 (c(3)A(1)); and 13,677±11 (?(1)A(2)). Strong vibronic coupling affects the ?(1)A(2) and B(1)B(1) states as well as ?(3)B(1) and b(3)A(2) and has profound effects on the spectrum. As a result, only a weak, broadened band is observed in the energy region where the origin of the B(1)B(1) state is expected. The assignments here are supported by high-level coupled-cluster calculations and spectral simulations based on a vibronic coupling Hamiltonian. A result of astrophysical interest is that the present study supports the idea that a broad absorption band found at 5450 ? by cavity ringdown spectroscopy (and coincident with a diffuse interstellar band) is carried by the B(1)B(1) state of H(2)CCC.     

Dipyrrolyl precursors to bisalkoxide molybdenum olefin metathesis catalysts

Addition of 2 equiv of lithium pyrrolide to Mo(NR)(CHCMe2R')(OTf)2(DME) (OTf = OSO2CF3; R = 2,6-i-Pr2C6H3, 1-adamantyl, or 2,6-Br2-4-MeC6H2; R' = Me or Ph) produces Mo(NR)(CHCMe2R')(NC4H4)2 complexes in good yield. All compounds can be recrystallized readily from toluene or mixtures of pentane and ether and are sensitive to air and moisture. An X-ray structure of a 2,6-diisopropylphenylimido species shows it to be an unsymmetric dimer, {Mo(NAr)(syn-CHCMe2Ph)(eta5-NC4H4)(eta1-NC4H4)}{Mo(NAr)(syn-CHCMe2Ph)(eta1-NC4H4)2}, in which the nitrogen in the eta5-pyrrolyl bound to one Mo behaves as a donor to the other Mo. All complexes are fluxional on the NMR time scale at room temperature, with one symmetric species being observed on the NMR time scale at 50 degrees C in toluene-d8. The dimers react with PMe3 (at Mo) or B(C6F5)3 (at a eta5-NC4H4 nitrogen) to give monomeric products in high yield. They also react rapidly with 2 equiv of monoalcohols (e.g., Me3COH or (CF3)2MeCOH) or 1 equiv of a biphenol or binaphthol to give 2 equiv of pyrrole and bisalkoxide or diolate complexes in approximately 100% yield.