Tricarbonyliron Complexes Research Articles

Stereochemical factors associated with the rearrangement of (2-ethyl-1-azabuta-1,3-diene)tricarbonyliron(0) complexes

Reaction of (2-ethyl-1,4-diphenyl-1-azabuta-1,3-diene)tricarbonyliron(0) 4 and (2-ethyl-1-benzyl-4-phenyl-1-azabuta-1,3-diene)tricarbonyliron(0) 7 with lithium diethylamide leads to selective formation of the corresponding endo (1-methyl-2-amino buta-1,3-diene)tricarbonyliron(0) complexes 5 and 8, respectively. In each case there is no evidence for the exo complexes 6 and 9.

Transition metal complexes in organic synthesis, part 50. Asymmetric catalytic complexation of 1-methoxycyclohexa-1,3-diene by the tricarbonyliron fragment using amino acid-derived 1-azabuta-1,3-dienes

l-Amino acid esters as chiral auxiliaries in the asymmetric complexation of 1-methoxycyclohexa-1,3-diene with pentacarbonyliron afford the R-enantiomer of the corresponding planar chiral tricarbonyliron complex in up to 24% ee.

Highly stereoselective synthesis of 3-amino-3,6-dideoxy-aldohexoses by tin triflate mediated aldol condensation reaction of tricarbonyl iron α-aminodienone complexes. Total synthesis of multiprotected mycosamine

The divalent tin enol ether of the racemic N-BOC α-aminodienone tricarbonyliron complex 4 reacts with both enantiomers of protected lactaldehydes to predominantly yield one optically active ketol diastereoisomer (45 %). From the enantiomerically pure complex (S)-(+)-4 and (R)-(+) tert butyldimethylsilyloxylactaldehyde this ketol is obtained almost alone (isolated 86 %). From there, the multi-protected 3-amino-3,6-dideoxy- d-aldohexose mycosamine is obtained in a few high yielding steps (decomplexation, stereospecific reduction to a 1,3-diol, transformation into a diacetate and ozonolysis; absolute configurations S,S,S,R). By reduction of the ketol before decomplexation, the stereochemistry of the reaction is completely reversed (control by the Fe(CO) 3 and not by the hydroxyl group), giving also access to the R,S,S,R series. (Structures determined by X-ray diffraction).

A Novel Method for the Demetalation of Tricarbonyliron–Diene Complexes by a Photolytically Induced Ligand Exchange Reaction with Acetonitrile

The photochemical exchange of all three carbonyl ligands with acetonitrile converts tricarbonyliron–diene complexes into the very labile triacetonitrile-iron–diene complexes. These easily demetalate in high yields to the corresponding free ligands on injection of air at −30°C [Eq. (1)]. The novel demetalation procedure is applied to the tricarbonyliron complexes of cyclopentadienones, cyclohexa-1,3-dienes, and buta-1,3-dienes.

A Novel Method for the Demetalation of Tricarbonyliron-Diene Complexes by a Photolytically Induced Ligand Exchange Reaction with Acetonitrile.

The photochemical exchange of all three carbonyl ligands with acetonitrile converts tricarbonyliron-diene complexes into the very labile triacetonitrile-iron-diene complexes. These easily demetalate in high yields to the corresponding free ligands on injection of air at -30°C [Eq. (1)]. The novel demetalation procedure is applied to the tricarbonyliron complexes of cyclopentadienones, cyclohexa-1,3-dienes, and buta-1,3-dienes.

Transition metal complexes in organic synthesis. Part 47.1 Organic synthesis via tricarbonyl(η4-diene)iron complexes

The protection of conjugated dienes by coordination to the tricarbonyliron fragment offers many potential applications of the resulting complexes to organic synthesis. The preparation of tricarbonyl(η4-1,3-diene)iron complexes is readily achieved by a 1-azabutadiene-catalyzed complexation of the free ligands. An asymmetric catalytic complexation of prochiral cyclohexa-1,3-dienes with pentacarbonyl-iron using chiral 1-azabutadienes affords chiral nonracemic complexes. The chiral tricarbonyliron complexes of acyclic butadienes represent versatile starting materials for the synthesis of a broad range of polyunsaturated natural products. Consecutive carbon–carbon and carbon–nitrogen bond formations of the tricarbonyliron–cyclohexa-1,3-diene complexes and arylamines provide many biologically active carbazole alkaloids and a tetracyclic subunit of the discorhabdin alkaloids. The iron-mediated [2+2+1] cycloaddition of trimethylsilylacetylenes and carbon monoxide affords stable 2,5-bis(trimethylsilyl)-substituted cyclopentadienones which are useful substrates for further cycloadditions.

