Microwave assisted synthesis of 3,5-disubstituted 1,2,4-oxadiazoles from substituted amidoximes and benzoyl cyanides

Thiol-promoted intermolecular cyclization to synthesize 1,2,4-oxadiazoles including tioxazafen under transition metal-free conditions

“…The methods reported also include the intermolecular cyclization/dehydroaromatization of amidoximes with aldehydes 12 (Scheme 1b). 1,3-Dipolar cycloaddition of nitriles to nitrile oxide 13 is also considered a good choice (Scheme 1c), although some metal catalysts (PtCl 4 and ZnCl 2 ) need to be used. Moreover, the reactions of other coupling partners such as iodobenzene, 14 dithioesters, 15 or gem -dibromomethylarenes 16 with amidoximes have also been realized to fulfill the incessant research leading to 1,2,4-oxadiazoles.…”

Manganese oxide nanoparticles supported on graphene oxide as an efficient nanocatalyst for the synthesis of 1,2,4‐oxadiazoles from aldehydes

“…1,3-Dipolar cycloaddition of nitrile oxides with nitriles [14] and azetine [15] has been reported. The most popular strategy for the synthesis of 1,2,4-oxadiazoles is the O-acylation of amidoximes using activated carboxylic acid derivatives such as benzoyl cyanides, [16] esters, [17,18] anhydrides, [19,20] acid chlorides [21,22] and carboxylic acids, [23] followed by intramolecular cyclodehydration. Another method for the synthesis of 1,2,4-oxadiazole derivatives is the reaction of amidoxime with aldehydes for the synthesis of 4,5-dihydro-1,2,4-oxadiazoles, followed by oxidative dehydrogenation with chemical oxidants [24,25] or electrochemical oxidation methods.…”

1-Adamantylamidoxime

“…Despite this, we found literature articles that report the synthesis of 1-adamantylamidoxime as part of a broader synthetic route, but which only provide a general method for the preparation of amidoximes, without stating differences in terms of the procedure between aliphatic and aromatic ones. Likewise, such reports do not detail yield or physical constant information for this specific product [9,10]. These antecedents highlight an interest both for the development of specific synthetic procedures, allowing for the preparation of aliphatic amidoximes in high yield and for their spectroscopic characterization.…”