Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Total synthesis of (±)-hirsutine: application of phosphine-catalyzed imine-allene [4 + 2] annulation.

ABSTRACT: The total synthesis of the indole alkaloid hirsutine has been achieved, with a key step being the application of our phosphine-catalyzed [4 + 2] annulation of an imine with ethyl ?-methylallenoate. From commercially available indole-2-carboxaldehyde, the target was synthesized in 14 steps and 6.7% overall yield.

SUBMITTER: Villa RA

PROVIDER: S-EPMC3439149 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Total synthesis of (±)-hirsutine: application of phosphine-catalyzed imine-allene [4 + 2] annulation.

Villa Reymundo A RA Xu Qihai Q Kwon Ohyun O

Organic letters 20120824 17

The total synthesis of the indole alkaloid hirsutine has been achieved, with a key step being the application of our phosphine-catalyzed [4 + 2] annulation of an imine with ethyl α-methylallenoate. From commercially available indole-2-carboxaldehyde, the target was synthesized in 14 steps and 6.7% overall yield. ...[more]

PMID: 22920858

Similar Datasets

Enantioselective total synthesis of (+)-ibophyllidine via an asymmetric phosphine-catalyzed [3 + 2] annulation.

Project description:In this study we performed the total synthesis of the terpene indole alkaloid (+)-ibophyllidine through a pathway involving asymmetric phosphine catalysis, with our novel l-4-hydroxyproline-derived chiral phosphine mediating the key [3 + 2] annulation. Hydrogenation of the [3 + 2] adduct allowed the rapid formation of the stereochemically dense pyrrolidine ring of (+)-ibophyllidine in excellent yield with exceptionally high levels of both diastereo- and enantioselectivity. We constructed the remainder of the pentacyclic skeleton through an intramolecular alkylation and an intramolecular aza-Morita-Baylis-Hillman reaction.

| S-EPMC3393134 | biostudies-literature

Chiral aminophosphines derived from hydroxyproline and their application in allene-imine [4?+?2] annulation.

Project description:A robust synthetic route from L-hydroxyproline (L-Hyp) to phosphines has established an expandable library of six chiral aminophosphines, which were then applied to the phosphine-catalyzed [4?+?2] allene-imine annulation. The enantioinduction in the annulations-induced by a purely steric effect-were moderate (up to 57% ee). A switch of the reaction site from the ?- to the ?'-carbon atom of the allenoate was observed during the annulations performed using sterically demanding chiral phosphines.

| S-EPMC6599608 | biostudies-literature

Carvone-Derived P-Stereogenic Phosphines: Design, Synthesis, and Use in Allene-Imine [3 + 2] Annulation.

Project description:We have prepared a previously unreported family of P-stereogenic [2.2.1] bicyclic chiral phosphines through straightforward syntheses starting from the natural product carvone. This design rationale prompted the development of an unforeseen C-dealkenylation reaction. We have applied these organocatalysts in the asymmetric syntheses of a bevy of pyrrolines, obtained in high yields and enantioselectivities, including a biologically active small molecule, efsevin.

| S-EPMC6208446 | biostudies-literature

Phosphine-catalyzed [5+1] annulation of ?-sulfonamido-substituted enones with N-sulfonylimines: a facile synthesis of tetrahydropyridines.

Project description:Phosphine-catalyzed [5+1] annulation of ?-sulfonamido-substituted enones with N-sulfonylimines for the synthesis of 1,2,3,6-tetrahydropyridines is developed. The reaction proceeds smoothly under mild reaction conditions to give the annulation products in moderate to excellent yields. Mechanistic exploration of this new annulation shows that the ?-sulfonamido-substituted enone and the N-sulfonylimine serve as C5 and C1 synthons to furnish the annulation, respectively. Using chiral phosphine as the catalyst, an asymmetric variant of the model reaction gave the chiral product in up to 73% ee.

| S-EPMC5892350 | biostudies-literature

Chiral Bifunctional Phosphine Ligand Enabling Gold-Catalyzed Asymmetric Isomerization of Alkyne to Allene and Asymmetric Synthesis of 2,5-Dihydrofuran.