Stereoselective synthesis of retinoid isomers using tricarbonyliron complex and its application

Abstract

Retinoids and Related Compounds. Part 22. Synthesis of .BETA.-Ionone Analog Tricarbonyliron Complexes.

The synthesis of β-ionone analog tricarbonyliron complexes was investigated. N-Methoxy-N-methyl-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-propenamide (Weinreb amide), prepared from the corresponding ethyl ester and N,O-dimethylhydroxylamine hydrochloride, reacted smoothly with various organometallic reagents to afford the β-ionone analogs in good to excellent yields. Treatment of these compounds with dodecacarbonyltriiron afforded the corresponding tricarbonyliron complexes in high yields.

Photolytic induction of the asymmetric catalytic complexation of prochiral cyclohexa-1,3-dienes by the tricarbonyliron fragment1

Photolytic induction of the asymmetric catalytic complexation of prochiral cyclohexa-1,3-dienes by the tricarbonyliron fragment using a camphor-derived azadiene catalyst provides the corresponding tricarbonyliron complexes quantitatively in up to 86% ee.

ChemInform Abstract: Utility of a Diene—Tricarbonyliron Complex as Mobile Chiral Auxiliary: Iterative Use for Constructing Contiguous Chiral Centers.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Regioselective Acylation of (5‐Alkylidene‐1,3‐cyclohexadiene)tricarbonyliron Complexes by the Reaction with Organometallic Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Preparation of m‐Acylaniline Derivatives by the Reaction of Tricarbonyl(cyclohexadienone O‐benzyloxime)iron Complex and Higher Order Cuprates

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A New Iron-Mediated Strategy for the Synthesis of α-Lipoic Acid and Analogues

Dithioester 10 was synthesized in 6 steps from tricarbonyl(diene)iron complex 3. Compound 10 is not only a key intermediate for the synthesis of methyl lipoate (13) but could also be of interest for the preparation of various labelled compounds and structural analogues.

1,4-Diaryl-1-azabuta-1,3-diene-Catalyzed Complexation of Cyclohexa-1,3-diene by the Tricarbonyliron Fragment: Development of Highly Efficient Catalysts, Optimization of Reaction Conditions, and Proposed Mechanism

The 1,4-diaryl-1-azabuta-1,3-diene-catalyzed complexation of cyclohexa-1,3-diene with either nonacarbonyldiiron or pentacarbonyliron is reported to provide high yields of the tricarbonyl(η4-cyclohexa-1,3-diene)iron complex. This procedure enables exploitation of both tricarbonyliron fragments of nonacarbonyldiiron for the complexation of dienes for the first time. Using 12.5 mol % of 1-(4-methoxyphenyl)-4-phenyl-1-azabuta-1,3-diene and optimized reaction conditions (nonacarbonyldiiron, dimethoxyethane, reflux, 16.5 h, or pentacarbonyliron, dioxane, reflux, 45 h), a quantitative catalytic complexation of cyclohexa-1,3-diene is feasible with both reagents. An extensive study with a broad range of 1,4-diaryl-1-azabuta-1,3-dienes shows that the efficiency of the catalysts strongly depends on the substituents of the two aryl rings. Remarkably high activities are found for those catalysts deriving from condensation of cinnamaldehyde and ortho-methoxy-substituted arylamines. A hexacarbonyldiiron complex of 1-(4-methoxyphenyl)-4-phenyl-1-azabuta-1,3-diene is obtained as a byproduct of the catalytic complexation and is structurally confirmed by X-ray crystallography. A mechanism supported by the experimental findings is proposed.

Diene tricarbonyl iron complexes bearing a free diazo group. III. 1 Synthesis of pyrazoles and chiral complexes with α-aminoacid or dienylcyclopropane substructures by 1,3-dipolar cycloaddition reactions

Cycloaddition reactions of acetylenic and olefinic dipolarophiles with diazoketones and a diazoester linked to tricarbonyl iron coordinaced diene units were investigated. 1H-pyrazoles were obtained directly from acetylene carboxylic esters by [1,5] group migrations at the stage of the primary formed 3H-pyrazoles. With methyl acrylate, the cycloaddition led to complexes of Δ 2-pyrazolines and at slightly more elevated temperature, with the diazoester, to cyclopropane esters. All diastereomers formed in each reaction could easily be separated by simple chromatography on silica gel, illustrating one of the practical advantages of the use of tricarbonyl iron complexes. In the optically active series, this allowed the high ee synthesis of various products with α-aminoacid or dienylcyclopropane substructures.

