Effects on Rotational Dynamics of Azo and Hydrazodicarboxamide-Based Rotaxanes

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This manuscript version is made available under the CC-BY 4.0 license https://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Molecules. To access the final edited and published work see https://doi.org/10.3390/molecules22071078The synthesis of novel hydrogen-bonded [2]rotaxanes having two pyridine rings in the macrocycle and azo- and hydrazodicarboxamide-based templates decorated with four cyclohexyl groups is described. The different affinity of the binding sites for the benzylic amide macrocycle and the formation of programmed non-covalent interactions between the interlocked components have an important effect on the dynamic behavior of these compounds. Having this in mind, the chemical interconversion between the azo and hydrazo forms of the [2]rotaxane was investigated to provide a chemically-driven interlocked system enable to switch its circumrotation rate as a function of the oxidation level of the binding site. Different structural modifications were carried out to further functionalize the nitrogen of the pyridine rings, including oxidation, alkylation or protonation reactions, affording interlocked azo-derivatives whose rotation dynamics were also analyzed

Mechanically interlocked molecules in metal–organic frameworks

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Chemical Society Reviews, copyright © Royal Society of Chemistry after peer review and technical editing by the publisher. To access the final edited and published work see: https://pubs.rsc.org/en/content/articlelanding/2022/CS/D2CS00167EMechanically interlocked molecules (MIMs) have great potential in the development of molecular machinery due to their intercomponent dynamics. The incorporation of these molecules in a condensed phase makes it possible to take advantage of the control of the motion of the components at the macroscopic level. Metal–organic frameworks (MOFs) are postulated as ideal supports for intertwined molecules. This review covers the chemistry of the mechanical bond incorporated into metal–organic frameworks from the seminal studies to the latest published advances. We first describe some fundamental concepts of MIMs and MOFs. Next, we summarize the advances in the incorporation of rotaxanes and catenanes inside MOF matrices. Finally, we conclude by showing the study of the rotaxane dynamics in MOFs and the operation of some stimuli-responsive MIMs within MOFs. In addition to emphasising some selected examples, we offer a critical opinion on the state of the art of this research field, remarking the key points on which the future of these systems should be focused

Ring-to-Thread Chirality Transfer in [2]Rotaxanes for the Synthesis of Enantioenriched Lactams

© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. This manuscript version is made available under the CC-BY-NC 4.0 license https://creativecommons.org/licenses/by-nc/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Angewandte Chemie International Edition. To access the final edited and published work see https://doi.org/10.1002/anie.202209904The synthesis of chiral mechanically interlocked molecules has attracted a lot of attention in the last few years, with applications in different fields, such as asymmetric catalysis or sensing. Herein we describe the synthesis of orientational mechanostereoisomers, which include a benzylic amide macrocycle with a stereogenic center, and nonsymmetric N-(arylmethyl)fumaramides as the axis. The base-promoted cyclization of the initial fumaramide thread allows enantioenriched value-added compounds, such as lactams of different ring sizes and amino acids, to be obtained. The chiral information is effectively transmitted across the mechanical bond from the encircling ring to the interlocked lactam. High levels of enantioselectivity and full control of the regioselectivity of the final cyclic compounds are attained

Heterociclos en sínteses orgánica : introconversión de grupos funcionales, síntesis de triazolopiridinas y compuestos meso-iónicos / Mateo Alajarín Cerón ; Director Pedro Molina buendia.

Tesis - Universidad de Murcia.Consulte la tesis en: BCA. GENERAL. ARCHIVO UNIVERSITARIO. TM 3262

The Elusive 1,4-Diazabutatrienes: Lurking in the Shadows

Isocyanides are isomers of cyanides in which its terminal carbon atom can exist in a divalent state. Their ambivalent electronic nature as nucleophile or electrophile and wide reactivity turn the isocyanide scaffold in a valuable synthon for the synthesis of structurally complex molecules, in particular azacycles. Although they are known to polymerize easily, the dimerization of isocyanides affording head-to-head dimers, namely 1,4-diazabutatrienes R1-N=C=C=N-R1, has been scarcely explored. Nowadays the experimental isolation of this kind of heterocumulenes is still a challenge. In this minireview, covering a period of sixty years, we highlight the role of 1,4-diazabutatienes as putative reaction intermediates in the homo- and heterodimerization of different types of isocyanides. Added to this, we revise a set of reported reactions in which the formation of a transient 1,4-diazabutatriene intermediate has not been proposed but could be considered as a plausible alternative

