Showing papers by "Bernd Plietker published in 2008"
109 citations
TL;DR: These results represent the first highly efficient diastereoselective RuO4-catalyzed oxidation of various olefins with chiral auxiliary substituted acrylamides and a variety of structurally diverse enantiomerically enriched diols.
Abstract: Sequential catalysis has evolved as a powerful concept within the past years and allows the more efficient use of catalytically active expensive transition metals in organic synthesis. In this paper we present the stereoselective cross-metathesis−dihydroxylation of various olefins with chiral auxiliary substituted acrylamides. The chiral information (i.e., the auxiliary) introduced in the metathesis reactions allows for a stereoselective subsequent RuO4-catalyzed dihydroxylation. The sequence is concluded by an unusual kinetic resolution of the diastereomeric diols obtained in the oxidation reaction. As a consequence a variety of structurally diverse enantiomerically enriched diols are obtained. To the best of our knowledge the results summarized in this paper represent the first highly efficient diastereoselective RuO4-catalyzed oxidation.
105 citations
Book•
01 Jan 2008
TL;DR: Aromatic Substitutions Nucleophilic Substitution Addition to Carbonyl Compounds Cyclisations Ring Opening Reactions Iron-Catalysis in Biological Environment as mentioned in this paper.
Abstract: Introduction Reductions Oxidations of C,H- and C=C Bonds Oxidative Allylic Oxygenation and Amination Oxidation of Heteroatoms Cross Coupling Reactions Aromatic Substitutions Nucleophilic Substitutions Addition to Carbonyl Compounds Cyclisations Ring Opening Reactions Iron-Catalysis in Biological Environment
67 citations
TL;DR: A new catalytic method based on the use of nucleophilic Fe(-II) complexes is presented and evidence for the formation of an intermediate acyl Fe complex will be presented.
65 citations
57 citations
TL;DR: In this paper, the authors describe a new class of triblock amphiphiles, which consist of a nonpolar biphenyl core and a polar shell based on various generations of monoamino polyglycerol dendrons coupled to the core through amide linkages.
41 citations
TL;DR: A synthetic strategy is presented that allows the selective modular synthesis of natural and non-natural carbohydrates within five synthetic steps starting from readily available starting materials, in which each functional group is orthogonally protected and accessible for further synthetic operations.
Abstract: Carbohydrates are an omnipresent class of highly oxygenated natural products. Due to their wide spectra of biological activities, they have been in the center of synthetic organic chemistry for more than 130 years. During the past 50 years non-natural carbohydrates attracted the interest of various chemists in the fields of organic, biological, and medical chemistry. Especially desoxygenated sugars proved to be an important class of compounds. Up to date, most non-natural analogues are synthesized starting from natural, enantiomerically pure carbohydrates in multistep synthesis. In this report, we present a synthetic strategy that allows the selective modular synthesis of natural and non-natural carbohydrates within five synthetic steps starting from readily available starting materials. Due to a sequential introduction of O- or N-functionalities, a regioselective protection of each new functional group is possible. The key step in the carbohydrate synthesis is a RuO4-catalyzed oxidative cyclization via a...
15 citations
12 Sep 2008
7 citations
TL;DR: In this paper, the authors present the stereoselective cross-metathesis−dihydroxylation of various olefins with chiral auxiliary substituted acrylamides.
Abstract: Sequential catalysis has evolved as a powerful concept within the past years and allows the more efficient use of catalytically active expensive transition metals in organic synthesis. In this paper we present the stereoselective cross-metathesis−dihydroxylation of various olefins with chiral auxiliary substituted acrylamides. The chiral information (i.e., the auxiliary) introduced in the metathesis reactions allows for a stereoselective subsequent RuO4-catalyzed dihydroxylation. The sequence is concluded by an unusual kinetic resolution of the diastereomeric diols obtained in the oxidation reaction. As a consequence a variety of structurally diverse enantiomerically enriched diols are obtained. To the best of our knowledge the results summarized in this paper represent the first highly efficient diastereoselective RuO4-catalyzed oxidation.
3 citations
TL;DR: In this article, strong efforts have been made in developing mild catalytic procedures for the preparation of carboxylic esters, which are the most important functional groups in organic chemistry.
Abstract: Carboxylic esters belong to the most important functional groups in organic chemistry. Strong efforts have been made in developing mild catalytic procedures for their preparation. Among the various...
TL;DR: In this paper, the authors present a strategy that allows the selective modular synthesis of natural and non-natural carbohydrates within five synthetic steps starting from readily available starting materials, where a sequential introduction of O- or N-functionalities, a regioselective protection of each new functional group is possible.
Abstract: Carbohydrates are an omnipresent class of highly oxygenated natural products. Due to their wide spectra of biological activities, they have been in the center of synthetic organic chemistry for more than 130 years. During the past 50 years non-natural carbohydrates attracted the interest of various chemists in the fields of organic, biological, and medical chemistry. Especially desoxygenated sugars proved to be an important class of compounds. Up to date, most non-natural analogues are synthesized starting from natural, enantiomerically pure carbohydrates in multistep synthesis. In this report, we present a synthetic strategy that allows the selective modular synthesis of natural and non-natural carbohydrates within five synthetic steps starting from readily available starting materials. Due to a sequential introduction of O- or N-functionalities, a regioselective protection of each new functional group is possible. The key step in the carbohydrate synthesis is a RuO4-catalyzed oxidative cyclization via a...