Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Computational study of factors controlling the boat and chair transition states of Ireland-Claisen rearrangements.

ABSTRACT: The origins of the boat transition state preference in the Ireland-Claisen rearrangements studied experimentally by Kishi and co-workers have been explored computationally with Density Functional Theory. Steric interactions in the chair transition states were identified as the principal reason for the boat transition state preference.

SUBMITTER: Gul S

PROVIDER: S-EPMC2837782 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Computational study of factors controlling the boat and chair transition states of Ireland-Claisen rearrangements.

Gül Seref S Schoenebeck Franziska F Aviyente Viktorya V Houk K N KN

The Journal of organic chemistry 20100301 6

The origins of the boat transition state preference in the Ireland-Claisen rearrangements studied experimentally by Kishi and co-workers have been explored computationally with Density Functional Theory. Steric interactions in the chair transition states were identified as the principal reason for the boat transition state preference. ...[more]

PMID: 20166688

Similar Datasets

Synthesis of gamma,delta-unsaturated glycolic acids via sequenced brook and Ireland--claisen rearrangements.

Project description:Organozinc, -magnesium, and -lithium nucleophiles initiate a Brook/Ireland-Claisen rearrangement sequence of allylic silyl glyoxylates resulting in the formation of gamma,delta-unsaturated alpha-silyloxy acids.

| S-EPMC2830285 | biostudies-literature

Conjugate addition/Ireland-Claisen rearrangements of allyl fumarates: simple access to terminally differentiated succinates.

Project description:The conjugate addition of dialkylzinc reagents to allyl fumarates with subsequent Ireland-Claisen rearrangement has been accomplished yielding substituted unsymmetrical succinic acid derivatives. This one-pot reaction creates two new carbon-carbon bonds at contiguous stereogenic centers. The reaction proceeds for several alkylzinc reagents and substituted allyl fumarates. The products contain distinguishable functional handles for further manipulation.

| S-EPMC2822989 | biostudies-literature

Are boat transition states likely to occur in Cope rearrangements? A DFT study of the biogenesis of germacranes.

Project description:It has been proposed that elemanes are biogenetically formed from germacranes by Cope sigmatropic rearrangements. Normally, this reaction proceeds through a transition state with a chair conformation. However, the transformation of schkuhriolide (germacrane) into elemanschkuhriolide (elemane) may occur through a boat transition state due to the final configuration of the elemanschkuhriolide, but this transition state is questionable due to its high energy. The possible mechanisms of this transformation were studied in the density functional theory frame. The mechanistic differences between the transformation of (Z,E)-germacranes and (E,E)-germacranes were also studied. We found that (Z,E)-germacranolides are significantly more stable than (E,E)-germacranolides and elemanolides. In the specific case of schkuhriolide, even when the boat transition state is not energetically favored, a previous hemiacetalization lowers enough the energetic barrier to allow the formation of a very stable elemanolide that is even more stable than its (Z,E)-germacrane.

| S-EPMC5629395 | biostudies-literature

Aromatic Claisen Rearrangements of O-prenylated tyrosine and model prenyl aryl ethers: Computational study of the role of water on acceleration of Claisen rearrangements.

Project description:LynF, an enzyme from the TruF family, O-prenylates tyrosines in proteins; subsequent Claisen rearrangements give C-prenylated tyrosine products. These reactions in tyrosines and model phenolic systems have been explored with DFT and SCS-MP2 calculations. Various ab initio benchmarks have been computed (CBS-QB3, MP2, SCS-MP2) to examine the accuracy of commonly used density functionals, such as B3LYP and M06-2X. Solvent effects from water were considered using implicit and explicit models. Studies of the ortho-C-prenylation and Claisen rearrangement of tyrosine, and the Claisen rearrangement of α,α-dimethylallyl (prenyl) coumaryl ether establish the energetics of these reactions in the gas phase and in aqueous solution.

| S-EPMC3873100 | biostudies-literature

Toward the Synthesis of Antascomicin B. Synthesis of a Model of the C22-C34 Fragment via Ireland-Claisen and Allylic Diazene Rearrangements.

Project description:The C22-C34 fragment of antascomicin B lacking the C31 and C32 hydroxyl groups has been prepared in 11 steps from commercially available 2-OH-cyclohexanone. An Ireland-Claisen rearrangement was employed to install the C26 and C27 stereocenters. Our recently reported diastereoselective acyclic 1,3-reductive transposition was used to establish the remote C23 stereocenter. Directed hydrogenation was employed to set the C29 stereocenter. The model compound contains 5 of the stereocenters and all of the carbons of the corresponding fragment of antascomicin B.

| S-EPMC2614681 | biostudies-literature

Capturing transition paths and transition states for conformational rearrangements in the ribosome.

