Reactions of nucleophiles with cyclopentadienyliron complexed halotoluenes

Abstract

η 6- o-Chlorotoluene-η 5-cyclopentadienyliron hexafluorophosphate undergoes nucleophilic substitution of the chlorine atom with anions generated (K 2CO 3/DMF) from methyl thioglycolate, diethyl malonate, dimethyl malonate, methyl acetoacetate and 2,4-pentanedione. The compounds prepared were o-CH 3C 6H 4SCH 2CO 2CH 3FeCp +PF 6 −, o-CH 3C 6H 4CH(CO 2C 2H 5) 2FeCp +PF 6 −, o-CH 3C 6H 4CH(CO 2CH 3) 2FeCp +PF 6 −, o-CH 3C 6H 4CH(COCH 3)CO 2CH 3FeCp +PF 6 − and o-CH 3C 6H 4CH 2COCH 3FeCp +PF 6t̄. Similarly, the reaction of diethyl malonate, dimethyl malonate, methyl acetoacetate anions and methylamine with η 6-2,6-dichlorotoluene-η 5-cyclopentadienyliron hexafluorophosphate yielded monosubstitution of one of the chloro groups. The complexes prepared in this study were η 6-diethyl(3-chloro-2-methyl) phenylmalonate- η 5-cyclopentadienyliron hexafluorophosphate, η 6-dimethyl(3-chloro-2-methyl)phenylmalonate-η 5-cyclopentadienyliron hexafluorophosphate, η 6-methyl(3-chloro-2-methyl)phenylacetoacetate-η 5-cyclopentadienyliron hexafluorophosphate and η 6-3-chloro(2-methyl-N-methyl)aniline-η 5-cyclopentadienyliron hexafluorophosphate. Reaction of η 6-2,6-dichlorotoluene-η 5-cyclopentadienyliron hexafluorophosphate with excess methanol as well as methyl thioglycolate in the presence of K 2CO 3 resulted in disubstitution of both chloro groups to yield new complexes, η 6-2,6-dimethoxytoluene-η 5-cyclopentadienyliron hexafluorophosphate and η 6-methyl[(2-methylphenyl)1,3-dithio] diacetate-η 55-cyclopentadienyliron hexafluorophosphate, respectively. Complexes o-CH 3C 6H 4CH(CO 2C 2H 5) 2FeCp +PF 6 −, o-CH 3C 6H 4CH(CO 2CH 3) 2FeCp +PF 6 − and o-CH 3C 6H 4CH 2 COCH 3FeCp + PF 6 − react with excess K 2CO 3 and benzyl bromide in refluxing methylene chloride to give 80–90% yields of complexes o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2C 2H 5) 2FeCp +PF 6 −, o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2CH 3) 2FeCp +PF 6 − and o-CH 3C 6H 4CH(CH 2C 6H 5)COCH 3FeCp +PF 6 −, respectively. Reaction of complex, o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2C 2H 5) 2FeCp +PF 6 − with one molar equivalent of t-BuOK followed by acidic work-up gives o-(C 2H 5CO 2CH 2)C 6H 4CH(CO 2C 2H 5)CH 2C 6H 5FeCp +PF 6 −. Similarly, reactions of complexes o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2C 2H 5) 2FeCp +PF 6 − and o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2CH 3) 2FeCp +PF 6 − with t-BuOK in THF followed by alkylation with methyl iodide gave the new complexes, o-(C 2H 5O 2C(CH 3)CH)C 6H 4CH(CH 2C 6H 5)CO 2C 2H 5FeCp +PF 6 − and o-(CH 3O 2C(CH 3)CH)C 6H 4CH(CH 2C 6H 5)CO 2CH 3FeCp +PF 6 −, respectively. Vacuum sublimation of the new complexes, o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2C 2H 5) 2FeCp +PF 6 − and o-(C 2H 5O 2CCH 2)C 6H 4CH(CH 2C 6H 5)CO 2C 2H 5FeCp +PF 6 − gives o-CH 3C 6H 4C(CH 2C 6H 5)(CO 2C 2H 5) 2 and O-(C 2H 5O 2CCH 2)C 6H 4CH(CH 2C 6H 5)CO 2C 2H 5, respectively.