Formation of Anionic Trifunctionalized Metallalactones by Nucleophilic Addition at the β-Carbonyl of a Pyruvoyl Ligand

Abstract

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.

Ring Closure of Alkoxycarbonyl(tetracarbonyl)pyruvoyliron Complexes into Metallalactones Induced by Nucleophilic Attack of Carbanions

“…[7] On the other hand, as shown by IR monitoring, 1 reacts very rapidly with carbanionic reagents such as MeLi, nBuLi, NaCH(CO 2 C 2 H 5 ) 2 , NaCH(CϵN) 2 , NaCH[C(O)CH 3 ] 2 , NaCH[C(O)CH 3 ]-(CO 2 CH 3 ), NaCH(CO 2 C 2 H 5 )(CϵN), NaC(CH 3 )(CO 2 -C 2 H 5 ) 2 , or NaC(CH 2 CH=CH 2 )(CO 2 C 2 H 5 ) 2 to afford instantaneously, even at -70°C, new complexes displaying a set of three ν(CϵO) bands between 2084 and 1970 cm -1 . These frequencies are similar to those observed for the product of the reaction between 1 and RO -, RS -, or R 2 P -anions, [13] and are intermediate between the ν(CϵO) of the monofunctionalized anion [Fe(CO) 4 (CO 2 R)]…”

“…This assumption was confirmed by the 13 C NMR spectroscopic data of these compounds. Although most of these complexes were found to be sparingly soluble in organic solvents, the 13 C NMR spectra of these compounds could be obtained in [D 8 ]THF (see Exp.…”

“…Although most of these complexes were found to be sparingly soluble in organic solvents, the 13 C NMR spectra of these compounds could be obtained in [D 8 ]THF (see Exp. Sect.).…”

“…[12] These results prompted us to perform the cyclization of 1 with anionic nucleophiles (RO -, RS -, or R 2 P -). [13] These reactions, as they only afford two isomers of the anionic trifunctionalized metallalactone 3 (Scheme 1, c), also suggested that the formation of the metallalactonic ring could indeed proceed by addition to a terminal carbonyl rather than to the alkoxycarbonyl ligand. However, as the structure of these trifunctionalized anions 3 was not firmly established, we tried to perform analogous reactions using C-H nucleophiles and carbanions of various nucleophilicity and of different steric effects.…”

Addition of nucleophile to bent bonds of the carbonyl group

“…These reactions are of great significance for synthesis [7] and therefore are studied experimentally up to now [9][10][11][12]. Quantum chemical calculations of potential energy surfaces of specific representatives of Ad N 2 processes are also performed and analysed [13][14][15][16][17].…”