Dipyridine N,N′-dioxide is a structural fragment found in many bioactive compounds. Furthermore, chiral analogues secured their place as powerful Lewis base catalysts. Scope of the existing methods for the synthesis of atropisomeric dipyridine N,N′-dioxides is limited. Herein, we present a practical, highly chemo-and stereoselective method for oxidative dimerization of chiral pyridine N-oxides using O2 as a terminal oxidant. A series of 13 axially chiral dipyridine N,N′-dioxides were synthesized in up to 75% yield.

The design of catalysts for asymmetric propargylations remains a challenging task, with only a handful of methods providing access to enantioenriched homopropargylic alcohols. In this work, guided by previously reported computational predictions, a set of atropisomeric bipyridine N,N'-dioxides was tested as Lewis base catalysts for the asymmetric propargylation of aldehydes with trichloroallenylsilane. The catalysts are easily prepared in four simple steps starting from readily available methyl ketones. Aryl-substituted derivatives proved to be highly active and showed a high level of enantiocontrol even at 1 mol% loading. The reaction scope includes a wide range of aromatic, heteroaromatic, and unsaturated aldehydes. New computations confirm that the key stereodetermining transition state structures for the synthesized catalysts are similar to those previously reported for the model structure.

Deoxygenation of heteroaromatic N‐oxides is commonly accomplished using chemical or enzymatic methods. In this work, we report on an expedient protocol for electrochemical reduction of pyridine N‐oxide derivatives under mild conditions. A diverse range of mono‐ and bis N‐oxides were converted into the corresponding nitrogen bases in good yields. Importantly, the method is highly selective towards N‐oxides and tolerates challenging halo and nitro substituents in the heteroaromatic ring.

Calcium alginate beads covalently linked with -cyclodextrin (-CD-alginate beads) were prepared and examined for their ability to serve as a supporting matrix for bacterial degradation of nonylphenol, an endocrine disruptor. Column chromatographic experiment using -CD-alginate beads with diameter of 657 ± 82 m and with degree of CD substitution of 0.16 showed a strong affinity for nonylphenol adsorption. Although addition of -CD (2.7-27 mM) to the culture broth of Sphingomonas cloacae retarded nonylphenol degradation, the immobilized bacteria on the CD-alginate beads were effective for the degradation. Batch degradation tests using the immobilized bacteria on -CD-alginate-beads showed 46% nonylphenol recovery after 10-day incubation at 25 ± 2 °C, and the recovery reached to about 17% when wide and shallow incubation tubes were used to facilitate uptake of the viscous liquid of nonylphenol on the surface of the medium. Scanning electron microscopic photographs revealed that multiplicated bacteria was present both on the surface and inside the beads and the matrix of CD-alginate was stable and suitable during 10-day incubation.

A simple and efficient method to remove hydrophobic phenolic pollutants from aqueous solutions has been investigated using the inclusion ability and cationic property of mono(6-amino-6-deoxy)-α-cyclodextrin (ACD) and a cation exchanger. The inclusion complexes of nonylphenol and bisphenol A with ACD were almost completely adsorbed onto a column of a cation exchanger and desorbed with diluted aqueous ammonia solution. Moreover, bisphenol A was also adsorbed on a column of the cation exchanger that was pretreated with ACD.