We highlight the recent advances of the Ugi reaction in the last two decades from 2000–2019, mainly in the synthesis of linear or cyclic peptides, heterocyclic compounds with versatile ring sizes, and natural products, as well as the enantioselective Ugi reactions.

The metabolism and polarity of the all-cis tetra-fluorocyclohexane motif is explored in the context of its potential as a motif for inclusion in drug discovery programmes. Biotransformations of phenyl all-cis tetra-, tri- and di- fluoro cyclohexanes with the human metabolism model organism Cunninghamella elegans illustrates various hydroxylated products, but limited to benzylic hydroxylation for the phenyl all-cis tetrafluorocyclohexyl ring system. Evaluation of the lipophilicities (log P) indicates a significant and progressive increase in polarity with increasing fluorination on the cyclohexane ring system. Molecular dynamics simulations indicate that water associates much more closely with the hydrogen face of these Janus face cyclohexyl rings than the fluorine face owing to enhanced hydrogen bonding interactions with the polarised hydrogens and water.

Herein, a novel sandwich-like α-ketoglutaric acid Schiff base-aminated chitosan composite (α-kGl-AmCsSB) was fabricated by reacting α-ketoglutaric acid and aminated chitosan. The as-fabricated α-kGl-AmCsSB was inspected by diversified characterization tools to determine its morphology, surface charge, and chemical composition as well as define the linkage pathway between α-kGl and AmCs. The SEM images demonstrated a spongy network of AmCs with interconnected pores structure which turned to a quite rough surface due to the linkage of α-kGl to the free amine groups of AmCs. Notably, the XPS and FTIR spectra suggested the linkage of α-kGl to the amine group of AmCs. The experimental results implied the superior adsorption efficiency of Congo red (CR) onto α-kGl-AmCsSB since the maximum adsorption capacity (q_max) reached 434.78 mg/g at 25 °C and pH 3. Based on kinetics data, the adsorption of CR on α-kGl-AmCsSB followed pseudo-second-order model. Furthermore, D-R model infers that the CR adsorption onto α-kGl-AmCsSB occurred via physical interactions since the E value < 8 kJ/mol. The recyclability test was implemented for five cycles with R% > 72%. More importantly, the adsorption mechanism of CR onto α-kGl-AmCsSB was proposed and discussed. Ultimately, the novel sandwich-like α-kGl-AmCsSB exhibited advanced adsorption performance toward CR along with excellent reusability. Based on these results, we recommend more modifications on α-kGl-AmCsSB for exploiting its remarkable advantages and applying it on a large scale.