Reactivity of 1-substituted (pentadienyl)iron(1+) cations: Regioselectivity for addition of malonate nucleophiles; formation of (pentenediyl)- and (diene) iron complexes

Donaldson, William A.; Shang, Lewei; Tao, Changfa; Yun, Youngjun; Ramaswamy, M.

doi:10.1016/s0022-328x(97)00002-8

Cited by 25 publications

(17 citation statements)

References 33 publications

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“…The phthalimide group is situated trans to the (tricarbonyl)iron fragment, implying nucleophilic attack opposite to the metal center. The bond distances and angles for 18 (Table 2) are in good agreement with those for other (pentenediyl)iron complexes [4,9].…”

Section: Resultssupporting

confidence: 74%

“…For example, nucleophilic addition of triphenylphosphine to pentadienyl cation 1 proceeds at the unsubstituted terminus to generate 2E,4Z-dienoate complex 2a [3], while addition of stabilized carbon nucleophiles such as malonate anion proceeds at the internal C2 carbon to afford primarily (pentenediyl)iron complex 3b (Eq. 1) [4]. While the former regioselectivity is attributed to steric interactions in the transition state leading to attack at the unsubstituted carbon, the latter regioselectivity has been rationalized as the result of charge control; that is, the greater partial positive charge at the C2 and C4 pentadienyl carbons of 1 directs nucleophilic attack at these sites.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and reactivity of tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) cation

Chaudhury¹,

Donaldson²,

Bennett³

et al. 2004

Journal of Organometallic Chemistry

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Tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) hexafluorophosphate (7) was prepared in two steps from tricarbonyl(methyl 6-oxo-2,4-hexadienoate)iron. While addition of carbon and heteroatom nucleophiles to 7 generally occurs at the phenyl-substituted dienyl carbon to afford (2,4-dienoate)iron products, the addition of phthalimide proceeded at C2 to afford a (pentenediyl)iron product (18). Complex 18 was structurally characterized by X-ray diffraction analysis.

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Section: Resultssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Synthesis and reactivity of tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) cation

Chaudhury¹,

Donaldson²,

Bennett³

et al. 2004

Journal of Organometallic Chemistry

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“…For instance, the reaction of a variety of soft carbon nucleophiles with (1-methoxycarbonylpentadienyl)Fe(CO)3 + (2) proceeds via attack at an internal carbon of the dienyl ligand (eq 2). 3 This regioselectivity has been rationalized as the result of charge control; that is, the greater partial positive charge at the C2 and C4 pentadienyl carbons directs nucleophilic attack at these sites. In contrast, for (pentadienyl)iron cations bearing a C2 methyl substituent (e.g., 3a−c), attack by soft carbon nucleophiles generally occurs at the C5 pentadienyl terminus (eq 3).…”

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confidence: 99%

“…3,4,7 While the regiochemical directing effects of the two substituents are "matched" for addition of water, it should be noted that addition of water to 2 affords an E,Z-dienol complex, 8 while addition of water to 3a proceeds via the transoid form of the cation to give an E-dienol complex. 4a The electron-withdrawing ethoxycarbonyl substituent present on 4 increases the reactivity of this cation such that even weak nucleophiles (e.g., water) react via the cisoid form.…”

mentioning

confidence: 99%

“…Complex 12a was assigned a pentenediyl structure; in particular, the signal at δ −2.2 ppm in its 13 C NMR spectrum and the signals at δ 0.53 (dd) and −0.74 (dd) ppm in its 1 H NMR spectrum are characteristic of a methylene carbon which is σ-bound to iron. 3 In a has been granted for this version to appear in e-Publications@Marquette. American Chemical Society does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from American Chemical Society.…”

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Synthesis and Reactivity of (Tricarbonyl)(1-ethoxycarbonyl-2-methylpentadienyl)iron(1+) Cation

2001

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The Chemistry of Diene–Iron and Dienyl–Iron Complexes

Бауер

Knölker

2013

Patai's Chemistry of Functional Groups

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(η 4 ‐Diene)iron complexes and η 5 ‐dienyliumiron complex salts represent intriguing structures with planar π‐donating C 4 or C 5 ligands attached to the central iron atom. In many cases, they are rather stable compounds due to an 18‐electron count at the iron center. Tricarbonyl(η 4 ‐diene)iron complexes are formed from cyclic and acylic 1,3‐dienes and a tricarbonyliron source. Under certain conditions 1,4‐dienes can be employed with concomitant rearragement of the double bonds. The tricarbonyliron source can be a binary carbonyliron complex or a tricarbonyliron transfer reagent. (η 4 ‐1‐Azabutadiene)tricarbonyliron complexes have been proven to transfer the tricarbonyliron unit efficiently to the diene system. 1‐Azabutadiene ligands can even be employed in catalytic amounts. Chiral 1‐azabutadiene ligands enable the catalytic asymmetric synthesis of planar chiral (η 4 ‐diene)iron complexes. The tricarbonyliron fragment in (η 4 ‐diene)iron complexes is shielding one side of the diene system. Thus, it can be utilized to control stereoselective reactions in its proximity. Moreover, due to their stability (η 4 ‐diene)iron complexes can be employed as protected 1,3‐dienes. η 5 ‐Dienyliumiron complexes are generated from (η 4 ‐diene)iron complexes by two principal methods. Either by hydride abstraction at the α‐position of the diene ligand using triphenylcarbenium salts or by elimination of leaving groups adjacent to the diene system. η 5 ‐Dienyliumiron complexes are versatile electrophiles which react with a large variety of nucleophiles leading to functionalized (η 4 ‐diene)iron complexes. In most cases, nucleophilic attack at the terminus of the co‐ordinated dienylium system is preferred. Especially with C‐nucleophiles, the reaction is extremely useful for the construction of natural products or advanced synthetic precursors. Employment of substituted anilines as nucleophiles has paved the way to the total synthesis of a large number of biologically active carbazole alkaloids. After exploiting the activating, protecting or stereodirecting effect of the iron complex, the organic ligand is disengaged from the metal. A variety of mild demetalation procedures has been developed for this purpose. In addition to the stoichiometric reactions, first examples of catalytic applications of (diene)iron complexes are dicussed in this chapter.

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Reactivity of 1-substituted (pentadienyl)iron(1+) cations: Regioselectivity for addition of malonate nucleophiles; formation of (pentenediyl)- and (diene) iron complexes

Cited by 25 publications

References 33 publications

Synthesis and reactivity of tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) cation

Synthesis and reactivity of tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) cation

Synthesis and Reactivity of (Tricarbonyl)(1-ethoxycarbonyl-2-methylpentadienyl)iron(1+) Cation

The Chemistry of Diene–Iron and Dienyl–Iron Complexes

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