2-Diethoxyphosphoryl alcanoic acid dianions (lithium α-lithiocarboxylates) IV. A direct route to 2-fluoro-2-alkenoic acids by the Horner synthesis. Application in the field of pyrethroids

Article abstract of DOI:10.1016/0022-328X(87)85116-1

2-Diethoxyphosphoryl-2-fluoroacetic acid was converted into the lithium α lithiocarboxylate dianion by treatment with n-butyllithium in hexane/tetrahydrofuran at -70 deg C.The Horner reaction between this new dianion and carbonyl compounds gave various 2-fluoro-2alkenoic acids.Application of the method to the cis,trans caronaldehyde ethyl esters led to the 2-fluoroethenyl pyrethroid derivatives (Z-cis, E-cis, Z-trans, E-trans).