Browse
Submit Data
Databases
API
Help

Dataset Information

33 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Ring-opening carbonyl-olefin metathesis of norbornenes.

ABSTRACT: A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefin metathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscape for the full reaction pathway with six different hydrazines revealed several crucial aspects for the design of next-generation hydrazine catalysts. This study indicated that a [2.2.2]-bicyclic hydrazine should offer substantially increased reactivity versus the previously reported [2.2.1]-hydrazine due to a lowered activation barrier for the rate-determining cycloreversion step, a prediction which was verified experimentally. Optimized conditions for both cycloaddition and cycloreversion steps were identified, and a brief substrate scope study for each was conducted. A complication for catalysis was found to be the slow hydrolysis of the ring-opened hydrazonium intermediates, which were shown to suffer from a competitive and irreversible cycloaddition with a second equivalent of norbornene. This problem was overcome by the strategic incorporation of a bridgehead methyl group on the norbornene ring, leading to the first demonstrated catalytic carbonyl-olefin metathesis of norbornene rings.

SUBMITTER: Jermaks J

PROVIDER: S-EPMC8163149 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Ring-Opening Carbonyl-Olefin Metathesis of Cyclobutenes.

Project description:The ring-opening carbonyl-olefin metathesis of cyclobutenes to furnish γ,δ-unsaturated aldehydes-formal Claisen rearrangement products-is reported. The bistrifluoroacetic acid salt of 2,3-diazabicyclo[2.2.2]octane promotes these reactions efficiently with a variety of cyclobutenes and aldehydes, including aliphatic, α,β-unsaturated, aryl, and heteroaryl aldehydes. Catalytic reactions are also demonstrated.

| S-EPMC9555816 | biostudies-literature

GaCl<sub>3</sub>-Catalyzed Ring-Opening Carbonyl-Olefin Metathesis.

Project description:The development of a Lewis acid-catalyzed ring-opening cross-metathesis reaction which enables selective access to acyclic, unsaturated ketones as the carbonyl-olefin metathesis products is described. While catalytic amounts of FeCl3 were previously identified as optimal to catalyze ring-closing metathesis reactions, the complementary ring-opening metathesis between cyclic alkenes and carbonyl functionalities relies on GaCl3 as the superior Lewis acid catalyst.

| S-EPMC6905395 | biostudies-literature

Synthesis of 1,2-Dihydroquinolines via Hydrazine-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

Project description:The synthesis of 1,2-dihydroquinolines by the hydrazine-catalyzed ring-closing carbonyl-olefin metathesis (RCCOM) of N-prenylated 2-aminobenzaldehydes is reported. Substrates with a variety of substitution patterns are shown. With an acid-labile protecting group on the nitrogen atom, in situ deprotection and autoxidation furnish quinoline. In comparison with related oxygen-containing substrates, the cycloaddition step of the catalytic cycle is shown to be slower, but the cycloreversion is found to be more facile.

| S-EPMC7880559 | biostudies-literature

Ring-Opening Metathesis Polymerization and Related Olefin Metathesis Reactions in Benzotrifluoride as an Environmentally Advantageous Medium.

Project description:A tremendous number of solvents, either as liquids or vapors, contaminate the environment on a daily basis worldwide. Olefin metathesis, which has been widely used as high-yielding protocols for ring-opening metathesis polymerization (ROMP), ring-closing metathesis (RCM), and isomerization reactions, is typically performed in toxic and volatile solvents such as dichloromethane. In this study, the results of our systematic experiments with the Grubbs G1, G2, and Hoveyda-Grubbs HG2 catalysts proved that benzotrifluoride (BTF) can replace dichloromethane (DCM) in these reactions, providing high yields and similar or even higher reaction rates in certain cases. The ROMP of norbornene resulted not only in high yields but also in polynorbornenes with a high molecular weight at low catalyst loadings. Ring-closing metathesis (RCM) experiments proved that, with the exception of the G1 catalyst, RCM occurs with similar high efficiencies in BTF as in DCM. It was found that isomerization of (Z)-but-2-ene-1,4-diyl diacetate with the G2 and HG2 catalysts proceeds at significantly higher initial rates in BTF than in DCM, leading to rapid isomerization with high yields in a short time. Overall, BTF is a suitable solvent for olefin metathesis, such as polymer syntheses by ROMP and the ring-closing and isomerization reactions.

| S-EPMC9820898 | biostudies-literature

Catalytic, transannular carbonyl-olefin metathesis reactions.

