Iodine-catalyzed synthesis of benzoxazoles using catechols, ammonium acetate, and alkenes/alkynes/ketones via C–C and C–O bond cleavage

Zirconium-catalyzed one-pot synthesis of benzoxazoles using reaction of catechols, aldehydes and ammonium acetate

In this study, an efficient method for the synthesis of benzoxazoles by coupling catechols, aldehydes and ammonium acetate using ZrCl4 as catalyst in ethanol is reported. A wide range of benzoxazoles (59 examples) are smoothly produced in high yields (up to 97%). Other advantages of the method include large-scale synthesis and the use of oxygen as an oxidant. The mild reaction conditions allowed late-stage functionalization, facilitating access to several derivatives with biologically relevant structures such as β-lactam and quinoline heterocycles.

I2/DMSO-mediated oxidative C-C and C-heteroatom bond formation: a sustainable approach to chemical synthesis

The I2/DMSO pair has emerged as a versatile, efficient, practical, and eco-friendly catalyst system, playing a significant role as a mild oxidative system, and thus employed as a good alternative to metal catalysts in synthetic chemistry. Presently, I2/DMSO is a thriving catalytic system that is used in preparing C-C and C-X (X = O/S/N/Se/Cl/Br) bonds, resulting in the formation of various bioactive molecules. Many processes utilize this system, including in situ glyoxal synthesis by diverse sp, sp2, and sp3 functionalities via iodination and subsequent Kornblum oxidation. Focusing on oxidation processes, this study examines the synergistic effect of dimethyl sulfoxide (DMSO) and molecular iodine in improving synthetic techniques. We provide a comprehensive overview of the research progress on the I2/DMSO catalytic system for the formation of C-C and C-heteroatom bonds from 2018 to the present. Additionally, the future prospects of this research field are discussed.

One-pot, three-component, iron-catalyzed synthesis of benzimidazoles via domino C-N bond formation

An efficient one-pot, three-component process for the synthesis of benzimidazole derivatives using a catalytic amount of Fe(iii) porphyrin has been developed. The reaction proceeds via domino C-N bond formation and cyclization reactions of benzo-1,2-quinone, aldehydes and ammonium acetate as a nitrogen source to selectively produce benzimidazole. A number of benzimidazole derivatives have been synthesized using this method in high yields under mild reaction conditions.