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New Publications in Angewandte Chemie

 

(1) Enantioselective Rhodium-Catalyzed Synthesis of Branched Allylic Amines by Intermolecular Hydroamination of Terminal Allenes

 

Branching out: The rhodium-catalyzed enantioselective hydroamination of monosubstituted allenes with anilines permits the atom-economic synthesis of valuable branched allylic amines. In contrast to previous linear selective allene hydroaminations, a RhI/Josiphos catalyst system (see scheme; cod=1,5-cyclooctadiene, DCE=1,2-dichloroethane) allows branched allylic amines to be obtained with perfect regioselectivity, high yield, and good enantioselectivity.

M. L. Cooke, Kun Xu, B. Breit, Angew. Chem. 2012, 124, 11034-11037; (link) Angew. Chem. Int. Ed. 2012, 51, 10876-10879. (link)

 

(2) Mechanistic Insights into a Supramolecular Self-Assembling Catalyst System: Evidence for Hydrogen-Bonding during Rhodium-Catalyzed Hydroformylation

The structural integrity and flexibility provided by intermolecular hydrogen bonds leads to the outstanding properties of the 6-diphenylphosphinopyridin-(2H)-1-one ligand (see scheme) in the rhodium-catalyzed hydroformylation of terminal alkenes, as demonstrated by the combination of spectroscopic methods and DFT computations. Hydrogen bonds were also detected in a competent intermediate of the catalytic cycle.

U. Gellrich, W. Seiche, M. Keller, B. Breit, Angew. Chem. 2012, 124, 11195-11200; (link) Angew. Chem. Int. Ed. 2012, 51, 11033-11038. (link)

 

(3) Preparation of Alkylmagnesium Reagents from Alkenes through Hydroboration and Boron-Magnesium Exchange

Tolerant: Alkylmagnesium reagents can be synthesized from alkenes through a sequence of hydroboration and subsequent boron–magnesium exchange using a method that tolerates different functional groups (see scheme). The resulting alkylmagnesium reagents can be used in carbon–carbon bond forming reactions, such as alkylation reactions or transition-metal-catalyzed cross-coupling reactions.

M. Reichle, B. Breit, Angew. Chem. 2012, 124, 5828-5832; (link) Angew. Chem. Int. Ed. 2012, 51, 5730-5734. (link) highlighted in SynFacts as Synfact of the Month September (link)

 

(4) Tandem Rhodium-Catalyzed Hydroformylation-Hydrogenation of Alkenes by Employing a Cooperative Ligand System

Dual action: A multifunctional rhodium catalyst system enables the simultaneous catalysis of two distinct transformations, hydroformylation of an alkene and reduction of an aldehyde, in a highly selective manner. This one-pot/two-step process is controlled by the cooperative action of two different supramolecular ligand systems and transforms terminal alkenes into C1-chain-elongated linear

D. Fuchs, G. Rousseau, L. Diab, U. Gellrich, B. Breit, Angew. Chem. 2012, 124, 2220-2224; (link) Angew. Chem. Int. Ed. 2012, 51, 2178-2182. (link)

 

 

2 PostDoc Positions available

 

Postdoctoral Position (E13) available for a collaboration project with Syngenta Crop Science
The candidate  will have to develop selective hydroformylation reactions of specifically functionalized alkenes as a key step for heterocycle synthesis. Experience in organic synthesis and/or transition metal catalysis and/or carbonylation chemistry is of advantage. Please send your application including two letters of recommendation to bernhard.breit@chemie.uni-freiburg.de

 

In the framework of SFB 992 Medical Epigenetics (MEDEP): From basic mechanisms to clinical applications we offer one PostDoc postion (E13) in Synthetic Organic Chemistry

Topic: Synthesis of potent and selective small molecules that regulate epigenetic pathways and can be utilised as chemical probes for cellular and animal studies.

Excellent candidates, please contact Prof. Dr. B. Breit (bernhard.breit@chemie.uni-freiburg.de) directly.

 

Übung Vorlesung Reaktionmechanismen


Inhalt der Übungen: Besprechung des mechanistischen Verlaufs der einzelnen Präparate

Beginn: Mo, 30.04.12, 9-10 Uhr, SR123/124

Übung 1: Radikalische Substitution am gesättigten C-Atom, Präparate 1-1 bis 1-8

 

(Gesamt)-Nachklausur OCI, 04.04.2012


9-12 Uhr HS Chemie

 

OGP-LA 2012 (WPO2001)


Anmeldefrist bis: 31.01.2012, Aushang

 

Open House - Vorstellung der B.Sc.-Themen


Wann: Mittwoch, 18.01.12, 18.15 Uhr

Wo: SR704

Was: Vorstellung möglicher B.Sc.-Themen bei Brezeln und Bier

 

openhouse

 

 

Ergebnis Wiederholungsklausur Teil A zur Vorlesung Organische Experimentalchemie I vom 04.01.2012

 

Ergebnisliste: Erdgeschoß Chemiehochhaus,  "Schwarzes Brett" vor den Aufzügen

Einsicht: Donnerstag, 05.01.2012, 14.00 Uhr, SR704 oder im Sekretariat von Herrn Prof. Breit

 


Ergebnis Klausur Teil A zur Vorlesung Organische Experimentalchemie I vom 17.12.2011

 

Ergebnisliste: Erdgeschoß Chemiehochhaus,  "Schwarzes Brett" vor den Aufzügen

Einsicht: Dienstag, 20.12.2011, 13.00-14.00 Uhr, SR44/45

 

 


New Publication in JACS


Enantioselective Synthesis of Branched Allylic Esters via Rhodium-Catalyzed Coupling of Allenes with Carboxylic Acids

jacs_11
 

 

We report on the first intermolecular asymmetric catalytic regio- and enantioselective addition of carboxylic acids to terminal allenes to form valuable branched allylic esters, employing a rhodium(I)/(R,R)-DIOP catalyst system.

P. Koschker, A. Lumbroso, B. Breit* J. Am. Chem. Soc. 2011, ASAP, DOI: 10.1021/ja210149g

 

 

New Angewandte Hot Paper


Divergent Regioselectivity in the Synthesis of Trisubstituted Allylic Alcohols by Nickel- and Ruthenium-Catalyzed Alkyne Hydrohydroxymethylation with Formaldehyde

  ac.jpg

 

Stoichiometric metals banned: Nonsymmetrically disubstituted alkynes were converted into primary trisubstituted allylic alcohols upon exposure to paraformaldehyde in the presence of nickel or ruthenium catalysts, which exhibit complementary regioselectivity and complete stereoselectivity in the absence of exogenous reducing agents (see scheme).

C. C. Bausch, R. L. Patman, B. Breit*, M. J. Krische* Angew. Chem. 2011, 123(25), 5805-5808

DOI: 10.1002/anie.201101496

 

 

New Publication in JACS


Redox-Neutral Atom-Economic Rhodium-Catalyzed Coupling of Terminal Alkynes with Carboxylic Acids Toward Branched Allylic Esters

jacs

Alexandre Lumbroso, Philipp Koschker, Nicolas R. Vautravers and Bernhard Breit JACS 2011, 133, 2386-2389, pdf

 

 

 Bachelor- und Mitarbeiterprojekte

Group             Bachelor.png

 

 

Zu finden:

 Posterstellwand vor dem HS Chemie
&

Chemiehochhaus 2. OG vor dem OFP-Saal

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