Functionalized polysubstituted oxazoles are an important class of five‐membered N,O‐heterocycles that occur widely in the structure of natural products and fine chemicals. They are also often used as building blocks in the synthesis ofheterocyclic molecules with more complex structures. Therefore, efficient synthetic protocols based on Lewis acid promoted reactions are desirable. In this context, we report that, under microwave irradiation, the CeCl3·7H2O/NaI/I2 system is capable of promoting a 5‐exo‐dig cyclization of propargyl amides with good functional group tolerance. The microwave reactor also provides a more convenient and safer method for heating the reaction. This methodology represents a straightforward CeCl3·7H2O/NaI/I2 promoted cyclization using microwave irradiation to accomplish the synthesis of polysubstituted oxazole derivatives.

The benzimidazole core is a common moiety in a large number of natural products and pharmacologically active small molecules. The synthesis of novel benzimidazole derivatives remains a main focus in medicinal research. In continuation of the efforts towards Ce(III) catalysts for organic transformations, we observed for the first time the activity of the iodide ion and copper cation in activating CeCl3·7H2O in the selective formation of prototypical 2-substituted benzimidazoles. The one-pot CeCl3·7H2O-CuI catalytic system procedure includes the cyclo-dehydrogenation of aniline Schiff's bases, generated in situ from the condensation of 1,2-phenylenediamine and aldehydes, followed by the oxidation with iodine, which works as a hydrogen sponge. Mild reaction conditions, good to excellent yields, and clean reactions make the procedure a useful contribution to the synthesis of biologically active fused heterocycles containing benzimidazoquinazolines.

A series of N,P‐ligands were prepared and evaluated in the asymmetric palladium‐catalyzed cycloisomerization of allyl propargyl ether substrates. The reactivity and enantioselectivity of the reaction was shown to be highly dependent on the chiral skeleton of the ligand structures with ee's ranging from 22–99 %. The proton source had a significant impact on the enantioselectivity. The generation of palladium hydride from formic acid led to the highest ee. A selectivity model based on a proposed transition state was used to predict and explain the enantiomeric outcome of the reaction.

The 5‐exo‐dig cyclization of propargylic amides proceeds efficiently in the system CeCl3—NaI—I2 under microwave irradiation to afford polysubstituted oxazoles, e.g. (II) and (IV), in moderate to high yields.