Weak O‐Assistance Outcompeting Strong N,N‐Bidentate Directing Groups in Copper‐Catalyzed C−H Chalcogenation

A copper‐mediated C?H chalcogenation of triazoles has been achieved by weak coordination. The user‐friendly protocol showed high functional‐group tolerance and ample substrate scope, yielding fully substituted 1,2,3‐triazoles with complete positional site‐selectivity. The C?H selenylation could likewise be achieved by means of copper catalysis. Our findings highlight for the first time that weak O‐coordination can outcompete the strong N,N‐bidentate coordination mode in C?H functionalization technology.     

Hydroaminations of unactivated alkenes with basic alkylamines: group 4 metal halide catalysts and Brønsted-acid organocatalysts

Two distinct economical catalysts for intramolecular hydroaminations of electronically unactivated alkenes with basic amines are described, which are based on (a) group 4 metal halides under basic reaction conditions or (b) Br?nsted-acid organocatalysts.     

Novel strategies for the synthesis of anthrapyran antibiotics: discovery of a new antitumor agent and total synthesis of (S)-espicufolin

Two high-yielding strategies for the synthesis of 4H-anthra[1,2-b]pyran antibiotics have been developed giving access to novel antitumor agent (ED(50) 1.5 microm) and to (S)-espicufolin (3). A key step for the assembly of the tetracyclic 4H-anthra[1,2-b]pyran-4,7,12-trione skeleton is the nucleophilic addition of an aryl lithium species onto an aldehyde which allows the introduction of either an ynone or 1,3-diketo side chain, serving as precursors for an acid-catalysed cyclisation.     

NMR determination of smectic ordering of probe molecules

The NMR spectra of the three solutes ortho-, meta-, and para-dichlorobenzene in the nematic and smectic A phases of the liquid crystals 8CB and 8OCB are analyzed to yield two orientational order parameters for each solute. Extrapolation of the asymmetry in the energy parameters that describe the orientational ordering in the nematic phase are used to provide estimates of the strength of the nematic potential in the smectic A phase. The experimentally determined asymmetry of the orientational order parameters in the smectic A phase is then used in conjunction with Kobayashi-McMillan theory applied to solutes to give information about the smectic A layering and the nematic/smectic A coupling. In both smectic A solvents, the solute smectic coupling constant, tau, is negative (with the origin fixed at the center of the smectic layer) for all solutes. The signs and relative values of tau indicate that the ortho and para solutes favor the interlayer region while the meta solute is more evenly distributed throughout the layers.     

Trapping of the highly strained [5](2,4)quinolinophane system

The highly strained [5](2,4)quinolinophane system can be generated as an intermediate (2b), which is extremely susceptible towards the attack of both nucleophilic and electrophilic species. Addition of water at the carbon bridgehead C2 occurs rapidly and is followed by rearrangements to give a strain free product 10. An unusual carbene addition at the N1C2 bond of 2b is proposed to explain the formation of the strained ‘anti-Bredt’ type olefin 11.     

High-throughput simultaneous detection of point mutations and large-scale rearrangements by CE

The detection of unknown mutations is important both in population genetics research and in diagnosis. At present, two different methods must be used to detect either point mutations or large-scale genetic rearrangements, which is costly and time-consuming. We describe here a new method for the simultaneous detection of these two types of mutations. It is based on electrophoretic heteroduplex analysis (HDA) using enhanced mismatch mutation analysis (EMMA) and semiquantitative multiplexed PCR conditions. The use of such conditions allows the simultaneous search of any kind of mutation in up to five different fragments per capillary, in a single or multi-CE system. The method was validated on patient samples with mutations in the breast predisposition gene BRCA1. It leads to highly reliable and high-throughput mutation detection at low cost, as compared with classical methods.