Efficient Nitrate Conversion to Ammonia on f-Block Single-Atom/Metal Oxide Heterostructure via Local Electron-Deficiency Modulation

Exploring single-atom catalysts (SACs) for the nitrate reduction reaction (NO₃^-; NitRR) to value-added ammonia (NH₃) offers a sustainable alternative to both the Haber-Bosch process and NO₃^--rich wastewater treatment. However, due to the insufficient electron deficiency and unfavorable electronic structure of SACs, resulting in poor NO₃^--adsorption, sluggish proton (H*) transfer kinetics, and preferred hydrogen evolution, their NO₃^--to-NH₃ selectivity and yield rate are far from satisfactory. Herein, a systematic theoretical prediction reveals that the local electron deficiency of an f-block Gd single atom (Gd_SA) can be significantly regulated upon coordination with oxygen-defect-rich NiO (Gd_SA-D-NiO₄₀₀) support. Thus, facilitating stronger NO₃^- adsorption via strong Gd_5d-O_2p orbital coupling and further improving the protonation kinetics of adsorption intermediates by rapid H* capture from water dissociation catalyzed by the adjacent oxygen vacancy site along with suppressed H* dimerization synergistically boosts the NH₃ selectivity/yield rate. Motivated by DFT prediction, we delicately stabilized electron-deficient (strongly electrophilic) Gd_SA on D-NiO₄₀₀ (∼84% strong electrophilic sites), which exhibited excellent alkaline NitRR activity (NH₃ Faradaic efficiency ∼97% and yield rate ∼628 μg/(mg_cat h)) along with superior structural stability, as revealed by in situ Raman spectroscopy, significantly outperforming weakly electrophilic Gd nanoparticles, defect-free Gd_SA-P-NiO₄₀₀, and reported state-of-the-art catalysts.

Asymmetric Synthesis of Merck's Potent hNK1 Antagonist and Its Stereoisomers via Tandem Acylation/[3,3]-Rearrangement of 1,2-Oxazine N-Oxides

An asymmetric total synthesis of Merck's hNK₁ antagonist and three of its stereoisomers was accomplished in 10 steps. The synthesis involves a stereoselective assembly of 1,2-oxazine N-oxide by the [4 + 2]-cycloaddition, site-selective C-H oxygenation using a novel tandem acylation/[3,3]-rearrangement process and the reductive 1,2-oxazine ring contraction into a pyrrolidine ring as key stages. Using this strategy, the fused pyrrolidine subunit was constructed with exceptionally high regio- and stereoselectivities. The approach described here can be used to access enantiopure 3,4-disubstituted prolinols, which are frequently found in pharmaceutically relevant molecules and organocatalysts.

The Cyclic Nitronate Route to Pharmaceutical Molecules: Synthesis of GSK's Potent PDE4 Inhibitor as a Case Study

An efficient asymmetric synthesis of GlaxoSmithKline’s potent PDE4 inhibitor was accomplished in eight steps from a catechol-derived nitroalkene. The key intermediate (3-acyloxymethyl-substituted 1,2-oxazine) was prepared in a straightforward manner by tandem acylation/(3,3)-sigmatropic rearrangement of the corresponding 1,2-oxazine-N-oxide. The latter was assembled by a (4 + 2)-cycloaddition between the suitably substituted nitroalkene and vinyl ether. Facile acetal epimerization at the C-6 position in 1,2-oxazine ring was observed in the course of reduction with NaBH₃CN in AcOH. Density functional theory (DFT) calculations suggest that the epimerization may proceed through an unusual tricyclic oxazolo(1,2)oxazinium cation formed via double anchimeric assistance from a distant acyloxy group and the nitrogen atom of the 1,2-oxazine ring.

Nitro compounds as the core structures of promising energetic materials and versatile reagents for organic synthesis

This review addresses some promising areas of chemistry of nitro compounds extensively developed in recent years in Russia (particularly at the N.D.Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences) and worldwide. The most important results in the synthesis of novel energetic N-, C- and O-nitro compounds are summarized. New environmentally friendly approaches to the preparation of known compounds of this series, used as components of energetic compositions, are considered. Methods for selective transformations of various nitro compounds to valuable products of organic synthesis, primarily biologically active products and their precursors, are systematically analyzed.

The bibliography includes 446 references.

Zinc-catalyzed asymmetric nitrooxylation of β-keto esters/amides with a benziodoxole-derived nitrooxy transfer reagent

Zinc-catalyzed asymmetric nitrooxylation to afford a series of α-nitrooxy β-keto esters/amides in high yields and with low to moderate enantioselectivities has been disclosed.

Diastereoselective synthesis and profiling of bicyclic imidazolidinone derivatives bearing a difluoromethylated catechol unit as potent phosphodiesterase 4 inhibitors

Metal-mediated C–H functionalization of cyclic N-oxides was exploited to access new highly potent analogs of the phosphodiesterase 4 inhibitor Ro-20-1724.

Metal-Involving Synthesis and Reactions of Oximes

This review classifies and summarizes the past 10-15 years of advancements in the field of metal-involving (i.e., metal-mediated and metal-catalyzed) reactions of oximes. These reactions are diverse in nature and have been employed for syntheses of oxime-based metal complexes and cage-compounds, oxime functionalizations, and the preparation of new classes of organic species, in particular, a wide variety of heterocyclic systems spanning small 3-membered ring systems to macroheterocycles. This consideration gives a general outlook of reaction routes, mechanisms, and driving forces and underlines the potential of metal-involving conversions of oxime species for application in various fields of chemistry and draws attention to the emerging putative targets.