Enantioselective Formation of 2-Azetidinones by Ring-Assisted Cyclization of Interlocked N-(alpha-Methyl)benzyl Fumaramides

The synthesis of optically active interlocked and non-interlocked 2-azetidinones by intramolecular cyclization of N-(alpha-methyl)benzyl fumaramide [2]rotaxanes is described. Two different strategies of asymmetric induction were tested in which the chiral group was located either proximal or distal to the reacting center of the thread. During these experiments, an interesting equilibration process inside the macrocyclic void occurred, thus leading to the cyclization through the (alpha-methyl)benzyl carbon atom and giving rise to beta-lactams, with a quaternary carbon atom, in an enantio- and diastereocontrolled manner. This cyclization also proceeds in kinetically stable chiral pseudo[2]rotaxanes, thus allowing further de threading to provide enantioenriched 3,4-disubstituted trans-2-azetidinones. The stereochemical outcomes of the cyclization inside and outside the macrocycle demonstrated noticeabl

Enantioselective Formation of 2‐Azetidinones by Ring‐Assisted Cyclization of Interlocked N

The synthesis of optically active interlocked and non-interlocked 2-azetidinones by intramolecular cyclization of N-(alpha-methyl)benzyl fumaramide [2]rotaxanes is described. Two different strategies of asymmetric induction were tested in which the chiral group was located either proximal or distal to the reacting center of the thread. During these experiments, an interesting equilibration process inside the macrocyclic void occurred, thus leading to the cyclization through the (alpha-methyl)benzyl carbon atom and giving rise to beta-lactams, with a quaternary carbon atom, in an enantio- and diastereocontrolled manner. This cyclization also proceeds in kinetically stable chiral pseudo[2]rotaxanes, thus allowing further de threading to provide enantioenriched 3,4-disubstituted trans-2-azetidinones. The stereochemical outcomes of the cyclization inside and outside the macrocycle demonstrated noticeabl

Redox divergent conversion of a [2]rotaxane into two distinct degenerate partners with different shuttling dynamics

The submolecular translational movement in novel hydrogen-bonded [2]rotaxanes containing benzylic amide macrocycles and two azo/hydrazodicarboxamide binding sites was analyzed by dynamic NMR spectroscopy. The results show that the activation free energies of the macrocycle shuttling in these systems depend on the oxidation level of both nitrogen-based binding sites embedded in the thread; the shuttling motion being more rapid in [2]rotaxanes at the lower oxidation level bis(hydrazo)-based rotaxanes. Moreover, by means of a fully controllable chemical switching, these two-station [2]rotaxanes are able to swap over three different dynamic states, which differ in macrocycle shuttling velocity: a) faster in a bis(hydrazo) [2]rotaxane, the lower oxidation state; b) moderate in a bis(azo) [2]rotaxane, the higher oxidation state; and c) practically stopped at the azodicarboxamide station of an azo/hydrazo [2]rotaxane, the intermediate oxidation state. Thus, from this latter resting state, two “fans” of different velocity can be turned on and off by simple chemical redox processes

Chemodivergent Conversion of Ketenimines Bearing Cyclic Dithioacetalic Units into Isoquinoline-1-thiones or Quinolin-4-ones as a Function of the Acetalic Ring Size

C-Alkoxycarbonyl-C-phenyl-N-aryl ketenimines bearing 1,3-dithiolan-2-yl or 1,3-dithian-2-yl substituents at ortho position of the C-phenyl ring, respectively, transform into isoquino-line-1-thiones and quinolin-4-ones under thermal treatment in toluene solution. The formation of isoquinolinethiones involves a rare degradation of the 1,3-dithiolane ring, whereas, in contrast, the 1,3-dithiane ring remains intact during the reaction course leading to quinolin-4-ones. Computational density functional theory results support that the kinetically favorable mechanism for the formation of isoquinoline-l-thiones proceeds through a [1,5]-hydride shift/6 pi-electrocyclization cascade, followed by a thiirane extrusion process. Alternative mechanistic paths showing interesting electronic reorganization processes have been also scrutinized but resulted not competitive on energetic grounds