Restricted Inversion of Pyramidal Nitrogen through .pi.-Electronic Interaction in an Acyclic System

Design, Synthesis, Characterization, and Biological Activities of Novel Spirooxindole Analogues Containing Hydantoin, Thiohydantoin, Urea, and Thiourea Moieties

On the basis of the scaffolds widely used in drug design, a series of novel spirooxindole derivatives containing hydantoin, thiohydantoin, urea, and thiourea moieties have been designed, synthesized, characterized, and first evaluated for their biological activities. The diastereoselectivity mechanism is proposed, and the systematic conformational analysis is performed. The bioassay results show that the target compounds possess moderate to good antiviral activities against tobacco mosaic virus (TMV), among which compound 22 shows the highest antiviral activity in vitro as well as inactivation, curative, and protection activities in vivo (45 ± 1, 47 ± 3, 50 ± 1, and 51 ± 1%, 500 mg/L, respectively), higher than ribavirin (38 ± 1, 36 ± 1, 38 ± 1, and 36 ± 1%, 500 mg/L, respectively). Thus, compound 22 is a promising candidate for anti-TMV development. Most of these compounds show broad-spectrum fungicidal activities against 14 kinds of phytopathogenic fungi and selective fungicidal activities against Physalospora piricola, Sclerotinia sclerotiorum, and Rhizoctonia cerealis. Additionally, some of these compounds exhibit insecticidal activity against Culex pipiens pallens, Mythimna separata, Helicoverpa armigera, and Pyrausta nubilalis. Compound 17 exhibits the highest larvicidal activity (LC₅₀ was 0.32 mg/L) against C. pipiens pallens.

Chiral arylideneaminoimidazolidin-4-ones: green synthesis and isomerisation mechanism in solution

Arylideneaminoimidazolidin-4-ones synthesized from (l)-α-amino acid via a full green procedure in water (atom economy 91.7% and E-factor 0.09) have been investigated by NMR spectroscopies and DFT calculations, highlighting a development of the species according to an isomerization mechanism.

Base-catalyzed inversion of chiral sulfur centers. A computational study

[reaction: see text] A theoretical study on the pyramidal inversion of the chiral sulfur compounds SO(X)(Me) (X = Cl, OMe, p-MePh) has been carried out by means of the DFT(Becke3LYP) method. Our results reveal that in the case of X = Cl, an organic tertiary amine such as NMe(3) can catalyze the racemization. The base-catalyzed inversion of SO(Cl)(Me) is proposed as a feasible dynamic kinetic resolution mechanism for the synthesis of chiral sulfoxides by the DAG method.