Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

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

ABSTRACT: 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.

SUBMITTER: Dupper NJ

PROVIDER: S-EPMC4482617 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

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

Dupper Nathan J NJ Kwon Ohyun O

Organic letters 20150211 4

Allylic alcohols can be transformed into γ,δ-unsaturated α,α-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 α,α-dibromo esters were subjected to various carbon-carbon bond-forming reactions, oxidations, and lactonizations. ...[more]

PMID: 25671693

Similar Datasets

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

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

Carbanion-accelerated Claisen rearrangements: asymmetric induction with chiral phosphorus-stabilized anions.

Project description:The carbanion-accelerated Claisen rearrangement has been extended to include phosphorus carbanion-stabilizing groups. The appropriately substituted allyl vinyl ethers are synthesized by the nucleophilic addition of allyl oxides to phosphorus-substituted allenes, which are obtained in one step from simple starting materials. The phosphorus-stabilized, carbanion-accelerated Claisen rearrangements proceed rapidly at room temperature in high yield, and the rearrangements are highly site- and stereoselective. The first examples of asymmetric induction in the Claisen rearrangement with chiral, phosphorus, anion-stabilizing groups are described. The observed asymmetric induction is highly dependent on the structure of the auxiliary and the metal counterion involved. Both internal and relative diastereoselectivity are high. A model for the observed sense of internal diastereoselectivity is proposed that is founded in the current understanding of the structure of phosphorus-stabilized anions.

| S-EPMC3537898 | biostudies-literature

Palladium-catalyzed gamma-arylation of alpha,beta-unsaturated esters from silyl ketene acetals.

Project description: Not available

| S-EPMC3159490 | biostudies-literature

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

Aestuaramides, a natural library of cyanobactin cyclic peptides resulting from isoprene-derived Claisen rearrangements.

Project description:We report 12 cyanobactin cyclic peptides, the aestuaramides, from the cultivated cyanobacterium Lyngbya aestuarii. We show that aestuaramides are synthesized enzymatically as reverse O-prenylated tyrosine ethers that subsequently undergo a Claisen rearrangement to produce forward C-prenylated tyrosine. These results reveal that a nonenzymatic Claisen rearrangement dictates isoprene regiochemistry in a natural system. They also reveal one of the mechanisms that organisms use to generate structurally diverse compound libraries starting from simple ribosomal peptide pathways (RiPPs).

| S-EPMC3657307 | biostudies-literature

Selective C-7 Functionalization of Phenanthridines by Microwave-Assisted Claisen Rearrangements of 8-Allyloxyphenanthridines.

Project description:Carbon-carbon bond formation in the phenanthridine 7-position was achieved by microwave-assisted Claisen rearrangement of 8-allyloxyphenanthridines. The reactions took place with excellent regioselectivity and high chemical yields. If the 7-position was substituted, rearrangement to C-9 took place, but the reaction occurred less readily. Rearrangements of 8-allyloxy-5,6-dihydrophenanthridines (phenanthridines with a saturated B-ring) gave a mixture of 7- and 9-substituted products. The experimental results were supported by DFT (density functional theory) calculations.

| S-EPMC10362114 | biostudies-literature

Highly functionalized 1,2-diamino compounds through reductive amination of amino acid-derived β-keto esters.

Project description:1,2-Diamine derivatives are valuable building blocks to heterocyclic compounds and important precursors of biologically relevant compounds. In this respect, amino acid-derived β-keto esters are a suitable starting point for the synthesis of β,γ-diamino ester derivatives through a two-step reductive amination procedure with either simple amines or α-amino esters. AcOH and NaBH(3)CN are the additive and reducing agents of choice. The stereoselectivity of the reaction is still an issue, due to the slow imine-enamine equilibria through which the reaction occurs, affording mixtures of diastereoisomers that can be chromatographically separated. Transformation of the β,γ-diamino esters into pyrrolidinone derivatives allows the configuration assignment of the linear compounds, and constitutes an example of their potential application in the generation of molecular diversity.

| S-EPMC3538761 | 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