Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Synthesis of 2-epi-amphidinolide E: an unexpected and highly selective C(2)inversion during an esterification reaction.

ABSTRACT: A synthesis of 2-epi-amphidinolide E (1) has been accomplished via an unexpected and highly diastereoselective C(2) stereochemical inversion during the modified Yamaguchi esterification of alcohol 4b and Fe(CO)3-complexed dienoic acid 7. [reaction: see text].

SUBMITTER: Va P

PROVIDER: S-EPMC2593877 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Synthesis of 2-epi-amphidinolide E: an unexpected and highly selective C(2)inversion during an esterification reaction.

Va Porino P Roush William R WR

Organic letters 20070101 2

A synthesis of 2-epi-amphidinolide E (1) has been accomplished via an unexpected and highly diastereoselective C(2) stereochemical inversion during the modified Yamaguchi esterification of alcohol 4b and Fe(CO)3-complexed dienoic acid 7. [reaction: see text]. ...[more]

PMID: 17217291

Similar Datasets

Total synthesis of amphidinolide E.

Project description:A convergent and highly stereocontrolled synthesis of amphidinolide E (1) has been accomplished. The synthesis features a highly diastereoselective (>20:1) BF3.Et2O promoted [3+2] annulation reaction between aldehyde 3 and allylsilane 4 to afford substituted tetrahydrofuran 2.

| S-EPMC2538580 | biostudies-literature

A formal synthesis of the C1-C9 fragment of amphidinolide C employing the Tamaru reaction.

Project description:Homoallylation of aldehydes with isoprene and triethylborane catalyzed by Ni(acac)(2) gave hydroxyalkenes in good yield with excellent regio- and stereoselectivity. Cross metathesis of the hydroxyalkenes with methyl acrylate using second-generation Grubbs catalyst and copper(I) iodide afforded alpha,beta-unsaturated esters, which underwent cyclization in the presence of DBU to produce tetrahydrofurans with the correct relative configuration for the C1-C9 fragment of amphidinolides C, C2, and F.

| S-EPMC2896498 | biostudies-literature

Highly selective synthesis of (E)-alkenyl-(pentafluorosulfanyl)benzenes through Horner-Wadsworth-Emmons reaction.

Project description:Diethyl 2-nitro-(pentafluorosulfanyl)benzylphosphonates, available by the vicarious nucleophilic substitution reaction of meta- and para-nitro-(pentafluorosulfanyl)benzenes and diethyl chloromethylphosphonate, undergo Horner-Wadsworth-Emmons reaction with aldehydes in the presence of potassium hydroxide in acetonitrile at ambient temperature to give (E)-2-nitro-1-alkenyl-(pentafluorosulfanyl)benzenes in good yields and high stereoselectivities. Follow-up transformations of the primary products provided (E)-1-alkenyl-(pentafluorosulfanyl)benzenes and 2-(2-arylethyl)-(pentafluorosulfanyl)anilines.

| S-EPMC3458736 | biostudies-literature

Selective Enzymatic Esterification of Lignin-Derived Phenolics for the Synthesis of Lipophilic Antioxidants.

Project description:Lignin is an abundant and renewable source of phenolic compounds that can be used as natural antioxidants to substitute synthetic, petroleum-based alternatives. The development of lignin depolymerization techniques has improved the accessibility of low-molecular-weight phenolic fractions with enhanced antioxidant activity compared to native lignin. The selective esterification of the aliphatic OH groups in these compounds is necessary in order to increase their compatibility with hydrophobic product matrixes, while preserving their antioxidant capacity. In the present work, lipase was chosen as a selective catalyst for the esterification of the monolignol dihydroconiferyl alcohol (DCA), in order to target the esterification of aliphatic OHs without modifying the aromatic groups. The reaction was studied under solvent-assisted and solvent-free conditions, using different fatty acids and substrate ratios. A product yield of 97% could be obtained after 24 h in a solvent-assisted reaction with 2 molar equivalents of fatty acid, or after 3 h in a solvent-free reaction with 10 molar equivalents of the fatty acid. The esterified monolignol showed relevant long-term radical scavenging activity, comparable to other commercial, petroleum-based antioxidants. Different lignin fractions were also used as substrates for enzymatic esterification with different fatty acids, resulting in esterification degrees of 20-58% (of the total aliphatic OH), depending on the specific combination of fatty acid-lignin fractions.

| S-EPMC10045519 | biostudies-literature

Studies for the total synthesis of amphidinolide P.

Project description:A convergent, enantiocontrolled total synthesis of the 15-membered macrolide, amphidinolide P, is described. The synthesis utilizes three nonracemic components for an efficient assembly of the macrolactone in 12 steps via the longest linear pathway. Key developments include studies of the Hosomi-Sakurai reaction for the formation of the C6-C7 bond, a "ligandless" palladium-mediated Stille cross-coupling of the vinylic stannane 4 and the alkenyl bromide 5 to produce a highly functionalized dienol, and a thermally induced, intramolecular lactonization via the late-stage formation of an intermediate ?-acylketene.

| S-EPMC3763838 | biostudies-literature

Selective Esterification of Phosphonic Acids.

