Two distinct protocols for the synthesis of unsymmetrical 3,4-disubstituted maleimides based on transition-metal catalysts

Two tandem catalytic systems are described for the synthesis of novel 3,4-disubstituted maleimides using the same Ugi adducts as starting materials. 4-Aryl-3-pyrrolyl- and 4-aryl-3-indolyl-maleimides were successfully obtained via a Pd(OAc)2/PPh3 based protocol. In contrast, maleimide-fused pyrrolo and indolo[1,2-a]quinolines were obtained in a complementary methodology using CuI/L-proline. These strategies involved a combination of benzylic amine oxidation, trans-amidation, intramolecular Knoevenagel condensation, and N-arylation reactions. Computational investigations provide further insights into this reaction sequence.

Transition Metal-Free N-S Bond Cleavage and C-N Bond Activation of Ugi-Adducts for Rapid Preparation of Primary Amides and α-Ketoamides

A novel method of transition metal-free N-S bond cleavage and subsequent C-N bond activation of Ugi-adducts was developed. Diverse primary amides and α-ketoamides were prepared in a rapid, step-economical and highly efficient manner in two steps. This strategy features excellent chemoselectivity, high yield and functional-group tolerance. Primary amides derived from the pharmaceuticals probenecid and febuxostat were prepared. This method opens a new pathway for the simultaneous synthesis of primary amides and α-ketoamides in an environmentally friendly manner.

Discovery of 2,3-dihydro-1H-pyrrolo[3,4-b]quinolin-1-one derivatives as possible antileishmanial agents

A series of uniquely functionalized 2,3,-dihydro-1H-pyyrolo[3,4-b]quinolin-1-one derivatives were synthesized in one to two steps by utlilizing post-Ugi modification strategy and were evaluated for antileishmanial efficacy against visceral leishmaniasis (VL). Among...

Diversification of α-ketoamides via transamidation reactions with alkyl and benzyl amines at room temperature

A wide range of N-tosyl α-ketoamides underwent transamidation with various alkyl amines in the absence of a catalyst, base, or additive. On the other hand, transamidation in N-Boc α-ketoamides was achieved in the presence of Cs₂CO₃. The reactions proceeded at room temperature and provided good to excellent yields of transamidation products under the optimized conditions. Broad substrate scope, functional group tolerance and quick conversions are the important features of the developed methodology.

Pyridine-Enabled C-N Bond Activation for the Rapid Construction of Amides and 4-Pyridylglyoxamides by Cooperative Palladium/Copper Catalysis

A pyridine-enabled C-N bond activation of peptidomimetics employing cooperative palladium/copper catalysis in water is developed. Diverse amides and 4-pyridylglyoxamides are simultaneously synthesized through two steps from commercially available materials in a rapid, environmentally friendly, and high atom-economical manner.