Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Enantioselective carbonyl allylation, crotylation, and tert-prenylation of furan methanols and furfurals via iridium-catalyzed transfer hydrogenation.

ABSTRACT: 5-Substituted-2-furan methanols 1a-c are subject to enantioselective carbonyl allylation, crotylation and tert-prenylation upon exposure to allyl acetate, alpha-methyl allyl acetate, or 1,1-dimethylallene in the presence of an ortho-cyclometalated iridium catalyst modified by (R)-Cl,MeO-BIPHEP, (R)-C3-TUNEPHOS, and (R)-C3-SEGPHOS, respectively. In the presence of 2-propanol, but under otherwise identical conditions, the corresponding substituted furfurals 2a-c are converted to identical products of allylation, crotylation, and tert-prenylation. Optically enriched products of carbonyl allylation, crotylation, and reverse prenylation 3b, 4b, and 5b were subjected to Achmatowicz rearrangement to furnish the corresponding gamma-hydroxy-beta-pyrones 6a-c, respectively, with negligible erosion of enantiomeric excess.

SUBMITTER: Bechem B

PROVIDER: S-EPMC2830394 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Enantioselective carbonyl allylation, crotylation, and tert-prenylation of furan methanols and furfurals via iridium-catalyzed transfer hydrogenation.

Bechem Benjamin B Patman Ryan L RL Hashmi A Stephen K AS Krische Michael J MJ

The Journal of organic chemistry 20100301 5

5-Substituted-2-furan methanols 1a-c are subject to enantioselective carbonyl allylation, crotylation and tert-prenylation upon exposure to allyl acetate, alpha-methyl allyl acetate, or 1,1-dimethylallene in the presence of an ortho-cyclometalated iridium catalyst modified by (R)-Cl,MeO-BIPHEP, (R)-C3-TUNEPHOS, and (R)-C3-SEGPHOS, respectively. In the presence of 2-propanol, but under otherwise identical conditions, the corresponding substituted furfurals 2a-c are converted to identical products ...[more]

PMID: 20131774

Similar Datasets

Diastereo- and Enantioselective Iridium Catalyzed Carbonyl (?-Cyclopropyl)allylation via Transfer Hydrogenation.

Project description:The first examples of diastereo- and enantioselective carbonyl ?-(cyclopropyl)allylation are reported. Under the conditions of iridium catalyzed transfer hydrogenation using the chiral precatalyst (R)-Ir-I modified by SEGPHOS, carbonyl ?-(cyclopropyl)allylation may be achieved with equal facility from alcohol or aldehyde oxidation levels. This methodology provides a conduit to hitherto inaccessible inaccessible enantiomerically enriched cyclopropane-containing architectures.

| S-EPMC4627847 | biostudies-literature

Iridium Catalyzed Hydro-hydroxyalkylation of Butadiene: Carbonyl Crotylation.

Project description:Exposure of alcohols 1a-1i to butadiene in the presence of a cyclometallated iridium catalyzed derived from allyl acetate, 4-methoxy-3-nitrobenzoic acid and BIPHEP (2,2'-bis(diphenylphosphino)biphenyl) results in hydrogen transfer to generate aldehyde-allyliridium pairs, which engage in C-C coupling to form products of carbonyl crotylation. Under related conditions using 1,4-butanediol as hydrogen donor, butadiene reductively couples to aldehydes 2e-2g and 2i to furnish carbonyl crotylation products 3e-3g and 3i. Thus, butadiene mediated carbonyl crotylation occurs with equal facility from the alcohol or aldehyde oxidation level with complete levels of branched regioselectivity.

| S-EPMC3001632 | biostudies-literature

Ruthenium-BINAP Catalyzed Alcohol C-H tert-Prenylation via 1,3-Enyne Transfer Hydrogenation: Beyond Stoichiometric Carbanions in Enantioselective Carbonyl Propargylation.

Project description:The chiral ruthenium complex formed in situ from (TFA)2Ru(CO)(PPh3)2 and (R)-BINAP is found to catalyze the enantioselective C-C coupling of diverse primary alcohols with the 1,3-enyne, TMSC?CC(Me)?CH2, to form secondary homopropargyl alcohols bearing gem-dimethyl groups. All reagents for this byproduct-free coupling are inexpensive and commercially available, making this protocol a practical alternative to stoichiometric carbanions in enantioselective carbonyl reverse prenylation.

| S-EPMC4920142 | biostudies-literature

Enhanced anti-diastereo- and enantioselectivity in alcohol-mediated carbonyl crotylation using an isolable single component iridium catalyst.

Project description:The cyclometalated iridium complex (S)-I derived from [Ir(cod)Cl](2), 4-cyano-3-nitrobenzoic acid, allyl acetate, and (S)-SEGPHOS is conveniently isolated by precipitation or through conventional silica gel flash chromatography. This single-component precatalyst allows alcohol mediated carbonyl crotylations to be performed at significantly lower temperature, resulting in enhanced levels of anti-diastereo- and enantioselectivity. Most significantly, the chromatographically isolated precatalyst (S)-I enables carbonyl crotylations that are not possible under previously reported conditions involving in situ generation of (S)-I.

| S-EPMC3064714 | biostudies-literature

Iridium-catalyzed anti-diastereo- and enantioselective carbonyl (trimethylsilyl)allylation from the alcohol or aldehyde oxidation level.

