N‐Iodosuccinimide‐promoted Regioselective Selenylation of 4H‐Pyrido‐[1,2‐a]‐pyrimidin‐4‐ones with Diselenides at Room Temperature

Abstract

A novel and efficient approach for the regioselective selenylation of 4H‐pyrido‐[1,2‐a]‐pyrimidin‐4‐ones with diselenides at room temperature has been developed. This procedure is catalyzed by N‐iodosuccinimide under metal‐free conditions with a broad range of substrate scopes and affords C3 selenylation products in good to excellent yields. Furthermore, the sulfenylation with diphenyl disulfides and 4‐methylbenzenethiol in this transformation is successful.

Photoinduced Regioselective Chalcogenation and Thiocyanation of 4H‐Pyrido[1,2‐a] pyrimidin‐4‐ones Under Benign Conditions

“…Based on the above studies and previous literature reports, [12][13][14][15]20] plausible mechanism for chalcogenation and thiocyanation has been proposed (Scheme 7a/b). In the case of sulfenylation and selenylation, the photocatalyst initially absorbs visible light and achieves an excited state (Scheme 7a).…”

“…[12] Recently, same group have also described stoichiometric N-Iodosuccinimide-promoted C-3 selenylation of 4H-Pyrido[1,2-a]pyrimidin-4-ones with diselenides (Scheme 1b). [13] Further, Das et al achieved C-3 chalcogenation of 2-phenyl-4H-pyrido[1,2-a] pyrimidin-4-ones using iodine/ K 2 S 2 O 8 at 70 °C (Scheme 1c). [14] Subsequently, Das group also disclosed stoichiometric [bis(trifluoroacetoxy)iodo]benzene (PIFA) mediated C-3 selenylation with diselenides (Scheme 1d).…”

Electrochemical Oxidative Selenation of 4H‐Pyrido‐[1,2‐a]‐pyrimidin‐4‐ones with Diorganyldiselenides

“…According to previous works [11][12][13]17] and above experiments, a possible mechanism for the electrochemical selenation was outlined in Scheme 4. The first step of the electrochemical selenation is the generation of I 2 or I + by losing two electrons at the surface of graphite anode, which then react with diphenyldiselenide 2 a produce the intermediate IM1.…”

“…In 2021, Wang's group reported an N‐iodosuccinimide (NIS)‐promoted selenylation of 4H‐pyrido‐[1,2‐ a ]‐pyrimidin‐4‐ones to synthesize C 3 ‐selenylated 4H‐pyrido[1,2‐a]pyrimidin‐4‐ones with good yields and wide functional groups tolerance using 3.0 equiv. of diorganyldiselenides as selenium reagent (Scheme 2, a), [11] but equivalent NIS must be used to promote the reaction sufficiently, which did not meet the requirement of atomic economy. Another C 3 ‐selenation mediated by [bis(trifluoroacetoxy)iodo] benzene (PIFA) was reported by Das's group (Scheme 2, b) [12] .…”

4H‐Pyrido[1,2‐a]pyrimidin‐4‐one, biologically important fused heterocyclic scaffold: Synthesis and functionalization

“…In 2021 , Wang et al developed N ‐iodosuccinimide mediated regioselective C3 selenylation of 4 H ‐Pyrido‐[1,2‐ a ]‐pyrimidin‐4‐ones 85 with diselenides 86 at room temperature in dimethyl sulfoxide (Scheme 30) [46]. In the presence of aryl and alkyl selenium compounds, 4 H ‐Pyrido‐[1,2‐ a ]‐pyrimidin‐4‐ones gave an excellent yield of 72–95%, whereas 2‐methyl/2‐aryl‐pyrido‐[1,2‐ a ]‐pyrimidin‐4‐ones gave an excellent yield of 81–97%.…”