Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions.

ABSTRACT: Four catalysts based on new amides of chiral 1,2-diamines and 2-sulfobenzoic acid have been developed. The alkali-metal salts of these betaine-like amides are able to form imines with enones, which are activated by Lewis acid interaction for nucleophilic attack by 4-hydroxycoumarin. The addition of 4-hydroxycoumarin to enones gives ee's up to 83% and almost quantitative yields in many cases. This novel type of catalysis provides an effective alternative to conventional primary amino catalysis were strong acid additives are essential components.

SUBMITTER: Leven M

PROVIDER: S-EPMC3566766 | biostudies-other | 2013

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Homo- and heterodehydrocoupling of phosphines mediated by alkali metal catalysts.

Project description:Catalytic chemistry that involves the activation and transformation of main group substrates is relatively undeveloped and current examples are generally mediated by expensive transition metal species. Herein, we describe the use of inexpensive and readily available tBuOK as a catalyst for P-P and P-E (E = O, S, or N) bond formation. Catalytic quantities of tBuOK in the presence of imine, azobenzene hydrogen acceptors, or a stoichiometric amount of tBuOK with hydrazobenzene, allow efficient homodehydrocoupling of phosphines under mild conditions (e.g. 25 °C and < 5 min). Further studies demonstrate that the hydrogen acceptors play an intimate mechanistic role. We also show that our tBuOK catalysed methodology is general for the heterodehydrocoupling of phosphines with alcohols, thiols and amines to generate a range of potentially useful products containing P-O, P-S, or P-N bonds.

| S-EPMC6594957 | biostudies-literature

Squaramide-catalyzed enantioselective Michael addition of diphenyl phosphite to nitroalkenes.

Project description: Not available

| S-EPMC3930154 | biostudies-literature

Lipase-Catalyzed Phospha-Michael Addition Reactions under Mild Conditions.

Project description:Organophosphorus compounds are the core structure of many active natural products. The synthesis of these compounds is generally achieved by metal catalysis requiring specifically functionalized substrates or harsh conditions. Herein, we disclose the phospha-Michael addition reaction of biphenyphosphine oxide with various substituted β-nitrostyrenes or benzylidene malononitriles. This biocatalytic strategy provides a direct route for the synthesis of C-P bonds with good functional group compatibility and simple and practical operation. Under the optimal conditions (styrene (0.5 mmol), biphenyphosphine oxide (0.5 mmol), Novozym 435 (300 U), and EtOH (1 mL)), lipase leads to the formation of organophosphorus compounds in yields up to 94% at room temperature. Furthermore, we confirm the role of the catalytic triad of lipase in this phospha-Michael addition reaction. This new biocatalytic system will have broad applications in organic synthesis.

| S-EPMC9698776 | biostudies-literature

6-exo-trig Michael addition-lactonizations for catalytic enantioselective chromenone synthesis.

Project description:The catalytic enantioselective 6-exo-trig Michael addition-lactonization of enone-acid substrates to form cis-chromenones with high diastereo- and enantiocontrol was developed using the commercially available isothiourea tetramisole. An acidic workup proved necessary to minimize product epimerization and maximize product er, providing cis-chromenones in excellent yield, and with excellent diastereo- and enantioselectivity.

| S-EPMC5358503 | biostudies-literature

Enantioselective Michael addition/iminium ion cyclization cascades of tryptamine-derived ureas.

Project description:A Michael addition/iminium ion cyclization cascade of enones with tryptamine-derived ureas under BINOL phosphoric acid (BPA) catalysis is reported. The cascade reaction tolerates a wide variety of easily synthesized tryptamine-derived ureas, including those bearing substituents on the distal nitrogen atom of the urea moiety, affording polyheterocyclic products in good yields and good to excellent enantioselectivities.

| S-EPMC3931331 | biostudies-literature

Squaramide-catalyzed enantioselective Michael addition of masked acyl cyanides to substituted enones.

Project description:Masked acyl cyanide (MAC) reagents are shown to be effective umpolung synthons for enantioselective Michael addition to substituted enones. The reactions are catalyzed by chiral squaramides and afford adducts in high yields (90-99%) and with excellent enantioselectivities (85-98%). The addition products are unmasked to produce dicyanohydrins that, upon treatment with a variety of nucleophiles, provide γ-keto acids, esters, and amides. The use of this umpolung synthon has enabled, in enantiomerically enriched form, the first total synthesis of the prenylated phenol (+)-fornicin C.

| S-EPMC3968543 | biostudies-literature

Enantioselective Synthesis of (R)-Sitagliptin via Phase-Transfer Catalytic aza-Michael Addition

Project description: Not available

| S-EPMC10993359 | biostudies-literature

Enantioselective Michael Addition of Aldehydes to Maleimides Organocatalyzed by a Chiral Primary Amine-Salicylamide.

Project description:A primary amine-salicylamide derived from chiral trans-cyclohexane-1,2-diamine was used as an organocatalyst for the enantioselective conjugate addition of aldehydes, mainly ?,?-disubstituted to N-substituted maleimides. The reaction was performed in toluene as a solvent at room temperature. The corresponding enantioenriched adducts were obtained with high yields and enantioselectivities up to 94%. Theoretical calculations were used to justify the stereoinduction.

| S-EPMC6320823 | biostudies-other

Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions.

Project description:The catalytic activity of different supported bifunctional thioureas on sulfonylpolystyrene resins has been studied in the nitro-Michael addition of different nucleophiles to trans-?-nitrostyrene derivatives. The activity of the catalysts depends on the length of the tether linking the chiral thiourea to the polymer. The best results were obtained with the thiourea derived from (L)-valine and 1,6-hexanediamine. The catalysts can be used in only 2 mol % loading, and reused for at least four cycles in neat conditions. The ball milling promoted additions also worked very well.

| S-EPMC4902052 | biostudies-literature

Markovnikov alcohols via epoxide hydroboration by molecular alkali metal catalysts.

Project description:Synthesis of branched "Markovnikov" alcohols is crucial to various chemical industries. The catalytic reduction of substituted epoxides under mild conditions is a highly attractive method for preparing such alcohols. Classical methods based on heterogeneous or homogeneous transition metal-catalyzed hydrogenation, hydroboration, or hydrosilylation usually suffer from poor selectivity, reverse regioselectivity, limited functional group compatibility, high cost, and/or low availability of the catalysts. Here we report the discovery of highly regioselective hydroboration of nonsymmetrical epoxides catalyzed by ligated archetypal reductants in organic chemistry ‒ alkali metal triethylborohydrides. The chemoselectivity and turnover efficiencies of the present catalytic approach are excellent. Thus, terminal and internal epoxides with ene, yne, aryl, and halo groups were selectively and quantitatively reduced under a substrate-to-catalyst ratio (S/C) of up to 1000. Mechanistic investigations point to a mechanism reminiscent of frustrated Lewis pair action on substrates in which a nucleophile and Lewis acid act cooperatively on the substrate.

| S-EPMC9515598 | 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