Project description:Using the ortho-cyclometalated pi-allyl iridium precatalyst (R)-I derived from [Ir(cod)Cl](2), 4-cyano-3-nitrobenzoic acid, (R)-SEGPHOS, and allyl acetate, enantioselective transfer hydrogenation of alpha-(trimethylsilyl)allyl acetate in the presence of aldehydes 2a-i mediated by 2-propanol delivers products of (trimethylsilyl)allylation 4a-i in good isolated yields and with exceptional levels of anti-diastereoselectivity and enantioselectivity (90-99% ee). In the absence of 2-propanol, but under otherwise identical reaction conditions, carbonyl (trimethylsilyl)allylation is achieved directly from the alcohol oxidation level to furnish an equivalent set of adducts 4a-i with roughly equivalent isolated yields and stereoselectivities. To evaluate the synthetic utility of the reaction products 4a-i, adduct 4g was converted to the 1,4-ene-diol 5g via dioxirane-mediated oxidative desilylation with allylic transposition, the allylic alcohol 6g via protodesilylation with allylic transposition, and the gamma-lactam 7g via chlorosulfonyl isocyanate-mediated cycloaddition.

| S-EPMC2904607 | biostudies-other

Asymmetric alcohol C-H allylation and syn-crotylation: C9-C20 of tetrafibricin.

Project description:The C9-C20 segment of the fibrinogen receptor inhibitor tetrafibricin was prepared in 10 steps (longest linear sequence). Ruthenium catalyzed enantioselective syn-crotylation is used to construct C9-C13. Iridium catalyzed asymmetric alcohol C-H allylation of a commercial malic acid derived alcohol is used to construct C14-C20. Recovery and recycling of the iridium catalyst is described.

| S-EPMC3932543 | biostudies-literature

Enantioselective ruthenium-catalyzed carbonyl allylation via alkyne-alcohol C-C bond-forming transfer hydrogenation: allene hydrometalation vs oxidative coupling.

Project description:Chiral ruthenium(II) complexes modified by Josiphos ligands catalyze the reaction of alkynes with primary alcohols to form homoallylic alcohols with excellent control of regio-, diastereo-, and enantioselectivity. These processes represent the first examples of enantioselective carbonyl allylation using alkynes as allylmetal equivalents.

| S-EPMC4385519 | biostudies-literature

Direct generation of acyclic polypropionate stereopolyads via double diastereo- and enantioselective iridium-catalyzed crotylation of 1,3-diols: beyond stepwise carbonyl addition in polyketide construction.

Project description:Under the conditions of transfer hydrogenation employing the cyclometalated iridium catalyst (R)-I derived from [Ir(cod)Cl](2), allyl acetate, 4-cyano-3-nitrobenzoic acid, and the chiral phosphine ligand (R)-SEGPHOS, α-methylallyl acetate engages 1,3-propanediol (1a) and 2-methyl-1,3-propanediol (1b) in double carbonyl crotylation from the alcohol oxidation level to deliver the C(2)-symmetric and pseudo-C(2)-symmetric stereopolyads 2a and 3a, respectively, with exceptional control of anti-diastereoselectivity and enantioselectivity. Notably, the polypropionate stereopentad 3a is formed predominantly as 1 of 16 possible stereoisomers. Desymmetrization of 3a is readily achieved upon iodoetherification to form pyran 4. The direct generation of 3a enables a dramatically simplified approach to previously prepared polypropionate substructures, as demonstrated by the synthesis of C19-C27 of rifamycin S (eight steps, originally prepared in 26 steps) and C19-C25 of scytophycin C (eight steps, originally prepared in 15 steps). The present transfer hydrogenation protocol represents an alternative to chiral auxiliaries, chiral reagents, and premetalated nucleophiles in polyketide construction.

| S-EPMC3154980 | biostudies-literature

Iridium-Catalyzed Enantioselective Intermolecular Indole C2-Allylation.

Project description:The enantioselective intermolecular C2-allylation of 3-substituted indoles is reported for the first time. This directing group-free approach relies on a chiral Ir-(P, olefin) complex and Mg(ClO4 )2 Lewis acid catalyst system to promote allylic substitution, providing the C2-allylated products in typically high yields (40-99?%) and enantioselectivities (83-99?% ee) with excellent regiocontrol. Experimental studies and DFT calculations suggest that the reaction proceeds via direct C2-allylation, rather than C3-allylation followed by in situ migration. Steric congestion at the indole-C3 position and improved ?-? stacking interactions have been identified as major contributors to the C2-selectivity.

| S-EPMC7217203 | biostudies-literature

Iridium-catalyzed regioselective and enantioselective allylation of trimethylsiloxyfuran.

Project description:We report the regio- and enantioselective allylation of an ester enolate, trimethylsiloxyfuran. This enolate reacts at the 3-position with linear aromatic allylic carbonates or aliphatic allylic benzoates to form the branched substitution products in the presence of a metallacyclic iridium catalyst. This process provides access to synthetically important 3-substituted butenolides in enantioenriched form. Stoichiometric reactions of the allyliridium intermediate suggest that the trimethylsiloxyfuran is activated by the carboxylate leaving group.

| S-EPMC3487469 | 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