Crystal and Molecular Structure of [2,6‐(Me2NCH2)2C6H3]2SnF2, an Intramolecularly Coordinated Diorganotin Difluoride

Single‐crystal X‐ray diffraction analysis of [2,6‐(Me₂NCH₂)₂C₆H₃]₂SnF₂ reveals that only one of the two dimethylaminomethyl groups of each pincer‐type ligands [2,6‐(CH₂NMe₂)₂C₆H₃]^? is coordinated to the tin atom at Sn‐N distances of 2.576(2) and 2.470(2) Å, inducing chirality of the latter. The tin atom exhibits a distorted octahedral trans(C,C)cis(N,N)cis(F,F) configuration. Extensive intra‐ and intermolecular C‐H···F hydrogen bonding is observed with the latter giving rise to formation of polymeric chains.     

Edge-to-face CH/pi aromatic interaction and molecular self-recognition in epi-cinchona-based bifunctional thiourea organocatalysis

The impact of cooperativity between intermolecular interactions is demonstrated by the molecular self-recognition properties of highly enantioselective epi-cinchona bifunctional thiourea organocatalysts. Low-temperature NMR experiments in inert solvents have revealed two sets of nonequivalent resonances in equal population for thiourea-modified members of the epi-quinine and epi-quinidine families. In solution, the predominance of an asymmetric (C1) dimeric self-assembly with noteworthy structural motifs became evident: simultaneous intra- and intermolecular thiourea hydrogen bonding and a CH/pi interaction were observed. Both the stereochemical and the diverse conformational features of the system favor the observed quinoline T-shaped aromatic pi-pi stacking interaction. The structure findings are supported by quantitative proton-proton distance data that were available from NOE buildup curves. The 3D structure of the dimeric assembly has been modeled in agreement with the H-H distance restraints. Owing to the geometrical preference associated with the dimerization process, the self-assembled bifunctional system is interpreted as a charge-transfer complex with the potential for catalyst self-activation.     

One-pot reactions of nitroenamines with anilines and ethyl glyoxylate

In a simple, one-pot, catalyst-free procedure starting from heterocyclic nitroenamines, substituted anilines and ethyl glyoxylate new ethyl 2-arylamino-3-nitro-propionates were prepared in good to excellent yields. Depending on the substituent pattern of the anilines applied, two routes for the one-pot reaction are suggested. Additionally, it was demonstrated that these multifunctional compounds of aza-Morita–Baylis–Hillman type were also formed in two-step protocols either from imines and nitroenamines or from the adducts of nitroenamines and ethyl glyoxylate with anilines.     

Phase‐Transfer‐Catalysed Synthesis of Pyrroloindolines and Pyridoindolines by a Hydrogen‐Bond‐Assisted Isocyanide Cyclization Cascade

A cascade reaction that generates pyrrolo‐ and pyridoindoline motifs from isocyanide precursors under phase‐transfer conditions is described. This transformation proceeds at room temperature in the presence of a quaternary ammonium catalyst and base to generate functionalized products containing an all‐carbon quaternary stereocentre. Quantum chemical calculations demonstrated that intramolecular general acid catalysis plays a key accelerating role through stabilization of developing charge in the transition state, and that the reaction is best described as a 5‐endo dig cyclization, rather than an anionic 6π electrocyclization. Investigations employing chiral phase‐transfer catalysts have given promising selectivities to date.     

Photopolymers for Rapid Prototyping of Soluble Mold Materials and Molding of Cellular Biomaterials

Summary. To substitute cross-linked photopolymers in rapid prototyping of mold materials and therefore extend the range of materials which can be casted, organo-soluble photopolymers were developed. Branched bisalkylacrylamides were suitable as base component for such formulations, due to their high reactivity, good mechanical properties, and excellent solubility of the formed polymers. These molding materials were used to prepare cellular biocompatible materials which could be used as bone replacement materials. Biocompatible crosslinkers based on methacrylates from hydrolyzed gelatine or lactic acid ethyleneglycol blockcopolymers and commercially available reactive diluents are the base components of such a formulation. Biocompatibility was investigated by osteoblast-like cells. Cellular biocompatible parts were obtained by thermal polymerization in soluble mould materials prepared by 3D-photoshaping.     

Investigation of the HDS kinetics of dibenzotiophene and its derivatives in real gas oil ??

Summary The hydrodesulfurization (HDS) of dibenzothiophene (DBT), 4-methyl-dibenzothiophene (4 M-DBT), 4,6-dimethyldibenzothiophene (4,6 DM-DBT) and 4,6-diethyldibenzothiophene (4,6 DE-DBT) as real gas oil components on NiMo/Al₂O₃ catalyst was investigated. On the basis of the first order rate constants of HDS of the individual sulfur compounds calculated by both integral and differential evaluations the reactivities of the investigated compounds decreased in the order DBT >> 4 M-DBT > 4,6 DE-DBT ? 4,6 DM-DBT. Additionally, results showed that product inhibition during HDS does not take place.     

Simple route to new oxadiazaboroles and oxadiazoles via amidoximes

Abstract

The novel push–pull alkene, the 2-(nitro-nitrosomethylene)-pyrrolidine with numerous aliphatic or aromatic amines as nucleophiles afforded amidoximes. Various substituted oxadiazaborole and oxadiazole derivatives were prepared starting from these amidoximes, widening the synthetic applicability of the push–pull alkenes. Acylation of the amidoximes was also examined. The mechanism of the amidoxime formation was investigated by computational methods.