Oxadiazolone ring

Construction of the oxadiazolone ring from the aforementioned hydrazine is illustrated below ... 

Recently, another important class of chemicals based on the oxadiazolone ring have shown activity similar to the carbamates, but with surprising activity on carbamate-resistant green rice leafhopper (Structure, Table 2) (11-13). To Investigate the resistance mechanism in green rice leafhopper, we decided to explore the structure-activity relations of both insecticide classes against AChE preparations from susceptible and resistant insects. The difference in the substituent effects was expected to provide critical information at the molecular level of the receptor complex. 

Nitrilimines (621) are another class of 1,3-dipoles which provide a useful entry into the pyrazole ring. They are often generated by cycloreversion (79AG(E)72l) of tetrazoles, triazolopyridines and oxadiazolones (79JOC2957) (Scheme 55). Pyrazolines of known stereochemistry, pyrazoles and indazoles (Section 4.04.3.1.1(iii)) have all been prepared from nitrilimines. 

Reaction of diazocine 190 (see Section II,A,3) with phosgene afforded the oxadiazolone derivative 191 (79CPB2608). As mentioned earlier (see Section II,B,1), annelated diazocine 51 accompanied 50 (R = R1 = H) as a product of the Schmidt reaction of 1,3-cyclohexanedione. It was postulated, on the basis of ring-opened hydrolysis products (see Section IV,D), that 51 arose from annelation of 50 (R = R1 = H). [A 1,4-diazo-cinedione and its annelation product were also obtained (89AHC185), but it was determined that in this case annelation occurred at the intermediate seven-membered p-ketolactam stage, not on the diazocine that followed.]... 

Effect of Ring Substituents at 4-Position on the Toxicity of Dihydrobenzofuranyl Oxadiazolones... 

Pymetrozine (1), a pyridine azomethine, was synthesized for the first time at the end of 1986 [3, 5]. The concept behind this discovery was primarily chemically directed with, however, a strong rational element [2j. In a first step ring transformations of 1,3,4 oxadiazolon-3-yl ketones 2 with N-nucleophiles were investigated, leading to numerous new five- and six-membered N-amino heterocydes,... 

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