Synthesis of Chalcogenylchromenes through Cyclization of Propargylic Aryl Ethers

Abstract

We describe here for the first time the synthesis of 2-(chalcogenyl)-3H-benzo[f]chromenes and the new 3-(phenylselanyl)-2H-chromenes by the radical or electrophilic cyclization of propargylic aryl ethers in the presence of diorganyl diselenides or ditellurides using Oxone as a green oxidant and acetonitrile as solvent in a sealed tube at 100 °C. In this study, thirty-one chalcogenylchromenes with a broad substrate scope were prepared in moderate to excellent yields (50–98%), including compounds derived from natural products.

Design and Synthesis of 1,3‐Diynes as Potent Antifungal Agents against Aspergillus fumigatus

“…After completion of the reaction (TLC), the reaction mixture was evaporated in vacuo to obtain residue which was purified by flash chromatography using a RediSep column (SiO 2 , 12 g) with EtOAc‐petroleum ether mixture as eluent to furnish compound 2 a ‐ e . Spectral data of all the synthesized propargylated phenol were found to be consistent with the previous literature reports [7b,22] …”

Synthesis of 9,10‐Bis(organochalcogenyl)phenanthrenes by Cyclization of (Biphenyl‐2‐alkyne)chalcogenides

“…In addition, a reaction was performed using diphenyl diselenide 2 a and 1,1‐diphenylethylene 11 , affording 12 in 83 % yield (Scheme 5c). These results suggest that this reaction can proceed by both radical [28,29a] and ionic [11d,25] pathways.…”

“…This mixture has a low cost and high stability, making its storage and transport safe [23a] . Our group has pioneered the use of Oxone® in the in situ generation of electrophilic and/or radical organochalcogen species, which were employed in the synthesis of several heterocycles [23c,11d] . The only by‐products in such reactions are non‐toxic KHSO 4 and water.…”

Aqueous sodium tosylate: a sustainable medium for alkylations

“…Significant advances have already been made in the starting materials, as various phenols can be bio-sourced. 1 However, the corresponding alkyl phenyl ethers have been predominantly prepared via Williamson's synthesis-type procedures, which often produce harmful and diverse waste by relying on non-benign solvents 2 and highly toxic alkylating agents, including alkyl halides 3 or dialkyl sulfates. 4 Furthermore, stoichiometric salt quantities are typically generated as by-products 5 requiring direct disposal due to their limited further use.…”