Air Family Research Articles

Investigation of NNN Pincer Ruthenium(II) Complexes with a Pendant Hydroxyl Group for N‐Monomethylation of amines and Nitroarenes by Methanol

AbstractA family of air‐ and moisture‐stable NNN pincer ruthenium(II) complexes with a pendant OH were developed, which exhibit unprecedented high reactivity and selectivity in N‐monomethylation of amines and nitroarenes using methanol. The investigation reveals adopting the combination of 1H‐pyrazole‐1‐yl and 3,5‐dimethyl‐4‐hydroxyethyl‐1H‐pyrazol‐1‐yl as the two assistant arms of the pyridyl‐backbone is a suitable choice. The mechanism study discloses that, during the catalytic cycle, dehydrogenation of methanol to form formaldehyde is a fast and reversible step.

Benzimidazolyl Palladium Complexes as Highly Active and General Bifunctional Catalysts in Sustainable Cross-Coupling Reactions

A family of air- and moisture-stable dinuclear palladium complexes bearing 2-benzimidazolyl ligands is reported and shown to be a highly effective and general catalytic platform in diverse cross-coupling reactions. The rigidity and conformation of the ligand scaffold was readily modified via tethering of the 2-benzimidazolyl moiety to diamine ligands, resulting in significant changes in catalytic activity. Under optimal conditions, Suzuki, Heck, and Sonogashira-type couplings of aryl bromides can all be performed efficiently with good functional group compatibility using only 0.1 mol % of catalyst, in aqueous or alcohol solvents. Experimental evidence highlights the importance of the bifunctional character of the ligand for catalytic activity, where the basic N-functionality in the ligand framework is proposed to accelerate (trans)metalation steps via intramolecular assistance.

항공사고 피해자 가족지원 제도개선 연구

항공사고 피해자 가족지원 제도개선 연구

Palladacyclic Imidazoline–Naphthalene Complexes: Synthesis and Catalytic Performance in Pd(II)-Catalyzed Enantioselective Reactions of Allylic Trichloroacetimidates

A new family of air- and moisture-stable enantiopure C,N-palladacycles (PIN-acac complexes) were prepared in good overall yield in three steps from 2-iodo-1-naphthoic acid and enantiopure β-amino alcohols. Three of these PIN complexes were characterized by single-crystal X-ray analysis. As anticipated, the naphthalene and imidazoline rings of PIN-acac complexes 18a and 18b were canted significantly from planarity and projected the imidazoline substituents R(1) and R(2) on opposite faces of the palladium square plane. Fifteen PIN complexes were evaluated as catalysts for the rearrangement of prochiral (E)-allylic trichloroacetimidate 19 (eq 2) and the S(N)2' allylic substitution of acetic acid with prochiral (Z)-allylic trichloroacetimidate 23. Although these complexes were kinetically poor catalysts for the Overman rearrangement, they were good catalysts for the allylic substitution reaction, providing branched allylic esters in high yield. However, enantioselectivities were low to moderate and significantly less than that realized with palladacyclic complexes of the COP family. Computational studies support an anti-acetoxypalladation/syn-deoxypalladation mechanism analogous to that observed with COP catalysts. The computational study further suggests that optimizing steric influence in the vicinity of the carbon ligand of a chiral C,N-palladacycle, rather than near the nitrogen heterocycle, is the direction to pursue in future development of improved enantioselective catalysts of this motif.

Total synthesis and study of myrmicarin alkaloids

The myrmicarins are a family of air- and temperature-sensitive alkaloids that possess unique structural features. Our concise enantioselective synthesis of the tricyclic myrmicarins enabled evaluation of a potentially biomimetic assembly of the complex members via direct dimerization of simpler structures. These studies revealed that myrmicarin 215B undergoes efficient and highly diastereoselective Brønsted acid-induced dimerization to generate a new heptacyclic structure, isomyrmicarin 430A. Mechanistic analysis demonstrated that heterodimerization between myrmicarin 215B and a conformationally restricted azafulvenium ion precursor afforded a functionalized isomyrmicarin 430A structure in a manner that was consistent with a highly efficient, non-concerted ionic process. Recent advancement in heterodimerization between tricyclic derivatives has enabled the preparation of strategically functionalized hexacyclic structures. The design and synthesis of structurally versatile dimeric compounds has greatly facilitated manipulation of these structures en route to more complex myrmicarin derivatives.

Readily Available Phosphine−Phosphoramidite Ligands for Highly Efficient Rh-Catalyzed Enantioselective Hydrogenations

A new family of air- and moisture-stable phosphine-phosphoramidite ligands (PEAPhos) has been prepared from commercially available and inexpensive (S)-alpha-phenylethylamine through a two- or three-step transformation and successfully applied in the rhodium-catalyzed enantioselective hydrogenations of a variety of substrates, in which up to 99.9% ee was obtained for all of these kinds of substrates.

Study of Multiple Meson Production at Cosmic Ray Energy. III: Transverse Behaviour of Gamma-Ray Air Family

Study of Multiple Meson Production at Cosmic Ray Energy. III: Transverse Behaviour of Gamma-Ray Air Family

Study of Multiple Meson Production at Cosmic Ray Energy. II: Analytical Derivation of Lateral Structure Function of Gamma-Ray Air Family

Study of Multiple Meson Production at Cosmic Ray Energy. II: Analytical Derivation of Lateral Structure Function of Gamma-Ray Air Family

Study of Multiple Meson Production at Cosmic Ray Energy. I: Longitudinal Behaviour of Gamma Ray Air Family

Study of Multiple Meson Production at Cosmic Ray Energy. I: Longitudinal Behaviour of Gamma Ray Air Family