Neonicotinoids nitro group

Regarding the structural features of neonicotinoids, the pharmacophore part is characterized by a polar group represented by eidier a nitro group or a cyano group 13). Based on neighboring structural differences in the pharmacophore and on the heterocycle that typically is aromatic and mono-substituted by chlorine, neonicotinoids can be grouped as presented in Table II. 

II). Thus the 7t-conjugated system composed of a N-nitro-imino- or N-cyano-imino group and the conjugated nitrogen in 1-position are considered essential moieties for the binding of neonicotinoids to the putative cationic subsite in insect nAChR. 

The discovery of the N-nitroguanidine dinotefiiran (4, 2002, Mitsui Chemicals) [58, 59], resulted from the idea of incorporating an N-nitro-imino group into the ACh structure as lead compound [60]. After synthesis of neonicotinoids containing a N-(3-methoxy-propyl) moiety (hydrogen acceptor site) the investigation of cyclic ether groups led to the discovery of the novel THF moiety, which shows a more than ten-fold increase of insecticidal activity. 

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