Syntheses and Biological Activities of Some Dithiolanylidenemalonate Derivatives and Related Compounds

Abstract

Several dithiolane derivatives are known as agrochemicals and natural products with a variety of agrochemically interesting activities (Maekawa, 1985; Taninaka, 1985). They include fungicide, (isoprothiolane: diisopropyl 1,3-dithiolan-Z-ylidenemalonate, la), insecticide (phosfolan: 2-(diethoxyphosphinylimino)-1,3-dithiolane), acaricide -fungicide (quinomethionate: 6-methyl-1,3-dithiolo (4,5-j quinoxaline-2-one), acetylcholine antagonist (nereistoxin: 4-dimethylamino-1,2-dithiolane), and plant growth retardant (asparagusic acid: 1,2-dithiolane-4-carboxylic acid). Many ketene dithioacetals including isoprothiolane have been synthesized and evaluated for pesticides (Taninaka, 1978; Taninaka et al., 1976). Intending to increase the plant systemic activity in dithiolane fungicides, we tried to modify the structure of isoprothiolane. Since there is a tendency that alcohols, acids, amides, hydrazides and ureas appear to move rather readily in symplast or apoplast (Wakabayashi, 1985), structure modifications were mainly performed 1) on the dithiolane ring to introduce a hydroxyl group followed by acylation to protect it and 2) on the malonate ester group to transform into amide, hydrazide or urea derivatives.