Project description:The asymmetric isomerization of alkyne to allene is the most efficient and the completely atom-economic approach to this class of versatile axial chiral structure. However, the state-of-the-art is limited to tert-butyl alk-3-ynoate substrates that possess requisite acidic propargylic C-H bonds. Reported here is a strategy based on gold catalysis that is enabled by a designed chiral bifunctional biphenyl-2-ylphosphine ligand. It permits isomerization of alkynes with nonacidic α-C-H bonds and hence offers a much-needed general solution. With chiral propargylic alcohols as substrates, 2,5-disubstituted 2,5-dihydrofurans are formed in one step in typically good yields and with good to excellent diastereoselectivities. With achiral substrates, 2,5-dihydrofurans are formed with good to excellent enantiomeric excesses. A novel center-chirality approach is developed to achieve a stereocontrol effect similar to an axial chirality in the designed chiral ligand. The mechanistic studies established that the precatalyst axial epimers are all converted into the catalytically active cationic gold catalyst owing to the fluxional axis of the latter.

| S-EPMC6492927 | biostudies-literature

Phosphine-catalyzed enantioselective synthesis of oxygen heterocycles.

Project description:Chiral phosphepine 1 catalyzes the transformation of an array of hydroxy-2-alkynoates into saturated oxygen heterocycles with good enantioselectivity. Phenols are also shown to participate in such phosphine-catalyzed cyclizations, including an asymmetric variant. This method provides a new approach to the enantioselective synthesis of tetrahydrofurans, tetrahydropyrans, and dihydrobenzopyrans.

| S-EPMC2747790 | biostudies-literature

Phosphine-Initiated General-Base-Catalyzed Quinolone Synthesis.

Project description:Phosphinocatalysis provides a new approach toward 3-substituted-4-quinolones. A simple procedure, which uses Ph3P as an inexpensive catalyst and S-phenyl 2-(N-tosylamido)benzothioates and activated alkynes as starting materials, provides direct access to several 3-aroyl-4-quinolones and methyl 4-quinolone-3-carboxylate esters. The reaction presumably occurs through general base catalysis, with the initial addition of Ph3P to the activated alkyne generating the phosphonium enoate zwitterion, which acts as the strong base that initiates the reaction.

| S-EPMC4509642 | biostudies-literature

Allenes in asymmetric catalysis: asymmetric ring opening of meso-epoxides catalyzed by allene-containing phosphine oxides.

Project description:Unsymmetrically substituted allenes (1,2-dienes) are inherently chiral and can be prepared in optically pure form. Nonetheless, to date the allene framework has not been incorporated into ligands for asymmetric catalysis. Since allenes project functionality differently than either tetrahedral carbon or chiral biaryls, they may create complementary chiral environments. This study demonstrates that optically active, C(2)-symmetric allene-containing bisphosphine oxides can catalyze the addition of SiCl(4) to meso-epoxides with high enantioselectivity. The epoxide opening likely involves generation of a Lewis acidic, cationic (bisphosphine oxide)SiCl(3) complex. The fact that high asymmetric induction is observed suggests that allenes may represent a new platform for the development of ligands and catalysts for asymmetric synthesis.

| S-EPMC2760382 | biostudies-literature

Stereoselective phosphine-catalyzed synthesis of highly functionalized diquinanes.

Project description: Not available

| S-EPMC3821796 | biostudies-literature

Chiral multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita-Baylis-Hillman carbonates with maleimides.

Project description:We have developed a multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita-Baylis-Hillman (MBH) carbonates with maleimides, which can efficiently construct functionalized cyclopentenes bearing three contiguous stereocenters in moderate to excellent yields and excellent diastereo- and enantioselectivities. A plausible mechanism has been also proposed on the basis of control experiments and previous literature.

| S-EPMC3458726 | 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