Zwitterionic Metal-Enolate or Equivalent: Generation and Capture

Functionalized ketones and their derivatives are very important building blocks in organic synthesis and material chemistry. The development of novel methodology for the chemo-, regio-, diastereo-, stereo- and enantioselective synthesis of functionalized ketones and their derivatives is the continuous endeavor of organic chemists. Herein we highlight the new approach that was recently initiated and developed by our group for the synthesis of (enantioenriched) ketones and related derivatives based on zwitterionic metal-enolate (ZME) chemistry.

Polymer Supported Proline-Based Organocatalysts in Asymmetric Aldol Reactions: A Review

The use of proline-based organocatalysts has acquired significant importance in organic synthesis, especially in enantioselective synthesis. Proline and its derivatives are proven to be quite effective chiral organocatalysts for a variety of transformations including the aldol reaction, which is considered as one of the important C-C bond forming reactions in organic synthesis. The use of chiral organocatalysts has several advantages over its metal-mediated analogues. Subsequently, a large number of highly efficient proline-based organocatalysts including polymer-supported chiral analogues have been identified for aldol reaction. The use of polymer-supported organocatalysts exhibited remarkable stability under the reaction conditions and offered the best results particularly in terms of its recyclability and reusability. These potential benefits along with its economic and green chemistry advantages have led to the search for many polymer-supported proline catalysts. In this review, recent developments in exploring various polymer immobilized proline-based chiral organocatalysts for asymmetric aldol reactions are described.

Identification of Cuticular and Web Lipids of the Spider Argiope bruennichi

Emerging evidence shows that the cuticular and silk lipids of spiders are structurally more diverse than those of insects, although only a relatively low number of species have been investigated so far. As in insects, such lipids might play a role as signals in various contexts. The wasp spider Argiope bruennichi has probably the best investigated chemical communication system within spiders, including the known structure of the female sex pheromone. Recently we showed that kin-recognition in A. bruennichi could be mediated through the cuticular compounds consisting of hydrocarbons and, to a much larger proportion, of wax esters. By use of mass spectrometry and various derivatization methods, these were identified as esters of 2,4-dimethylalkanoic acids and 1-alkanols of varying chain lengths, such as tetradecyl 2,4-dimethylheptadecanoate. A representative enantioselective synthesis of this compound was performed which proved the identifications and allowed us to postulate that the natural enantiomer likely has the (2R,4R)-configuration. Chemical profiles of the silk and cuticular lipids of females were similar, while male cuticular profiles differed from those of females. Major components of the male cuticular lipids were tridecyl 2,4-dimethyl-C17-19 alkanoates, whereas those of females were slightly longer, comprising tridecyl 2,4-dimethyl-C19-21 alkanoates. In addition, minor female-specific 4-methylalkyl esters were detected.

Transition-Metal-Catalyzed Enantioselective Synthesis of Indoles from 2-Alkynylanilines

Optically active indole derivatives are ubiquitous in natural products and widely recognized as privileged components in pharmacologically relevant compounds. Therefore, developing catalytic asymmetric approaches for constructing indole derivatives is highly desirable. In this short review, transition-metal-catalyzed enantioselective synthesis of indoles from 2-alkynylanilines is summarized. 1 Introduction 2 Aminometalation triggered asymmetric cross-coupling reaction/insertion 2.1 Asymmetric Cross-Coupling Reaction 2.2 Asymmetric insertion of C=O, C=C and C≡N bonds 3 Asymmetric relay catalysis 4 Conclusion

Construction of Axially Chiral Styrene-Type Allylamines via Chiral Phosphoric Acid-Catalyzed Asymmetric Reductive Amination

The first enantioselective synthesis of axially chiral styrene-type allylamines was achieved through chiral phosphoric acid mediated atroposelective reductive amination of 1-enal substituted 2-naphthols. This protocol features a broad substrate scope,...

Asymmetric hydrogenation and transfer hydrogenation in the enantioselective synthesis of flavonoids

Asymmetric hydrogenation (AH) and asymmetric transfer hydrogenation (ATH) are versatile synthetic methodologies widely employed in the preparation of chiral compounds. In this review, we explore the applications of AH and...

UV Light-Driven Asymmetric Vinylogous Aldol Reaction of Isatins with 2-Alkylbenzophenones and Enantioselective Synthesis of 3-Hydroxyoxindoles

Chiral 3-hydroxyoxindoles are biologically important molecular motifs which frequently present in natural products and artificial compounds. Herein, we report an ultraviolet light-driven asymmetric vinylogous aldol reaction between versatile isatins and...