Suthiweth T. Saengchantara

Bio: Suthiweth T. Saengchantara is an academic researcher from University of Salford. The author has contributed to research in topics: Chromone & Ring (chemistry). The author has an hindex of 8, co-authored 13 publications receiving 259 citations.

Advances in Quantum Mechanochemistry: Electronic Structure Methods and Force Analysis

Abstract: In quantum mechanochemistry, quantum chemical methods are used to describe molecules under the influence of an external force. The calculation of geometries, energies, transition states, reaction rates, and spectroscopic properties of molecules on the force-modified potential energy surfaces is the key to gain an in-depth understanding of mechanochemical processes at the molecular level. In this review, we present recent advances in the field of quantum mechanochemistry and introduce the quantum chemical methods used to calculate the properties of molecules under an external force. We place special emphasis on quantum chemical force analysis tools, which can be used to identify the mechanochemically relevant degrees of freedom in a deformed molecule, and spotlight selected applications of quantum mechanochemical methods to point out their synergistic relationship with experiments.

Inductive Heating with Magnetic Materials inside Flow Reactors

Abstract: Superparamagnetic nanoparticles coated with silica gel or alternatively steel beads are new fixed-bed materials for flow reactors that efficiently heat reaction mixtures in an inductive field under flow conditions. The scope and limitations of these novel heating materials are investigated in comparison with conventional and microwave heating. The results suggest that inductive heating can be compared to microwave heating with respect to rate acceleration. It is also demonstrated that a very large diversity of different reactions can be performed under flow conditions by using inductively heated flow reactors. These include transfer hydrogenations, heterocyclic condensations, pericyclic reactions, organometallic reactions, multicomponent reactions, reductive cyclizations, homogeneous and heterogeneous transition-metal catalysis. Silica-coated iron oxide nanoparticles are stable under many chemical conditions and the silica shell could be utilized for further functionalization with Pd nanoparticles, rendering catalytically active heatable iron oxide particles.

Ruthenium-NHC-catalyzed asymmetric hydrogenation of flavones and chromones: general access to enantiomerically enriched flavanones, flavanols, chromanones, and chromanols.

Abstract: Flavanoids and chromanoids including flavanones, flavanols, chromanones, and chromanols are a large family of well-known natural products (Scheme 1). 2] These natural products have been shown to exhibit a wide range of biological activities including anticancer, antitumor, antibacterial, antimicrobial, antioxidant, estrogenic, and antiestrogenic properties. Additionally, these chiral flavanoids and chromanoids could readily be utilized in the synthesis of many benzopyran-containing natural products by established reaction pathways (Scheme 1). Although there are numerous reports on the synthesis of flavanones, flavanols, chromanones, and chromanols, only few stereoselective methods have been devised to access enantiomerically enriched products. In fact, to the best of our knowledge, so far no transition-metal-catalyzed method has been reported for the highly enantioselective synthesis of 2-substituted flavanols and chromanols despite their importance. Owing to minimal negative environmental impact, high atom economy, and operational simplicity, the transition-metal-catalyzed asymmetric hydrogenation has long held a respected position both in academia and in industry for the preparation of optically active compounds. However, even though the enantioselective hydrogenation of natural and commercial chromones and flavones seems to be one of the most straightforward ways to synthesize flavanones, flavanols, chromanones, and chromanols, the asymmetric catalytic hydrogenation of chromones and flavones remains largely unexplored. It would be highly desirable to develop a general, efficient catalytic system for the asymmetric hydrogenation of these heterocycles. During the course of our investigation into the asymmetric hydrogenation of (hetero)arenes, we found that the combination of ruthenium(II) and several NHCs (NHC = N-heterocyclic carbene) led to the formation of highly active and enantioselective catalysts for the hydrogenation of quinoxalines, benzofurans, and (benzo)thiophenes. 10] In light of the high level of reactivity and enantioselectivity of our Ru–NHC catalyst, we rationalized that chromones and flavones could be hydrogenated directly to flavanols and chromanols in a stereoselective manner. Further we could easily obtain the enantiomerically enriched flavanones and chromanones by a simple and selective subsequent oxidation. Herein we report the first asymmetric hydrogenation of chromones and flavones using a chiral NHC–Ru complex. This direct and general route is capable of accessing biologically active enantiomerically enriched flavanoids and chromanoids comprising all the above-mentioned structures: flavanones, flavanols, chromanones, and chromanols (Scheme 2). Scheme 1. Representative structures of biologically active flavanoid and chromanoid natural products.