Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Diastereo- and Enantioselective Synthesis of Homoallylic Amines Bearing Quaternary Carbon Centers.

ABSTRACT: A Cu-catalyzed method for the efficient enantio- and diastereoselective synthesis of chiral homoallylic amines bearing a quaternary carbon and an alkenylboron is disclosed. Transformations are promoted by a readily prepared (phosphoramidite)-Cu complex and involve bench-stable ?,?-disubstituted allyldiborons and benzyl imines; products are obtained in up to 82% yield, >20:1 dr, and >99:1 er. Reactions proceed via stereodefined boron-stabilized allylic Cu species formed by an enantioselective transmetalation. Utility of the 1-amino-3-alkenylboronate products is highlighted by a variety of synthetic transformations.

SUBMITTER: Green JC

PROVIDER: S-EPMC7180160 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Diastereo- and Enantioselective Synthesis of Homoallylic Amines Bearing Quaternary Carbon Centers.

Green Jacob C JC Zanghi Joseph M JM Meek Simon J SJ

Journal of the American Chemical Society 20200117 4

A Cu-catalyzed method for the efficient enantio- and diastereoselective synthesis of chiral homoallylic amines bearing a quaternary carbon and an alkenylboron is disclosed. Transformations are promoted by a readily prepared (phosphoramidite)-Cu complex and involve bench-stable γ,γ-disubstituted allyldiborons and benzyl imines; products are obtained in up to 82% yield, >20:1 dr, and >99:1 er. Reactions proceed via stereodefined boron-stabilized allylic Cu species formed by an enantioselective tra ...[more]

PMID: 31934766

Similar Datasets

Rhodium-Catalyzed Enantioselective Cycloisomerization to Cyclohexenes Bearing Quaternary Carbon Centers.

Project description:We report a Rh-catalyzed enantioselective cycloisomerization of ?,?-heptadienes to afford cyclohexenes bearing quaternary carbon centers. Rhodium(I) and a new SDP ligand promote chemoselective formation of a cyclohex-3-enecarbaldehyde motif that is inaccessible by the Diels-Alder cycloaddition. Various ?,?-bisallylaldehydes rearrange to generate six-membered rings by a mechanism triggered by aldehyde C-H bond activation. Mechanistic studies suggest a pathway involving regioselective carbometalation and endocyclic ?-hydride elimination.

| S-EPMC4856524 | biostudies-literature

N-Substituted tertiary and O-substituted quaternary carbon stereogenic centers by site-, diastereo- and enantioselective vinylogous Mannich reactions.

Project description:A readily accessible small-molecule phosphine, derived from commercially available starting materials such as an enantiomerically pure amino acid, serves as the precursor to a Ag-based chiral complex that can be prepared and used in situ to promote a variety of enantioselective vinylogous Mannich (EVM) reactions that involve siloxypyrroles as reaction partners. Transformations with unsubstituted nucleophilic components proceed efficiently and with exceptional site- (γ vs α-addition), diastereo- and enantioselectivity [up to 98% yield, generally >98:2 γ/α and diastereomeric ratio (dr) and up to 99:1 enantiomeric ratio (er)]. The first examples of efficient, diastereo- and enantioselective vinylogous Mannich additions with 5-methyl-substituted siloxyfuran, resulting in the formation of O-substituted quaternary carbon stereogenic centers are presented as well. Appreciable efficiency and diastereo- and enantioselectivity (up to >98:2 dr and >99:1 er) is accompanied by formation of α-addition products that can be oxidatively removed.

| S-EPMC5538379 | biostudies-literature

Enantioselective Synthesis of Vicinal All-Carbon Quaternary Centers via Iridium-Catalyzed Allylic Alkylation.

Project description:The development of the first enantioselective transition-metal-catalyzed allylic alkylation providing access to acyclic products bearing vicinal all-carbon quaternary centers is disclosed. The iridium-catalyzed allylic alkylation reaction proceeds with excellent yields and selectivities for a range of malononitrile-derived nucleophiles and trisubstituted allylic electrophiles. The utility of these sterically congested products is explored through a series of diverse chemo- and diastereoselective product transformations to afford a number of highly valuable, densely functionalized building blocks, including those containing vicinal all-carbon quaternary stereocenters.

| S-EPMC6033654 | biostudies-literature

Barbier-type anti-Diastereo- and Enantioselective Synthesis of β-Trimethylsilyl, Fluorinated Methyl, Phenylthio Homoallylic Alcohols.

Project description:Catalytic Asymmetric allylation of aldehydes with functionalized allylic reagents represents an important process in synthetic organic chemistry because the resulting chiral homoallylic alcohols are valuable building blocks in diverse research fields. Despite the obvious advantages of allyl halides as allylation reagent under Barbier-type conditions, catalytic asymmetric version using functionalized allyl halides remains largely underdeveloped. Here, we addressed this issue by employing a chromium-catalysis system. The use of readily available allyl bromides with γ substitutions including trimethylsilyl, fluorinated methyl and phenylthio groups provided an efficient and convenient method to introduce those privileged functionalities into homoallylic alcohols. Good yields, high anti-diastereo- and excellent enantioselectivities were achieved under mild reaction conditions.

| S-EPMC5501818 | biostudies-literature

Synthesis of quaternary carbon stereogenic centers through enantioselective Cu-catalyzed allylic substitutions with vinylaluminum reagents.

