In Situ Formation of RSCl/ArSeCl and Their Application to the Synthesis of 4-Chalcogenylisocumarins/Pyrones from o-(1-Alkynyl)benzoates and (Z)-2-Alken-4-ynoates

Abstract

The reaction of diorganyl disulfides or diselenides with PhICl2 in acetonitrile was found for the first time to lead to the in situ formation of organosulfenyl chloride or selenenyl chloride, which enables the regioselective intramolecular chalcogenylacyloxylation of alkynes resulting in the formation of 4-chalcogenylisocumarins/pyrones in good to excellent yields under metal-free conditions.

Construction of 4‐(Methylthio)isochromenones Skeleton through Regioselective Intramolecular Cyclization of 2‐Alkynylbenzoate Mediated by DMSO/[D6]DMSO and SOCl2

“…Among them, the intramolecular cyclization of the 2‐alkynylbenzoates or 2‐alkynylbenzic acids has emerged as an effective and powerful process for the construction of isochromenone framework , . Meanwhile, diverse substituents can be introduced at the 4‐position of the isochromenones , . Although C sp 2 –S bond formation had been widely reported, the preparation of 4‐sulfenylisochromenones has been less explored due to the limitation on their synthetic strategies.…”

“…Ding and co‐workers found that the incorporation of the (trifluoromethyl)thio group into the isochromenone scaffold can be realized through a Lewis acid‐induced electrophilic cyclization of 2‐alkynylbenzoates with trifluoromethanesulfanylamide (Scheme c). Most recently, our own group found that 4‐sulfenylisocoumarins could be readily achieved from the reaction of 2‐alkynylbenzoates with organosulfenyl chloride (RSCl), generated in situ from diorganyl disulfides with PhICl 2 in acetonitrile (Scheme d) . Although these 4‐sulfenylisochromenones with different substitution patterns have been successfully synthesized, there are few reports on the construction of isochromenone skeleton bearing the biological interesting methylthio substituent in its 4‐position , …”

in situ Formation of RSCl/ArSeCl and Their Oxidative Coupling with Enaminone Derivatives Under Transition‐metal Free Conditions

“…[8] Inspired by this work, we are interested to understand whether this one-pot strategy could be applied in the introduction of thio and selenyl functional groups to enaminone and its analogues. [8] Inspired by this work, we are interested to understand whether this one-pot strategy could be applied in the introduction of thio and selenyl functional groups to enaminone and its analogues.…”

“…However, further decrease in the oxidant amount led to a slight drop in the reaction yield (entry 4). Afterward, a series of solvents including DMF, DCM, methanol, THF, and CF 3 CH 2 OH were tested and only DMF provided superior result (entries [5][6][7][8][9]. Conducting the reaction under an ice-bath rather than at room temperature gave similar results (entry 10).…”

“…Recently, we have successfully developed a one-pot protocol to achieve regioselective intramolecular chalcogenylacyloxylation of alkynes which is promoted by in situ generated organosulfenyl chloride (RSCl) or selenenyl chloride (RSeCl). [8] Inspired by this work, we are interested to understand whether this one-pot strategy could be applied in the introduction of thio and selenyl functional groups to enaminone and its analogues. Based on our findings, herein, we report a novel metal-free CÀ H bond functionalization of the enamine compounds to afford the α-chalcogenylenamines in good to excellent yields in the presence of the in situ generated ArSCl or ArSeCl from the reaction between the inactivated disulfides or diselenides and PhICl 2 .…”