Project description:To reveal the molecular determinants of biological function, one seeks to characterize the interactions that are formed in conformational and chemical transition states. In other words, what interactions govern the molecule's energy landscape? To accomplish this, it is necessary to determine which degrees of freedom can unambiguously identify each transition state. Here, we perform simulations of large-scale aminoacyl-transfer RNA (aa-tRNA) rearrangements during accommodation on the ribosome and project the dynamics along experimentally accessible atomic distances. From this analysis, we obtain evidence for which coordinates capture the correct number of barrier-crossing events and accurately indicate when the aa-tRNA is on a transition path. Although a commonly used coordinate in single-molecule experiments performs poorly, this study implicates alternative coordinates along which rearrangements are accurately described as diffusive movements across a one-dimensional free-energy profile. From this, we provide the theoretical foundation required for single-molecule techniques to uncover the energy landscape governing aa-tRNA selection by the ribosome.

| S-EPMC4269782 | biostudies-literature

Functionalized ?,?-dibromo esters through Claisen rearrangements of dibromoketene acetals.

Project description:Allylic alcohols can be transformed into ?,?-unsaturated ?,?-dibromo esters through a two-step process: formation of a bromal-derived mixed acetal, followed by tandem dehydrobromination/Claisen rearrangement. The scope and selectivity of both steps have been investigated. The product ?,?-dibromo esters were subjected to various carbon-carbon bond-forming reactions, oxidations, and lactonizations.

| S-EPMC4482617 | biostudies-literature

Enantioselective Claisen rearrangements with a hydrogen-bond donor catalyst.

Project description:N,N'-Diphenylguanidinium ion associated with the noncoordinating BArF counterion is shown to be an effective catalyst for the [3,3]-sigmatropic rearrangement of a variety of substituted allyl vinyl ethers. Highly enantioselective catalytic Claisen rearrangements of ester-substituted allyl vinyl ethers are then documented using a new C2-symmetric guanidinium ion derivative.

| S-EPMC2547484 | biostudies-literature

Structure-reactivity relationships of zwitterionic 1,3-diaza-Claisen rearrangements.

Project description:Bridged bicyclic tertiary allylic amines aza-norbornene 1 and isoquinuclidene 2 add to isocyanates, isothiocyanates, and in situ-generated carbodiimides to form zwitterionic intermediates that undergo 1,3-diaza-Claisen rearrangements to afford highly substituted ureas, thioureas, and guanidines, respectively. Aza-norbornene 1 is significantly more reactive toward 1,3-diaza-Claisen rearrangements than isoquinuclidene 2. This reactivity difference is most likely due to the inherent ring strain in the aza-bicyclo[2.2.1]heptene ring system of aza-norbornene 1. The most apparent reactivity trend of the heterocumulenes is that the most electron-deficient heterocumulenes are more reactive toward 1,3-diaza-Claisen rearrangements. The introduction of a new stereocenter α- to the nucleophilic nitrogen in aza-norbornene 1 and isoquinuclidine 2 decreases the reactivity toward 1,3-diaza-Claisen rearrangements, while the exodiastereomers 3b and 4b are less reactive than the corresponding endodiastereomers 3a and 4a. Isocyanates that bear an electron-withdrawing group react with allylic amines 1-3b to afford mixtures of ureas and isoureas; however, with excess isocyanate and heat, thermodynamic equilibration is possible affording ureas. Inspired by this observation, a one-pot reaction of isocyanates with amines 1, 2, and 3b followed by BF3·OEt2-catalyzed isomerization of the urea/isourea mixture was developed that affords the corresponding ureas in excellent yields.

| S-EPMC4356197 | biostudies-literature

Stereoselective synthesis of quaternary carbons via the dianionic Ireland-Claisen rearrangement.

Project description:A dianionic Ireland-Claisen rearrangement of chiral, nonracemic ?-methyl-?-hydroxy allylic esters has been developed that proceeds with high diastereoselectivity and provides products containing three contiguous stereogenic carbons, including a quaternary center. The potential utility of the rearrangement for complex molecule synthesis is also demonstrated.

| S-EPMC4018138 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data