Intramolecular 6-exo-dig Post-Ugi Cyclization of N-Substituted 2-Alkynamides: Direct Access to Functionalized Morpholinone Glycoconjugates

Preparation of pyridopyrazines through tandem Pd-catalyzed C-N/C-C coupling reactions of Ugi adducts

A Pd-catalyzed selective tandem cyclization of the Ugi adduct via Buchwald-Hartwig/C-H bond functionalization reactions has been reported. This sequence offers an interesting approach for synthesizing a wide range of pyrido[1,2-a]pyrazine-3,6-dione scaffolds under mild reaction conditions in moderate to excellent yields. The scope and limitations of the protocol are discussed.

Synthesis, antiproliferative evaluation and in silico studies of a novel steroidal spiro morpholinone

Estrogens play a pivotal role in the development of estrogen-dependent breast cancer and other hormone-dependent disorders. A common strategy to overcome the pathological effects of estrogens is the use of aromatase inhibitors (AIs), which bind to the enzyme and prevent the union with the natural substrate, decreasing the amount of estrogens produced. Several AIs have been developed, including inhibitors with a steroidal backbone and a nitrogen heterocycle in their structure. Encouraged by the notable results presented by current and clinical steroidal drugs, herein we present the synthesis of a steroidal spiro morpholinone derivative as a plausible aromatase inhibitor. The morpholinone derivative was synthesized over a six-step methodology starting from estrone. The title compound and its hydroxychloroacetamide derivative precursor were evaluated for their antiproliferative profile against estrogen-dependent and independent solid tumor cell lines: A549, HBL-100, HeLa, SW1573, T-47D and WiDr. Both compounds exhibited a potent antiproliferative activity in the micromolar range against the six cancer cell lines, with the hydroxychloroacetamide derivative precursor being a more potent inhibitor (GI₅₀ = 0.25-2.4 µM) than the morpholinone derivative (GI₅₀ = 2.0-11 µM). Furthermore, both compounds showed, in almost all cases, better GI₅₀ values than the steroidal anticancer drugs abiraterone and galeterone. Docking simulations of the derivatives were performed in order to explain the experimental biological activity. The results showed interactions with the iron heme (derivative 3) and important residues of the steroidal binding-site (Met374) for the inhibition of human aromatase. A correlation was found between in vitro assays and the score obtained from the molecular docking study.

Sugars in Multicomponent Reactions: A Toolbox for Diversity-Oriented Synthesis

Multicomponent reactions (MCRs) cover strategically employed chemical transformations that incorporate three or more reactants in one pot leading to a functionalized final product. Thus, it is an ideal tool to achieve high levels of complexity, diversity, yields of desired products, atom economy, and reduced reaction times. Sugars belong to the class of naturally occurring compounds with fascinating applications in the field of drug discovery due to the presence of various hydroxy groups and well-defined stereochemistry. However, their potential in MCRs has been realized only recently. This account describes recent advances in the synthesis of sugar-derived heterocycles synthesized by MCRs. We hope to encourage the synthetic and medicinal chemistry community to apply this powerful MCR chemistry to generate novel glycoconjugate challenges.

1 Introduction

2 Synthesis of Various Functionalized Sugar Compounds

2.1 Passerini and Ugi Multicomponent Reactions

2.2 Petasis Reaction

2.3 Hantzsch Reaction

2.4 Domino Ferrier–Povarov Reaction

2.5 Marckwald Reaction

2.6 Groebke–Blackburn–Bienaymé (GBB) Reaction

2.7 Prins–Ritter Reaction

2.8 Debus–Radziszewski Imidazole Synthesis Reaction

2.9 Mannich Reaction

2.10 A3-Coupling Reaction

2.11 [3+2]-Cycloaddition Reactions

2.12 Miscellaneous Reactions

3 Conclusion

Camphorsulfonic Acid-Mediated One-Pot Tandem Consecutive via the Ugi Four-Component Reaction for the Synthesis of Functionalized Indole and 2-Quinolone Derivatives by Switching Solvents

A camphorsulfonic acid-mediated one-pot tandem consecutive approach was developed to synthesize functionalized indole and 2-quinolone derivatives from the Ugi four-component reaction by switching solvents. A reaction of the Ugi adduct in an aprotic solvent undergoes 5-exo-trig cyclization to form an indole ring. In a protic solvent, however, the Ugi adduct undergoes an alkyne-carbonyl metathesis reaction to form a 2-quinolone ring.