Browse
Submit Data
Databases
API
Help

Dataset Information

33 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Asymmetric petasis reactions catalyzed by chiral biphenols.

ABSTRACT: Chiral biphenols catalyze the enantioselective Petasis reaction of alkenyl boronates, secondary amines, and ethyl glyoxylate. The reaction requires the use of 15 mol % of (S)-VAPOL as the catalyst, alkenyl boronates as nucleophiles, ethyl glyoxylate as the aldehyde component, and 3 A molecular sieves as an additive. The chiral alpha-amino ester products are obtained in good yields (71-92%) and high enantiomeric ratios (89:11-98:2). Mechanistic investigations indicate single ligand exchange of acyclic boronate with VAPOL and tetracoordinate boronate intermediates.

SUBMITTER: Lou S

PROVIDER: S-EPMC2440570 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Asymmetric petasis reactions catalyzed by chiral biphenols.

Lou Sha S Schaus Scott E SE

Journal of the American Chemical Society 20080507 22

Chiral biphenols catalyze the enantioselective Petasis reaction of alkenyl boronates, secondary amines, and ethyl glyoxylate. The reaction requires the use of 15 mol % of (S)-VAPOL as the catalyst, alkenyl boronates as nucleophiles, ethyl glyoxylate as the aldehyde component, and 3 A molecular sieves as an additive. The chiral alpha-amino ester products are obtained in good yields (71-92%) and high enantiomeric ratios (89:11-98:2). Mechanistic investigations indicate single ligand exchange of ac ...[more]

PMID: 18459782

Similar Datasets

Asymmetric Petasis Borono-Mannich Allylation Reactions Catalyzed by Chiral Biphenols.

Project description:Chiral biphenols catalyze the asymmetric Petasis borono-Mannich allylation of aldehydes and amines through the use of a bench-stable allyldioxaborolane. The reaction proceeds via a two-step, one-pot process and requires 2-8 mole % of 3,3'-Ph2 -BINOL as the optimal catalyst. Under microwave heating the reaction affords chiral homoallylic amines in excellent yields (up to 99 %) and high enantioselectivies (er up to 99:1). The catalytic reaction is a true multicomponent condensation reaction whereas both the aldehyde and the amine can possess a wide range of structural and electronic properties. Use of crotyldioxaborolane in the reaction results in stereodivergent products with anti- and syn-diastereomers both in good diastereoselectivities and enantioselectivities from the corresponding E- and Z-borolane stereoisomers.

| S-EPMC5716625 | biostudies-literature

Asymmetric propargylation of ketones using allenylboronates catalyzed by chiral biphenols.

Project description:Chiral biphenols catalyze the enantioselective asymmetric propargylation of ketones using allenylboronates. The reaction uses 10 mol % of 3,3'-Br(2)-BINOL as the catalyst and allenyldioxoborolane as the nucleophile, in the absence of solvent, and under microwave irradiation to afford the homopropargylic alcohol. The reaction products are obtained in good yields (60-98%) and high enantiomeric ratios (3:1-99:1). Diastereoselective propargylations using chiral racemic allenylboronates result in good diastereoselectivities (dr >86:14) and enantioselectivities (er >92:8) under the catalytic conditions.

| S-EPMC3155969 | biostudies-literature

The mechanism and an improved asymmetric allylboration of ketones catalyzed by chiral biphenols.

Project description: Not available

| S-EPMC2819187 | biostudies-literature

Enantioselective Multicomponent Condensation Reactions of Phenols, Aldehydes, and Boronates Catalyzed by Chiral Biphenols.

Project description:Chiral diols and biphenols catalyze the multicomponent condensation reaction of phenols, aldehydes, and alkenyl or aryl boronates. The condensation products are formed in good yields and enantioselectivities. The reaction proceeds via an initial Friedel-Crafts alkylation of the aldehyde and phenol to yield an ortho-quinone methide that undergoes an enantioselective boronate addition. A cyclization pathway was discovered while exploring the scope of the reaction that provides access to chiral 2,4-diaryl chroman products, the core of which is a structural motif found in natural products.

| S-EPMC4671505 | biostudies-literature

Enantioselective addition of boronates to acyl imines catalyzed by chiral biphenols.