Synthesis, Molecular Structure, Fluxional Behavior, and Tricarbonyliron Transfer Reactions of (η4-1-Azabuta-1,3-diene)tricarbonyliron Complexes

The (η4-1-azabuta-1,3-diene)tricarbonyliron complexes 10 are easily prepared in high yield by condensation of the corresponding arylamines 7 with the cinnamaldehydes 8 and subsequent ultrasound-promoted complexation of the resulting 1-azabuta-1,3-dienes 9 with nonacarbonyldiiron. The complexes 10 are shown to represent excellent reagents for the transfer of the tricarbonyliron fragment onto cyclohexa-1,3-diene (1a). The structural characterization for the complexes 10 is achieved by IR, 1H-NMR, and 13C-NMR spectroscopy, as well as X-ray crystallography of 10b, 10c, and 10l. Using variable temperature 13C-NMR spectroscopy the fluxionality of the complexes 10a, 10b, 10c, 10e, and 2 is investigated and the activation barrier for the turnstile rotation of the tricarbonyliron fragment is determined. The transfer reaction and the structural factors influencing the transfer of the tricarbonyliron fragment are extensively investigated.

Regioselective Acylation of (5-Alkylidene-1,3-cyclohexadiene)tricarbonyliron Complexes by the Reaction with Organometallic Reagents

Abstract Reaction of [(1,2,3,4-η)-5-alkylidene-1,3-cyclohexadiene]tricarbonylirons and organometallic reagents generates acyl[(1,2,3,4,5-η)-1-alkylcyclohexadienyl]dicarbonylirons. The acyl group in these complexes migrates to the cyclohexadienyl moiety under carbon monoxide atmosphere, providing [(1,2,3,4-η)-6-acyl-2-alkyl-1,3-cyclohexadiene]tricarbonylirons, which are further transformed to m-alkylphenyl ketones by the oxidation with trimethylamine N-oxide.

Preparation of m-Acylaniline Derivatives by the Reaction of Tricarbonyl(cyclohexadienone O-benzyloxime)iron Complex and Higher Order Cuprates

Abstract Reaction of tricarbonyl[(2,3,4,5-η)-2,4-cyclohexadien-1-one O-benzyloxime]iron and organocuprates, followed by the treatment with acetic anhydride and carbon monoxide, affords [(1,2,3,4-η)-1-(N-acetoxy-N-benzyloxyamino)-5-endo-acyl-1,3-cyclohexadiene]tricarbonylirons, which are converted to m-acylaniline derivatives by treating with potassium carbonate.

Diastereoselective Allylations of Enantiopure 3- and 4-Substituted η4-(1Z)-(Sulfinyldienal)iron(0) Tricarbonyl Complexes

Diastereoselectivity of allylations of enantiopure 3- and 4-substituted η4-(1Z)-(sulfinyldienal)iron(0) tricarbonyl complexes is dependent on the nature of the alkyl substituent. For 1-sulfinyl-1,3-pentadien-5-al iron complexes (11a−d), the aldehyde predominately reacts through the s-cis conformer, with diastereoselectivites as high as 95:5 (for homoallylic alcohol 13d). For 3-formyl-1-sulfinyl-1,3-butadiene iron complexes (12a,b), the aldehyde predominately reacts through the s-trans conformer (diastereomer ratio for homoallylic alcohol, 14b, 89:11).

Nucleophilic additions of phenylsulfonyl-substituted tricarbonyl(1,3-cyclohexadiene)iron complexes

Tricarbonyl[ η 4-2-(phenylsulfonyl)-1,3-cyclohexadiene]iron(0) ( 3) was prepared in good yield from 2-(phenylsulfonyl)-1,3-cyclohexadiene and Fe 2(CO) 9 using azadiene 2 as the catalyst. The reaction of 3 with nucleophiles proceeded only at the C-4 position under thermodynamic (25°C) or kinetic (−78°C) condition. Careful treatment of 3 with Ph 3CPF 6 at low temperature regiospecifically gave the tricarbonyl[(1-5- η 5)-3-(phenylsulfonyl)cyclohexadienyl]iron(I) complex 6. The η 5-complex 6 was more reactive than the η 4-complex 3, and reacted with various nucleophiles stereo- and regiospecifically at the C-1 position. The addition products 9 could be demetallated to give functionalized dienyl sulfones 10.