A Method for the Synthesis of Carbene Precursors from Aldehydes and the Metalates (η⁵-C₅H₅)(CO)₂Fe^- and (η⁵-C₉H₇)(CO)₂Fe^-

Abstract

Nucleophilic addition of the metalate Cp(CO)2Fe-M+ (M = Na, K) to aldehydes RCHO (R = Ph, CH3, p-OCH3Ph, p-ClPh, p-CH3Ph, p-CF3Ph, o-OCH3Ph, and CHC(CH3)2) and subsequent capture with ClSi(CH3)3 provided the (α-siloxyalkyl)iron complexes Cp(CO)2FeCH(OSiMe3)R in 42−79% yield. This new reaction was extended to the indenyl-ligated metalate In(CO)2Fe-Na+ with several aldehydes RCHO (R = Ph, CH3, p-OCH3Ph). Treatment of the (α-siloxyalkyl)iron complexes with trimethylsilyl triflate at between −25 and −78 °C, in the presence of alkenes, gave cyclopropanes through iron carbene complexes.

Reduction and Condensation of Aldehydes by the Isolated Cofactor of Nitrogenase

“…The newly discovered reactivity of the isolated cofactor toward aldehydes provided a platform for us to use isotope labeling experiments to probe the mechanism of cofactor-based aldehyde reduction. The first question we asked was whether activation of formaldehyde (CH 2 O) would result in a cluster-bound hydroxymethyl intermediate via several plausible routes. − Should this be the case, the hydroxymethyl species would need to undergo a series of proton/electron transfer steps, coupled with removal of oxygen as water, to generate CH 4 that contains two substrate-derived hydrogens and two solution-derived hydrogens (Figure A). To test our hypothesis, we monitored the amount of H/D labels in product CH 4 when CH 2 O and CD 2 O were supplied as the respective substrates to D 2 O- and H 2 O-based reactions (Figure A, ①, ②).…”

Recent chemistry of the η5-cyclopentadienyl dicarbonyl iron anion

“…The method has been applied in the synthesis of a precursor for cilastatin [242]. The resultant chiral Fp + carbene is reacted in the presence of a suitable substituted olefin to generate the desired chiral cis cyclopropane [243,244]. An example of this asymmetric procedure is given in Scheme 172.…”

Electrophilic Half-Sandwich (Carbene)metal (Metal = Fe, Ru, Os) Complexes: Recent Developments in Synthesis and Applications

“…These transient species can be generated from (α‐siloxyalkyl)iron derivatives [Fe(η 5 ‐ligand)(CO) 2 {CH(OSiMe)R}] (η 5 ‐ligand = C 5 H 5 , C 9 H 7 ). They are readily accessible from saturated or unsaturated aldehydes RCHO (R = Ph, CH 3 , p ‐C 6 H 4 OMe, p ‐C 6 H 4 Cl, p ‐C 6 H 4 Me, p ‐C 6 H 4 CF 3 , o ‐C 6 H 4 OMe, CH=CMe 2 ) by addition to the iron metallate [Na][Fe(η 5 ‐ligand)(CO) 2 ] and subsequent capture with ClSiMe 3 57…”