Novel phosphate anthelmintics. 3. Alkyl and aryl 1-methyleneallyl phosphates, phosphonates, and phosphinates

A series of new highly chlorinated 1-methyleneallyl ("butadienyl") dialkyl phosphates and related phosphonates and phosphinates has been synthesized and assessed for anthelmintic activity in mice against the tapeworm Hymenolepis nana and the pinworm Syphacia obvelata. Highest activity was observed with diethyl 2,3,3-trichloro-1-dichloromethyleneallyl ("perchlorobutadienyl") phosphate (14), while replacement of both ethoxy groups by methoxy and larger alkoxy or phenyl groups gave less efficacious compounds. In general, chlorine depletion of the 1,3-butadien-2-yl moiety or saturation of one double bond reduced anthelmintic responses.