Copper‐Catalyzed Three‐Component Reaction of Oxadiazoles, Elemental Se/S and Aryl Iodides: Synthesis of Chalcogenyl (Se/S)‐Oxadiazoles

Abstract

An efficient copper‐catalyzed three‐component chalcogenation of oxadiazoles with elemental selenium/sulfur and aryl iodide is described herein. This one‐pot C(sp2)‐H bond chalcogenation approach is attractive and practical, since a cheap copper catalyst is employed with minimum catalytic loading, in an open‐to‐air atmosphere. Under optimized conditions, that reaction provides a wide range of structurally diverse organochalcogenyl (Se/S)‐oxadiazoles in good to excellent yields with good functional group tolerance. This practical approach represents a valuable contribution to synthetic and medicinal chemistry, providing an important addition to the current C−Se/S bond formation chemistry scenario.

Copper-catalyzed direct C–H arylselenation of 4-nitro-pyrazoles and other heterocycles with selenium powder and aryl iodides. Access to unsymmetrical heteroaryl selenides

“…Since the reaction is not proceeding without base (Table 1, entries 3, 5 and 12) it is safe to assume that the selenium enters the catalytic cycle in a form of a selenide anion (Se 2À ) 61,62 or diselenide anion (Se 2 2À ). 57 The reduction of elemental selenium with base is a well known process. The rst step in the catalytic cycle involving copper is oxidative addition of Cu (I) halide into the I-C Ar bond of the phenyl iodide, forming Cu (III) intermediate A.…”

“…60 2-(2-Bromophenyl)imidazo[1,2-a]pyridines were also explored as starting materials in an intramolecular variant of the reaction by Wang et al 58 In another paper, Wu et al proposed conditions for C-H arylselenation of 2-phenyl-and 2-aryl-1,3,4-oxadiazoles, 62 a scaffold found in many drugs. 79 Slightly different conditions for the same starting materials were also selected by Braga et al 57 Since we have our long-standing interest in TM-catalyzed C-H activation, we were curious if a general, practical and concise approach could be realized for the arylselenation of other heterocycleswidening the scope of the starting materials. The regioselectivity of C-H activation reactions of more complex functionalized substrates containing two or more reactive C-H bonds is an important topic of current research.…”

Borophosphate glass as an active media for CuO nanoparticle growth: an efficient catalyst for selenylation of oxadiazoles and application in redox reactions

“…Based on previous reports [27][28][29] , a plausible mechanism can be proposed (Scheme 3). In the presence of base, selenium generated selenolate or diselenolate anions 48,49 .…”

“…It is used in pharmaceuticals and considered a "privileged structure" [23][24][25][26] . Considering the biological relevance of organoselenides and the therapeutic properties of ODZs, few methods are available to access selenylated ODZs [27][28][29][30] .…”

Synthesis of Novel Selenocyanates and Evaluation of Their Effect in Cultured Mouse Neurons Submitted to Oxidative Stress

“…By considering the biological roles of these compounds, development of new and efficient routes for the synthesis of organoselenides is a tempting research area [12,24,25]. Therefore, as an additional step of the ongoing efforts aiming the design of novel organoselenides and medicinal chemistry [26][27][28], present study reports the synthesis of novel aromatic selenocyanates, comprising a second generation of chalcogenide esters. Furthermore, assessment of the effect of these compounds on the oxidative challenge elicited by hydrogen peroxide (H2O2) in mixed cultures of mouse neurons was undertaken, in order to provide insightful cues on their biological activity.…”