Katalytische Ugi-Dreikomponentenreaktion

An Efficient Nickel-Catalyzed Asymmetric Oxazole-Forming Ugi-Type Reaction for the Synthesis of Chiral Aryl-Substituted THIQ Rings

A nickel-catalyzed asymmetric oxazole-forming Ugi reaction of C,N-cyclic azomethine imines and isonitriles is disclosed. The reported protocol proceeds smoothly, and gives the corresponding adducts, which contain two important pharmaceutically active ring-systems (tetrahydroquinoline and oxazole rings), in good yields and excellent enantioselectivities by employing an easily accessible chiral diamine as a ligand. This simple and efficient strategy provides easy access to a series of C1-substituted aryl tetrahydroisoquinolines.

The Enzymology of Organic Transformations: A Survey of Name Reactions in Biological Systems

Chemical reactions that are named in honor of their true, or at least perceived, discoverers are known as "name reactions". This Review is a collection of biological representatives of named chemical reactions. Emphasis is placed on reaction types and catalytic mechanisms that showcase both the chemical diversity in natural product biosynthesis as well as the parallels with synthetic organic chemistry. An attempt has been made, whenever possible, to describe the enzymatic mechanisms of catalysis within the context of their synthetic counterparts and to discuss the mechanistic hypotheses for those reactions that are currently active areas of investigation. This Review has been categorized by reaction type, for example condensation, nucleophilic addition, reduction and oxidation, substitution, carboxylation, radical-mediated, and rearrangements, which are subdivided by name reactions.

Enzymatic Ugi Reaction with Amines and Cyclic Imines

The application of the Ugi reaction to the construction of new peptide scaffolds is an important goal of organic chemistry. To date, there are no examples of the Ugi reaction being performed with a cyclic imine and amine simultaneously. The application of 2-substituted cyclic imines in an enzymatic three-component Ugi-type reaction provides an elegant and attractive synthesis of substituted pyrrolidine and piperidine derivatives in up to 60 % yield. Results on studies of the selection of an enzyme, amount of water, and solvent used in a novel three-component Ugi reaction and the limitations thereof are reported herein. The presented methodology exploiting enzyme promiscuity in the multicomponent reaction fulfills the requirements associated with green chemistry. Several methods, such as isotope labeling and enzyme inhibition, were used to probe the possible mechanism of this complex synthesis. This research is the first example of an enzyme-catalyzed Ugi-type reaction with an imine, amine, and isocyanide.

Three-component asymmetric catalytic Ugi reaction--concinnity from diversity by substrate-mediated catalyst assembly

The first chiral catalyst for the three-component Ugi reaction was identified as a result of a screen of a large set of different BOROX catalysts. The BOROX catalysts were assembled in situ from a chiral biaryl ligand, an amine, water, BH3·SMe2, and an alcohol or phenol. The catalyst screen included 13 different ligands, 12 amines, and 47 alcohols or phenols. The optimal catalyst system (LAP 8-5-47) provided α-amino amides from an aldehyde, a secondary amine, and an isonitrile with excellent asymmetric induction. The catalytically active species is proposed to be an ion pair that consists of the chiral boroxinate anion and an iminium cation.

Efficient copper(II)-catalyzed transamidation of non-activated primary carboxamides and ureas with amines

Amid(e) them all: primary carboxamides and ureas react with aromatic and aliphatic amines in the presence of a copper catalyst to give a wide range of functionalized amides.