Publications by authors named "Edson Barrera"

A short, efficient, and stereoselective methodology is described for the synthesis of 5-((dimethylamino)methylene)hydantoins and their conversion into oxoaplysinopsins and parabanic acids. A highly convergent one-pot, two-step reaction between methyl -arylglycinates, isocyanates, and DMFDMA under microwave irradiation provided the corresponding (dimethylamino)methylene hydantoins as a single -stereoisomer in high overall yields. The synthesis of ()-1-(1-phenylethyl) chiral hydantoins, which undergo a stereoselective addition of acetic anhydride, aza-heterocycles, and amines, received special attention.

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The increase in multi-drug resistant strains has caused a sharp rise in life-threatening fungal infections in immunosuppressed patients, including those with SARS-CoV-2. Novel antifungal drugs are needed to combat multi-drug-resistant yeasts. This study aimed to synthesize a new series of 2-oxazolines and evaluate the ligands in vitro for the inhibition of six species and in silico for affinity to the CYP51 enzymes (obtained with molecular modeling and protein homology) of the same species.

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As a new approach, pyrrolo[1,2-]pyrazines were synthesized through the cyclization of 2-formylpyrrole-based enaminones in the presence of ammonium acetate. The enaminones were prepared with a straightforward method, reacting the corresponding alkyl 2-(2-formyl-1-pyrrol-1-yl)acetates, 2-(2-formyl-1-pyrrol-1-yl)acetonitrile, and 2-(2-formyl-1-pyrrol-1-yl)acetophenones with DMFDMA. Analogous enaminones elaborated from alkyl ()-3-(1-pyrrol-2-yl)acrylates were treated with a Lewis acid to afford indolizines.

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Palladium-catalyzed functionalization was presently performed on two building blocks: 4-oxazolin-2-ones and 4-methylene-2-oxazolidinones. Direct Heck arylation of 4-oxazolin-2-ones led to a series of 5-aryl-4-oxazolin-2-ones, including analogues with N-chiral auxiliary, in an almost quantitative yield. The Pd(II)-catalyzed homocoupling reaction of 4-oxazolin-2-ones provided novel heterocyclic across-ring dienes.

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Article Synopsis
  • - The study focuses on using enantiopure 3-((R)- and 3-((S)-1-phenylethyl)-4-oxazoline-2-ones as chiral building blocks to create diverse heterocycles featuring stereogenic quaternary centers.
  • - N-(R)- or N-(S)-1-phenylethyl groups act as effective chiral auxiliaries, enhancing asymmetric induction at specific positions in the oxazolin-2-one ring, leading to various adducts through thermal and microwave-promoted reactions.
  • - The resulting products, which can include fused six-membered rings and highly substituted cyclic carbamates, depend on the choice of electrophiles and reaction conditions
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