Project description:On the big screen: A chiral biphenol catalyst screening protocol was developed for the rapid identification of enantioselective nucleophilic boronate reactions with acyl imines (see scheme). The approach successfully identified a unique catalyst for the reaction of aryl, vinyl, and alkynyl boronates. Mechanistic studies demonstrate boronate ligand exchange with the catalyst is necessary for activation towards nucleophilic addition.

| S-EPMC2819183 | biostudies-literature

Enantioselective addition of boronates to o-quinone methides catalyzed by chiral biphenols.

Project description:Chiral biphenols were found to catalyze the enantioselective asymmetric addition of aryl- or alkenylboronates to o-quinone methides. Substituted 2-styryl phenols were obtained in good yields (up to 95%) with high enantiomeric ratios (up to 98:2) in the presence of 10 mol % 3,3'-Br(2)-BINOL. A two-step synthesis of (S)-4-methoxydalbergione in good yield and selectivity was achieved.

| S-EPMC4655814 | biostudies-literature

Asymmetric Traceless Petasis Borono-Mannich Reactions of Enals: Reductive Transposition of Allylic Diazenes.

Project description:The traceless Petasis borono-Mannich reaction of enals, sulfonylhydrazines, and allylboronates, catalyzed by chiral biphenols, results in an asymmetric reductive transposition of the in situ generated allylic diazene. Acyclic 1,4-diene products bearing either alkyl- or aryl-substituted benzylic stereocenters are afforded in excellent yields and enantiomeric ratios of up to 99:1. The use of crotylboronates in the reaction results in concomitant formation of two stereocenters in either a 1,4-syn or anti relationship from the corresponding E- or Z-crotylboronate used in the reaction. The use of β-monosubstituted enals in the asymmetric traceless Petasis borono-Mannich reaction of crotylboronates installs tertiary methyl-bearing stereocenters in good yields and high enantioselectivities.

| S-EPMC5739942 | biostudies-literature

Catalytic diastereoselective petasis reactions.

Project description:Multicomponent Petasis reactions: the first diastereoselective Petasis reaction catalyzed by chiral biphenols that enables the synthesis of syn and anti β-amino alcohols in pure form has been developed. The reaction exploits a multicomponent approach that involves boronates, α-hydroxy aldehydes, and amines.

| S-EPMC4673970 | biostudies-literature

Enantioselective synthesis of anti- and syn-homopropargyl alcohols via chiral Bronsted acid catalyzed asymmetric allenylboration reactions.

Project description:Chiral Brønsted acid catalyzed asymmetric allenylboration reactions are described. Under optimized conditions, anti-homopropargyl alcohols 2 are obtained in high yields with excellent diastereo- and enantioselectivities from stereochemically matched aldehyde allenylboration reactions with (M)-1 catalyzed by the chiral phosphoric acid (S)-4. The syn-isomers 3 can also be obtained in good diastereoselectivities and excellent enantioselectivities from the mismatched allenylboration reactions of aromatic aldehydes using (M)-1 in the presence of the enantiomeric phosphoric acid (R)-4. The stereochemistry of the methyl group introduced into 2 and 3 is controlled by the chirality of the allenylboronate (M)-1, whereas the configuration of the new hydroxyl stereocenter is controlled by the enantioselectivity of the chiral phosphoric acid catalyst used in these reactions. The synthetic utility of this methodology was further demonstrated in highly diastereoselective syntheses of a variety of anti, anti-stereotriads, the direct synthesis of which has constituted a significant challenge using previous generations of aldol and crotylmetal reagents.

| S-EPMC3474359 | biostudies-literature

Pipecolic acid-catalyzed direct asymmetric mannich reactions.

Project description:Mannich reactions between aldehydes and N-p-methoxyphenyl-protected alpha-imino ethyl glyoxylate have been performed using (S)-pipecolic acid as catalyst. The reactions give both syn- and anti-products (dr=1.4-2:1) with high enantioselectivities (>98% ee). In contrast, (S)-proline-catalyzed reactions give mainly syn-products with high enantioselectivities. Computational studies reveal that the energetic preference between the transition structures involving the s-cis-enamine and the s-trans-enamine is smaller for the pipecolic acid as compared to proline, yielding the (2S,3R)-anti and the (2S,3S)-syn Mannich product in nearly equal amounts.

| S-EPMC3164113 | 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