Metal-free synthesis of 3-chalcogenyl chromones from alkynyl aryl ketones and diorganyl diselenides/disulfides mediated by PIFA

Abstract

3-Selenyl/sulfenyl chromones/thiochromones were conveniently synthesized from the PIFA-mediated reactions between alkynyl aryl ketones bearing an ortho-methoxy/methylthio group and diorganyl diselenides/disulfides. This metal-free approach is postulated to first undergo the formation...

Synthesis of 4‐Chalcogenylated Isoxazoles Mediated by PhICl2 and Diorganyl Disulfides/Diselenides

“…In our recent work, by using diselenides/disulfides as selenium and sulfur sources, we realized the synthesis of 4‐chalcogenylisocumarins [18] and 3‐chalcogenylchromones [19] via cascade annulation/organochalcogenylation mediated by hypervalent iodine reagents, i. e., (dichloroiodo)benzene (PhICl 2 ) and phenyliodine bis(trifluoroacetate) (PIFA). In continuation of our research on synthesis of various chalcogenylated heterocycles, we are interested at investigating whether the above protocol could be applied to the synthesis of the biologically interesting 4‐chalcogenylated isoxazoles.…”

“…of PhICl 2 in acetonitrile (CH 3 CN) was stirred at room temperature for 30 min (entry 1, Table 1). Inspired by our another work describing the synthesis of 3‐chalcogenylchromones via PIFA‐promoted tandem chalcogenylation and cyclization of alkynyl aryl ketones, [19] we also attested the efficacy of phenyliodine diacetate (PIDA) and PIFA. However, the results showed that PIDA was ineffective and PIFA only led to the formation of product in trace amount (entries 2 and 3, Table 1), mainly because PIDA was less active for the reaction with 90% starting material recovered and PIFA was so potent for the transformation to give a complex mixture.…”

“…Based on the previous reports [18][19] describing the organochalcogenylation of alkynyl derivatives, a possible mechanism for this PhICl 2 /diselenides or disulfides-mediated intramolecular electrophilic cyclization of alkynone Z-O-methyloximes is postulated (Scheme 4). First, R 3 SeSeR 3 reacts with PhICl 2 to generate the complex I, [18] which is smoothly converted to intermediate II via the nucleophilic attack of a chloride anion onto the selenium center with concomitant elimination of PhI.…”

Visible-Light-Promoted Transition-Metal-Free Construction of 3-Perfluoroalkylated Thioflavones

“…Huang’s group realized the reaction of AgSCF 3 with methylthiolated alkynones for the synthesis of 3-trifluoromethylthiolated thioflavones with (NH 4 ) 2 S 2 O 8 as the oxidant at 80°C ( Wang L. et al, 2021 ). Du and Zhao et al reported the synthesis of selenyl/sulfenyl thioflavones with phenyliodine(III) bis(trifluoroacetate) (PIFA) as an oxidant ( Ai et al, 2020 ). Recently, Ye and Wu’s group realized an Ir-photocatalyzed radical relay reaction of methylthiolated alkynones and potassium metabisulfite in the presence of sodium methylsulfinate ( Liu et al, 2022 ).…”

[Bis(trifluoroacetoxy)iodo]benzene Mediated C‐3 Selenylation of Pyrido[1,2‐a]Pyrimidin‐4‐Ones Under Ambient Conditions

“…Very recently, Du and Zhao et al . reported a regioselective cyclization of alkynyl aryl ketones mediated by PIFA [Bis(trifluoroacetoxy)iodo]benzene in the presence of organochalcogenides, affording several structurally diverse 3‐chalcogenyl chromones in reasonable yields [11b] …”