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2‐Hydroxypyridines have emerged as versatile nucleophiles in organic synthesis. The N‐ and O‐functionalization of 2‐hydroxypyridines affords straightforward and practical methods for the construction of N‐substituted 2‐pyridones and O‐substituted 2‐hydroxypyridines, which are important structural motifs in numerous natural products, pharmaceuticals and biologically active compounds. Nonetheless, the competition between N‐ and O‐functionalization of 2‐hydroxypyridines presents an inevitable and formidable challenge. In the past few decades, chemoselective N‐ and/or O‐functionalization of 2‐hydroxypyridines has received extensive attention from the synthetic community, resulting in the development of elegant and effective strategies to address this chemoselectivity. This review provides a summary of recent advancements in the realm of transition‐metal and organo‐catalyzed, as well as visible‐light promoted chemoselective functionalization of 2‐hydroxypyridines, including N‐alkylation, N‐allylation, N‐arylation, N‐alkenylation, O‐alkylation, O‐allylation, O‐arylation, and O‐alkenylation. [ABSTRACT FROM AUTHOR]

Marine dinoflagellates produce remarkable organic molecules, particularly those with polyoxygenated long-carbon- chain backbones, namely super-carbon-chain compounds (SCCCs), characterized by the presence of numerous stereogenic carbon centers on acyclic polyol carbon chains. Even today, it is a challenge to determine the absolute configurations of these compounds. In this work, the planar structures and absolute configurations of two highly flexible SCCCs, featuring either a C69- or C71-linear carbon backbone, gibbosols A and B, respectively, each containing thirty-seven stereogenic carbon centers, were unambiguously established by a combined chemical, spectroscopic, and computational approach. The discovery of gibbosols A and B with two hydrophilic acyclic polyol chains represents an unprecedented class of SCCCs. A reasonable convergent strategy for the biosynthesis of these SCCCs was proposed. [ABSTRACT FROM AUTHOR]

The morphology and interfacial structure of the ε'-Mg54Ag17 precipitates in a peak-aged Mg-Sn-Mn-Ag-Zn alloy have been investigated using transmission electron microscopy. A typical ε'-Mg54Ag17 precipitate exhibits a (0001)α habit plane and three pairs of side facets, with two major pairs of facets being in irrational orientations. The orientation of each preferred interface is normal to a vector connecting two adjacent diffraction spots from different phases (Δg). Using the constrained coincidence site lattice (CCSL) model, the interface orientations have been interpreted according to the degree of matching on the interfaces. The detailed stepped structures in the irrational facets and dislocation configurations in the side facets have been predicted using the secondary CCSL (II-CCSL) and the secondary O-lattice model. Both the calculated terrace/ledge and dislocation configurations in side facets are in good agreement with the high-resolution transmission microscopy observations. [ABSTRACT FROM AUTHOR]

A facile method for the stereoselective synthesis of trans-2,3-dihydrobenzofurans from ortho-quinone methides in situ generated from readily available 2-alkyl-substituted phenols using silver oxide-mediated oxidation has been developed. Additionally, the 2,3-dihydrobenzofurans can be further transformed into the aromatized 2,3-disubstituted benzofurans in the presence of DDQ. [ABSTRACT FROM AUTHOR]

Hi, neighbor! The first organocatalyzed asymmetric transfer hydrogenation of aromatic nitro compounds was successfully developed with up to 99 % ee. The new methodology provides a direct and facile access to enantiopure cyclic nitro compounds with two contiguous stereocenters. [ABSTRACT FROM AUTHOR]

Asymmetrische Hydrierung: Die Titelreaktion bietet einen schnellen Zugang zu chiralen 1 ‐ und 3 ‐ substituierten 1,2,3,4 ‐ Tetrahydroisochinolinen mit exzellenter Enantioselektivität (siehe Schema; L=Ligand). Mechanistische Studien ergeben, dass die 1,2 ‐ Hydrid ‐ Addition der einleitende Schritt der Reaktion sein könnte. Die Methode wurde in der Synthese des krampflösenden Wirkstoffs (+) ‐ Solifenacin genutzt. [ABSTRACT FROM AUTHOR]

To increase HF-GWR portability, it is very desirable to use smaller antennas yet achieve higher angular resolving power. Based on the MUSIC algorithm, the angular resolving powers of various combined cross-loop/monopole and monopole antenna arrays are studied with variations of target angles, signal-to-noise ratio, and sampling density. It is found that a combination of two cross-loop/monopole antennas plus one monopole antenna gives the best performance. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 171–175, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11160 [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Enantioselective Synthesis of Trifluoromethyl Substituted Piperidines with Multiple Stereogenic Centers via Hydrogenation of Pyridinium Hydrochlorides" by M.-W. Chen, published in the periodical "Organic Chemistry Frontiers" in 2015.

Review: [30 refs.+ subrefs.] [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Enantioselective Synthesis of Endocyclic β-Amino Acids with Two Contiguous Stereocenters via Hydrogenation of 3-Alkoxycarbonyl-2-Substituted Quinolines" by Z.-S. Ye et al. published in the journal "Synthesis" in the 2013 issue.

A C3-TunePhos is used as ligand in the title reaction to produce chiral products which represent subunits of pharmaceuticals. [ABSTRACT FROM AUTHOR]

Review: 49 refs. [ABSTRACT FROM AUTHOR]

Key feature in the preparation of chiral piperidines is the activation of simple pyridines as N-benzyl-pyridinium bromides. [ABSTRACT FROM AUTHOR]

An efficient method for the enantioselective hydrogenation of 3,4-disubstituted isoquinolines is developed. [ABSTRACT FROM AUTHOR]