Dinotefuran (MTI-446: (RS)-1-methyl-2-nitro-3-(tetrahydro-3-furylmethyl)guanidine) is a new neonicotinoid commercialized by Mitsui Chemicals. Research led to this novel neonicotinoid by the removal of the chloropyridine or chlorothiazole ring that had been considered as indispensable for neonicotinoides. The research advanced as follows; (1) selection of acetylcholine for the lead compound, (2) recognition of the insecticidal advantages of 3-methoxypropyl compounds, (3) synthesis of (+/-)-tetrahydro-3-furylmethyl compounds by cyclization of the 3-methoxypropyl moiety. It resulted in dinotefuran which has a (+/-)-tetrahydro-3-furylmethyl moiety instead of a halogenated aromatic heterocyclic ring, and belongs to the third-generation neonicotinoids (sub-class: furanicotinyl compounds).

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Molecular weight: 202.21 Appearance: colorless crystal Melting point: 107.5°C Vapour pressure: Ͻ1.7ϫ10 Ϫ6 Pa (30°C) Partition coefficient: log P ow ϭϪ0.549 (25°C) Solubility (water): 40 g/l (pH 7, 20°C) Ecotoxicology Avian toxicity Japanese quail (acute oral LD 50): Ͼ2000 mg/kg Mallard duck (acute dietary LD 50): Ͼ1301 mg/kg Aquatic toxicology Carp (96 hr, LD 50): Ͼ100 ppm Daphnia (48 hr, EC 50): Ͼ1000 ppm Alga (72 hr, EC 50): Ͼ100 ppm

Dinotefuran ((RS)-1-methyl-2-nitro-3-(tetrahydro-3-furylmethyl)guanidine) is a new neonicotinoid which has a characteristic (Ϯ)-tetrahydro-3-furylmethyl moiety instead of the pyridine-like moiety of other neonicotinoids. A series of dinotefuran derivatives were synthesized and tested against hemiptera. SAR (structure-activity relationships) of the nitroguanidine part of dinotefuran are summarized as follows: (1) the mono-methyl group as a N-substituent gave the best activity for the acyclic nitroimino and nitromethylene compounds, (2) the acyclic compounds showed the same activity as the cyclic compounds against Nephotettix cincticeps and were superior to them against Laodelphax striatellus, (3) N-acylation of this series scarcely changed the level of activity. On the basis of these results, we selected dinotefuran for development.

The (Ϯ)-tetrahydro-3-furylmethyl moiety, which is a characteristic part of the novel neonicotinoid dinotefuran, was found by research in which acetylcholine was selected as the lead compound. SAR (structure-activity relationships) for the tetrahydrofuran part indicated that the non-substituted moiety showed the highest level of activity, 4-and 5-substituted moieties showed intermediate levels, and 2-and 3-substituted moieties lost the activity. Conformational analysis of these compounds indicated that the substituents changed little the hypothetical active conformation of dinotefuran. Computational analysis proved that dinotefuran, a methoxypropyl compound and other neonicotinoids well overlapped, and dinotefuran adopts the active conformation more easily than the methoxypropyl compound.