Project description:Transannular carbonyl-olefin metathesis reactions complement existing procedures for related ring-closing, ring-opening, and intermolecular carbonyl-olefin metathesis. We herein report the development and mechanistic investigation of FeCl3-catalyzed transannular carbonyl-olefin metathesis reactions that proceed via a distinct reaction path compared to previously reported ring-closing and ring-opening protocols. Specifically, carbonyl-ene and carbonyl-olefin metathesis reaction pathways are competing under FeCl3-catalysis to ultimately favor metathesis as the thermodynamic product. Importantly, we show that distinct Lewis acid catalysts are able to distinguish between these pathways to enable the selective formation of either transannular carbonyl-ene or carbonyl-olefin metathesis products. These insights are expected to enable further advances in catalyst design to efficiently differentiate between these two competing reaction paths of carbonyl and olefin functionalities to further expand the synthetic generality of carbonyl-olefin metathesis.

| S-EPMC6979496 | biostudies-literature

Tropylium-promoted carbonyl-olefin metathesis reactions.

Project description:The carbonyl-olefin metathesis (COM) reaction is a highly valuable chemical transformation in a broad range of applications. However, its scope is much less explored compared to analogous olefin-olefin metathesis reactions. Herein we demonstrate the use of tropylium ion as a new effective organic Lewis acid catalyst for both intramolecular and intermolecular COM and new ring-opening metathesis reactions. This represents a significant improvement in substrate scope from recently reported developments in this field.

| S-EPMC6000984 | biostudies-literature

Synthesis of 2<i>H</i>-Chromenes via Hydrazine-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

Project description:The catalytic ring-closing carbonyl-olefin metathesis (RCCOM) of O-allyl salicylaldehydes to form 2H-chromenes is described. The method utilizes a [2.2.1]-bicyclic hydrazine catalyst and operates via a [3+2]/retro-[3+2] metathesis manifold. The nature of the allyl substitution pattern was found to be crucial, with sterically demanding groups such as adamantylidene or diethylidene offering optimal outcomes. A survey of substrate scope is shown along with a discussion of mechanism supported by DFT calculations. Steric pressure arising from syn-pentane minimization of the diethylidene moiety is proposed to facilitate cycloreversion.

| S-EPMC8172096 | biostudies-literature

Catalyst Behavior in Metal-Catalyzed Carbonyl-Olefin Metathesis.

Project description:Iron(III)-catalyzed carbonyl-olefin ring-closing metathesis employs reactivity not typically observed in Lewis acid-catalyzed reactions. In converting a ketone with a pendant olefin into a cycloalkene and a simple carbonyl byproduct, the reaction requires the Lewis acid catalyst to differentiate between the carbonyl of the substrate and that of the byproduct. It is necessary to determine how this solution interaction imparts the desired reactivity to best employ this method. Herein, we report detailed kinetic, spectroscopic, and colligative measurements applied toward the identification of the solution structures of the active Fe(III) and Ga(III) carbonyl-olefin metathesis catalysts. These data are consistent with formation of Lewis acid-carbonyl pairs for both metal systems under stoichiometric conditions. However, they diverge in the presence of higher equivalents of carbonyl, with Fe(III) forming highly ligated complexes, and no observed change for Ga(III). These findings are consistent with the resting state identity of the Fe(III) metathesis catalyst changing over the course of the reaction.

| S-EPMC7223925 | biostudies-literature

Interrupted carbonyl-olefin metathesis via oxygen atom transfer.

Project description:Some of the simplest and most powerful carbon-carbon bond forming strategies take advantage of readily accessible ubiquitous motifs: carbonyls and olefins. Here we report a fundamentally distinct mode of reactivity between carbonyls and olefins that differs from established acid-catalyzed carbonyl-ene, Prins, and carbonyl-olefin metathesis reaction paths. A range of epsilon, zeta-unsaturated ketones undergo Brønsted acid-catalyzed intramolecular cyclization to provide tetrahydrofluorene products via the formation of two new carbon-carbon bonds. Theoretical calculations and accompanying mechanistic studies suggest that this carbocyclization reaction proceeds through the intermediacy of a transient oxetane formed by oxygen atom transfer. The complex polycyclic frameworks in this product class appear as common substructures in organic materials, bioactive natural products, and recently developed pharmaceuticals.

| S-EPMC6983304 | biostudies-literature

Carbodiimide Ring-Opening Metathesis Polymerization

Project description:Controlled incorporation

| S-EPMC10311665 | biostudies-literature