Azlactones (also known as oxazolones) are heterocycles usually employed in the stereoselective synthesis of α,α-amino acids, heterocycles and natural products. The versatility of the azlactone scaffold arises from the numerous reactive sites, allowing its application in a diversity of transformations. This review aims to cover classical and recent applications of oxazolones, especially those involving stereoselective processes. After a short introduction on their structures and intrinsic reactivities, dynamic kinetic resolution (DKR) processes as well as reactions involving stereoselective formation of a new σ C-C bond, such as alkylation/allylation/arylation, aldol, ene, Michael and Mannich reactions will be exposed. Additionally, cycloadditions, Steglich rearrangement and sulfenylation reactions will also be discussed. Recent developments of the well-known Erlenmeyer azlactones will be described. For the most examples, the proposed mechanism, activation modes and/or key reaction intermediates will be exposed to rationalize both the final product and the observed stereochemistry. Finally, this review gives an overview of the synthetic utility of oxazolones.

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An innovative method for the methylsulfenylation of electrophilic carbons was explored. Cheap and commercially available dimethyl sulfoxide (DMSO) was used as a source of the –SCH3 group. Chalcone, dibenzylideneacetone, and Morita–Baylis–Hillman adduct derivatives were successfully sulfenylated to give the corresponding products in moderate to high yields. Control experiments and DFT calculations revealed deoxygenation of DMSO and nucleophilic addition of a sulfur intermediate as key steps in the entire mechanism.

The Morita-Baylis-Hillman (MBH) reaction has been stablished as an important CÀ C bond-forming transformation between carbonyl-containing compounds and activated olefins. However, the slow reaction rate usually observed with electron-rich electrophilic partners hinders a more widespread use of this reaction. In order to overcome this drawback, the effects of several Brønsted acids on the rate of DABCO-catalyzed MBH reactions were evaluated. The protocol is operationally simple, involving neat and open-flask conditions, and is compatible with a wide range of reagents. We suggest a general acid catalysis mechanism to be responsible for the rate increase. The synthetic versatility of the MBH adducts is exemplified with a two-steps diastereoselective synthesis of the natural product (�)-sitophilure. We hope this acid-mediated protocol to have potential use as a general methodology for the MBH reaction.

Platinum(II) and palladium(II) complexes [ML 2 ] have been isolated from reaction of K 2 PtCl 4 or K 2 PdCl 4 and ligands (L) derived from thiosemicarbazones. The complexes were characterized by elemental analysis, Raman, IR, and NMR spectroscopy. In addition, quantum mechanical calculations were used to predict their structures and spectroscopic properties. For the first time, theoretical calculations using 195 Pt NMR data were used to support the suggested structures. The results indicate that the thionic sulfur and the azomethine nitrogen are bonded to the metal ion in a trans configuration. Antibacterial activities and cytotoxicities of the complexes to B16-F10 and CT26.WT cell lines were also investigated. Some of the complexes demonstrated superior cytotoxic activity compared to cisplatin.

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