Project description:Catalytic enantioselective allylic substitution (EAS) reactions, which involve the use of alkyl- or aryl-substituted vinylaluminum reagents and afford 1,4-dienes containing a quaternary carbon stereogenic center at their C-3 site, are disclosed. The C-C bond-forming transformations are promoted by 0.5-2.5 mol % of sulfonate bearing chiral bidentate N-heterocyclic carbene (NHC) complexes, furnishing the desired products efficiently (66-97% yield of isolated products) and in high site (>98% S(N)2')- and enantioselectivity [up to 99:1 enantiomer ratio (er)]. To the best of our knowledge, the present report puts forward the first cases of allylic substitution reactions that result in the generation of all-carbon quaternary stereogenic centers through the addition of a vinyl unit. The aryl- and vinyl-substituted vinylaluminum reagents, which cannot be prepared in high efficiency through direct reaction with diisobutylaluminum hydride, are accessed through a recently introduced Ni-catalyzed reaction of the corresponding terminal alkynes with the same inexpensive metal-hydride agent. Sequential Ni-catalyzed hydrometalations and Cu-catalyzed C-C bond-forming reactions allow for efficient and selective synthesis of a range of enantiomerically enriched EAS products, which cannot be accessed by previously disclosed strategies (due to inefficient vinylmetal synthesis or low reactivity and/or selectivity with Si-substituted derivatives). The utility of the protocols developed is demonstrated through a concise enantioselective synthesis of natural product bakuchiol.

| S-EPMC2951504 | biostudies-literature

Enantioselective synthesis of cis-hydrobenzofurans bearing all-carbon quaternary stereocenters and application to total synthesis of (‒)-morphine.

Project description:(‒)-Morphine, which is selected as an essential medicine by World Health Organization, is widely applied in the treatment of the pain-related diseases. Due to its synthetically challenging molecular architecture and important clinical role, extensive synthetic studies of morphine-type alkaloids have been conducted. However, catalytic asymmetric total synthesis of (‒)-morphine remains a long-standing challenge. Here, we disclose an efficient enantioselective total synthesis of (‒)-morphine in a longest linear sequence of 16 steps. The key transformation features a highly enantioselective Robinson annulation enabled by our spiro-pyrrolidine catalyst to rapidly construct the densely functionalized cis-hydrodibenzofuran framework containing vicinal stereocenters with an all-carbon quaternary center. This asymmetric approach provides an alternative strategy for the synthesis of (‒)-morphine and its analogues.

| S-EPMC6555830 | biostudies-other

Site- and enantioselective formation of allene-bearing tertiary or quaternary carbon stereogenic centers through NHC-Cu-catalyzed allylic substitution.

Project description:Catalytic enantioselective allylic substitutions that result in addition of an allenyl group (<2% propargyl addition) and formation of tertiary or quaternary C-C bonds are described. Commercially available allenylboronic acid pinacol ester is used. Reactions are promoted by a 5.0-10 mol % loading of sulfonate-bearing chiral bidentate N-heterocyclic carbene (NHC) complexes of copper, which exhibit the unique ability to furnish chiral products arising from the S(N)2' mode of addition. Allenyl-containing products are generated in up to 95% yield, >98% S(N)2' selectivity, and 99:1 enantiomeric ratio (er). Site-selective NHC-Cu-catalyzed hydroboration of enantiomerically enriched allenes and conversion to the corresponding ?-vinyl ketones demonstrates the method's utility.

| S-EPMC3267425 | biostudies-literature

Synthesis of quaternary carbon centers via hydroformylation.

Project description:The application of hydroformylation to the synthesis of quaternary carbon centers is reported. The synthesis of the highly substituted carbon is achieved by applying a catalytic amount of 1. Ligand 1 serves as a catalytic directing group by covalently and reversibly binding to both the substrate and catalyst. The intramolecular nature of the directing group strategy accelerates the hydroformylation reaction such that the reaction is performed at mild temperatures (35-55 degrees C) and with excellent regioselectivity (b:l > 94:6).

| S-EPMC2928406 | biostudies-literature

Enantioselective, Catalytic Multicomponent Synthesis of Homoallylic Amines Enabled by Hydrogen-Bonding and Dispersive Interactions.

Project description:We report a one-step catalytic, enantioselective method for the preparation of homoallylic N-Boc amines directly from acetals. Reactive iminium ion intermediates are generated in situ through the combination of an acetal, a chiral thiourea catalyst, trialkylsilyl triflate, and N-Boc carbamate and are subsequently trapped by a variety of allylsilane nucleophiles. No homoallylic ether byproducts are detected, consistent with allylation of the iminium intermediate being highly favored over allylation of the intermediate oxocarbenium ion. Acetals derived from aromatic aldehydes possessing a variety of functional groups and substitution patterns yield homoallylic amines with excellent levels of enantiomeric enrichment. Experimental and computational data are consistent with an anchoring hydrogen-bond interaction between the protioiminium ion and the amide of the catalyst in the enantiodetermining transition state, and with stereodifferentiation achieved through specific noncovalent interactions (NCIs) with the catalyst pyrenyl moiety. Evidence is provided that the key NCI in the major pathway is a π-stacking interaction, contrasting with the cation-π interactions invoked in previously studied reactions promoted by the same family of aryl-pyrrolidino-H-bond-donor catalysts.

| S-EPMC8547772 | biostudies-literature

Redox-triggered C-C coupling of alcohols and vinyl epoxides: diastereo- and enantioselective formation of all-carbon quaternary centers via tert-(hydroxy)-prenylation.

Project description:Iridium catalyzed primary alcohol oxidation triggers reductive C-O bond cleavage of isoprene oxide to form aldehyde-allyliridium pairs that combine to form products of tert-(hydroxy)-prenylation, a motif found in >2000 terpenoid natural products. Curtin-Hammett effects are exploited to enforce high levels of anti-diastereo- and enantioselectivity in the formation of an all-carbon quaternary center. The present redox-triggered carbonyl additions occur in the absence of stoichiometric byproducts, premetalated reagents, and discrete alcohol-to-aldehyde redox manipulations.

| S-EPMC4090370 | 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