Doebner-type pyrazolopyridine carboxylic acids in an Ugi four-component reaction

Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations

By one-pot four- and three-component Ugi reactions involving convertible isocyanides and unexplored pyrrole-containing β-chlorovinylaldehyde, a small library of 20 bisamides with unusual behavior in post-Ugi transformations was prepared and characterized. Surprisingly, a well-documented approach to obtain peptide-containing carboxylic acids through acid hydrolysis of the convertible isocyanide moiety in the Ugi bisamides proceeded in an unexpected manner in our case, leading to the formation of derivatives of amides of heterylidenepyruvic acid. An optimized synthetic protocol for this transformation was elaborated and a plausible sequence involving the elimination of the 2-chloroacetamide moiety and the conversion of the β-chlorovinyl fragment into a vinyl one is provided.

Electrochemical Post-Ugi Cyclization for the Synthesis of Highly Functionalized Spirolactams

The combination of the Ugi reaction and electro-organic synthesis can aid in the creation of novel heterocycles that have not been previously explored. In this study, a new strategy utilizing bis-amides from the Ugi reaction has been developed, which can produce C-S, C-Se, and C-C═O functionalized five-membered spirolactams mediated by electricity under catalyst- and metal-free conditions. Notably, this approach can be applied using a microelectro-flow reactor (μ-EFR) for gram-scale synthesis. The described strategy can synthesize complex azaspiro-fused tricyclic scaffolds with high diastereo- and regioselectivity, highlighting its versatility and potential.

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke-Blackburn-Bienaymé and Ugi reactions

Peptidomimetics with a substituted imidazo[1,2-a]pyridine fragment were synthesized by a tandem of Groebke-Blackburn-Bienaymé and Ugi reactions. The target products contain substituted imidazo[1,2-a]pyridine and peptidomimetic moieties as pharmacophores with four diversity points introduced from readily available starting materials, including scaffold diversity. A small focused compound library of 20 Ugi products was prepared and screened for antibacterial activity.

N-tert-Butyl-2-{2-[2-(4-chloro-phen-yl)-4-hy-droxy-1-(5-methyl-isoxazol-3-yl)-5-oxo-2,5-di-hydro-1H-pyrrol-3-yl]-N-(4-meth-oxy-phen-yl)acetamido}-2-(4-meth-oxy-phen-yl)acetamide methanol monosolvate: single-crystal X-ray diffraction study and Hirshfeld surface analysis

The title compound, C36H37ClN4O7·CH3OH, which crystallizes as a methanol solvate, may possess biological activity, which is inherent for a natural peptide or protein. In the crystal, mol-ecules of the title compound form hydrogen-bonded tetra-mers with the solvate mol-ecules acting as bridges as a result of the O-H⋯O and N-H⋯O inter-molecular hydrogen bonds. Hirshfeld surface analysis was used to study the different types of inter-molecular inter-actions whose contributions are: H⋯H = 53.8%, O⋯H/H⋯O = 19.0%, C⋯H/H⋯C = 14.8%, Cl⋯H/H⋯Cl = 5.3%, N⋯H/H⋯N = 3.2%.