PIDA-mediated α-C–H functionalization of enaminones: the synthesis of thiocyano enaminones and chromones in water

Abstract

Herein, an efficient, metal-free process for the α-C–H thiocyanation of enaminones was developed using PhI(OAc)2 as an oxidant at room temperature in an aqueous medium.

Visible Light‐Promoted Selenylation/Cyclization of Enaminones toward the Formation of 3‐Selanyl‐4H‐Chromen‐4‐Ones

“…Among them, the reactions based on the featured chromone annulation of easily available 2‐hydroxyphenyl enaminones have been proved to be the most reliable and broadly applicable one. For example, Zhou's group [8] reported a metal‐free approach to 3‐selenocyanochromone via α‐C−H selenocyanation of enaminones using PhI(OAc) 2 as an oxidant in an aqueous medium (Scheme 1a). Wan's group [9] and Braga's group [10] reported KIO 3 ‐catalyzed synthesis of 3‐selenochromones from 2‐hydroxyphenyl enaminones and diorganyl diselenides, in which using ethyl lactate and glycerol as solvent, respectively (Scheme 1b).…”

Green synthesis of new lawsone enaminones and theirZ/E(CC)-isomerization induced by organic solvent

“…Enaminone derivatives are versatile readily obtainable reagents and their chemistry has received considerable attention in recent years. They have demonstrated a potential as multipurpose synthetic intermediates in organic synthesis such as various heterocyclic compounds, [1][2][3][4][5] synthons for the synthesis of various biologically active compounds such as antitumor, anti-epileptic, anti-inammatory, antibacterial, anticonvulsant, and other therapeutic agents [6][7][8][9][10][11][12][13] and also a substructure that frequently occurs in natural products. 14 They can also be used as starting materials for the stereoselective preparation of g-aminoalcohols (by reduction).…”

Recent Advances in Organic Synthesis Based on N,N-Dimethyl Enaminones

“…8 Interestingly, when Ru(bpy) 3 Cl 2 •6H 2 O was employed as the photoredox catalyst, the -thiocyanation reaction provided NH 2 -functionalized thiocyanated enamines through a further amino-exchange process. Shortly afterwards, Zhou and co-workers disclosed a similar -thiocyanation of N,N-dimethyl enaminones in the presence of KSCN using an undivided cell under electrolytic conditions 9 or with PhI(OAc) 2 as an oxidant, 10 respectively. These -thiocyanation reactions were proved to occur via a free-radical pathway.…”

“…In 2019, Zhou and co-workers reported the synthesis of 3-thiocyanyl chromones via both electrochemistry-induced thiocyanation of N,N-dimethyl enaminones using an undivided electrolytic cell and PIDA-mediated thiocyanation of enaminones in water at room temperature (Scheme 62). 9,10 Nevertheless, these two reaction processes involved the addition of a thiocyanyl free radical to the enaminone under the different oxidative conditions. Furthermore, various thiocyanyl chromones could be obtained in good to excellent yields with diverse functional groups using these protocols.…”