Anionic nucleophilic reagents Nu -) CH 3 O -, C 2 H 5 O -, t-BuO -, CH 3 S -, and P(C 6 H 5 ) 2were found to react with (CO) 4 Fe(CO 2 CH 3 )[C(O)C(O)CH 3 ] to afford two isomers of anionic trifunctionalized metallalactones, {(CO) 3 Fe[C(O)C(CH 3 )(Nu)OC(O)](CO 2 CH 3 )} -, whose formation resulted from an addition of the nucleophile to the β carbonyl of the pyruvoyl ligand. In this reaction, the metallacycle formation was found to occur by a further addition of the oxygen of the same β carbonyl on a terminal carbonyl. In acidic medium, these anionic complexes evolved into neutral metallalactones (CO) 4 Fe[C(O)C(CH 3 )(Nu)OC(O)] already obtained by performing the same reaction with pronucleophiles (Nu-H type reagents). Achievement of (CO) 4 Fe[C(O)C(dCH 2 )OC(O)] when the reaction was performed with t-BuOcould result from an intermediate formation of the enolate form of the pyruvoyl ligand [Fe]-C(O)-C(dCH 2 )-Ounder basic conditions.
Reactions of primary amines with the perfluorovinyl complex [{Fe(CO)3}2{p-C(SMe)(CF3)CCF2}] 1 proceed with cleavage of two C-F bonds to give 2, whereas with secondary amines fluorine migration and C-F bond rupture afford the novel organometallic complex 3; both 2 and 3 have been characterized by X-ray analysis.
International audienceThe reaction of carbanions with the pyruvoyl-substituted iron complex [(CO)4Fe(CO2CH3){C(O)C(O)CH3}] (1) affords the anionic trifunctionalized metallalactones [(CO)3Fe{C(O)C(CH3)(CRR′R″)OC4(O)(Fe–C4)}(CO2CH3)]– (3), whose formation results from the addition of the nucleophile to the β carbonyl of the pyruvoyl moiety, followed by attack of the oxygen of this β carbonyl on a terminal carbonyl ligand. These anionic lactones react, at low temperature, with HCl to give rise to the neutral lactones [(CO)4Fe{C(O)C(CH3)(CRR′R″)OC4(O)(Fe–C4)}] (2), which were previously obtained by addition of NuH nucleophiles to 1. Complex 3(3), whose lactonic ring formation has been performed using the diethyl malonate anion (R = R′ = CO2C2H5; R″ = H), and the dimethyl-substituted neutral lactone 2(1) (R = R′ = R″ = H) have been characterized by X-ray diffraction studie
The reactions between alcohols ROH (R = Me, Et) and RR(OH)2 (RR = CH2−CH2) and the [perfluoro(sulfanyl)vinyl]diiron complex [{Fe(CO)3}2{µ‐C(SMe)(CF3)CβCαF2}] (1) in THF at room temperature involve substitution at the Cα atom to give new (alkoxymethylene)thiaferracyclobutadiene compounds [{Fe(CO)3}2{µ‐S(Me)C(CF3)CβCα(OR)2}] [R = Me (2a), Et (2b); RR = CH2CH2 (2c)]. Treatment of 1 with aniline and (methoxycarbonyl)hydrazine, bases of intermediate strength according to Pearson, produces α,β‐substituted thiaferracyclopentadiene [{Fe(CO)3}2{µ‐S(Me)C(CF3)Cβ(NHR)Cα(NHR)}] [R = Ph (5a), NHC(O)OMe (5b)] complexes. It is suggested that these compounds form through initial nucleophilic attack at Cα to give the zwitterionic intermediate [{Fe(CO)3}2{µ‐S(Me)C(CF3)CC(NRH)2}] (f). Thermally induced C−F bond activation is a feature of these reactions. When 1 reacts with thioamides containing three “hard” competitive primary and secondary amine functions and one “soft” thione function, the nucleophile first attacks at Cα through a secondary amine and, in a second step, at Cβ through the thiol function to give α,β adducts [{Fe(CO)3}2{µ‐S(Me)C(CF3)CβSC(=NR2)N(R1)Cα(Cβ−Cα)] [R1 = NH2, R2 = CH3 (6a); R1 = CH3, R2 = H (6b); R1 = R2 = CH3 (6c)] possessing novel iminothiazolidine systems fused to the five‐membered metallacyclic ring. Treatment of 1 with acetylhydrazine, which has three “hard” nucleophilic functions, results in the formation of the compound [{Fe(CO)3}2{µ‐S(Me)C(CF3)C(H)C(10)NNC(Me)O(C(10)−O)}] (7a), in which an oxadiazole function is fused to the thiaazaferracyclohexene ring. The position of the fluorine substituent on the CαCβCγ(CF3)S(Me) ring of ferracyclopentadiene complexes has been found to be the essential factor determining the specific activation of the C−F bond. A single fluoro substituent attached to the β‐carbon atom of the chain can be activated by nucleophiles to give α,β adducts [{Fe(CO)3}2{µ‐S(Me)C(CF3)Cβ(X)Cα(NRR′)}] [X = OR′′, R = R′ = R′′ = Me (3a); X = OR′′, R = R′′ = Me, R′′ = C(O)NMe2 (3b); X = SR′′ (4)]. In contrast, complexes in which a single fluorine atom is linked to the α‐carbon atom do not undergo C−F bond cleavage reactions. X‐ray structures of compounds 2a, 3b, 5a, 5b, 6a and 7a are reported.
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