Project description:Here, we report straightforward and selective synthetic procedures for mono- and diesterification of phosphonic acids. A series of alkoxy group donors were studied and triethyl orthoacetate was found to be the best reagent as well as a solvent for the performed transformations. An important temperature effect on the reaction course was discovered. Depending on the reaction temperature, mono- or diethyl esters of phosphonic acid were obtained exclusively with decent yields. The substrate scope of the proposed methodology was verified on aromatic as well as aliphatic phosphonic acids. The designed method can be successfully applied for small- and large-scale experiments without significant loss of selectivity or reaction yield. Several devoted experiments were performed to give insight into the reaction mechanism. At 30 °C, monoesters are formed via an intermediate (1,1-diethoxyethyl ester of phosphonic acid). At higher temperatures, similar intermediate forms give diesters or stable and detectable pyrophosphonates which were also consumed to give diesters. 31P NMR spectroscopy was used to assign the structure of pyrophosphonate as well as to monitor the reaction course. No need for additional reagents and good accessibility and straightforward purification are the important aspects of the developed protocols.

| S-EPMC8466293 | biostudies-literature

N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst.

Project description:N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature.

| S-EPMC3864184 | biostudies-literature

Optimized inversion-time schedules for quantitative T1 measurements based on high-resolution multi-inversion EPI.

Project description:PURPOSE:Demonstrate an optimized multi-inversion echo-planar imaging technique to accelerate quantitative T1 mapping by judicious selection of inversion times for each slice. METHODS:Slice ordering is optimized to maximize discrimination between tissues with different T1 values. The optimized slice orderings are tested in the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology phantom and compared with an unoptimized 21-measurement acquisition. The utility of the method is demonstrated in a healthy subject in vivo at 3?T and validated with a gold-standard inversion-recovery sequence. The in vivo precision of our technique was tested by repeated scans of the same subject within a scan session and across scan sessions, occurring 28 days apart. RESULTS:Phantom measurements yielded good agreement (R2 ?=?0.99) between the T1 estimates from the proposed optimized protocol, reference values from the National Institute of Standards and Technology phantom and gold-standard inversion-recovery values, as well as a negligible estimation bias that was slightly lower than that from the unoptimized 21-measurement protocol (0.74 versus 19 ms). The range of values for the scan-rescan coefficient of variation was 0.86 to 0.93 (within session) and 0.83 to 0.92 (across sessions) across all scan durations tested. CONCLUSIONS:Optimized slice orderings allow faster quantitative T1 mapping. The optimized sequence yielded accurate and precise T1 maps. Magn Reson Med 79:2101-2112, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

| S-EPMC5811323 | biostudies-literature

Amphidinolide B: total synthesis, structural investigation, and biological evaluation.

Project description:The total syntheses of amphidinolide B1 and the proposed structure of amphidinolide B2 have been accomplished. Key aspects of this work include the development of a practical, non-transition-metal-mediated method for the construction of the C13-C15 diene, the identification of ?-chelation and dipole minimization models for diastereoselective methyl ketone aldol reactions, the discovery of a spontaneous Horner-Wadsworth-Emmons macrocyclization strategy, and the development of a novel late stage method for construction of an allylic epoxide moiety. The originally proposed structure for amphidinolide B2 and diastereomers thereof display potent antitumor activities with IC50 values ranging from 3.3 to 94.5 nM against human solid and blood tumor cells. Of the different stereoisomers, the proposed structure of amphidinolide B2 is over 12-fold more potent than the C8,9-epimer and C18-epimer in human DU145 prostate cancer cells. These data suggest that the epoxide stereochemistry is a significant factor for anticancer activity.

| S-EPMC3631602 | biostudies-literature

Nitrosobenzene: Reagent for the Mitsunobu Esterification Reaction.

Project description:Nitrosobenzene has been demonstrated to participate in the Mitsunobu reaction in an analogous manner to dialkyl azodicarboxylates. The protocol using nitrosobenzene and triphenylphosphine (1:1) under mild conditions (0 °C) provides the ester derivatives of aliphatic and aromatic acids using various alcohols in moderate yield and with good enantioselectivity, giving the desired products predominantly with an inversion of configuration. The proposed mechanism, which is analogous to that observed using dialkyl azodicarboxylates, involves a nitrosobenzene-triphenylphosphine adduct and an alkoxytriphenylphosphonium ion and was supported by density functional theory calculations, 31P NMR spectroscopy, and experiments conducted with isotopically labeled substrates.

| S-EPMC6648318 | 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