Ferrocene, formylation

Formyl- und Acyl-ferrocene werden mit Lithiumalanat/Aluminiumchlorid in glatter Reaktion zu Alkyl-ferrocenen reduziert6 (auch Triphenyl-zinnhydrid in Gegen-wart von Acetylchlorid ist geeignet7). 

The reaction with disubstituted formamides and phosphorus oxychloride, called the Vilsmeier or the Vilsmeier-Haack reaction,is the most common method for the formylation of aromatic rings. However, it is applicable only to active substrates, such as amines and phenols. An intramolecular version is also known.Aromatic hydrocarbons and heterocycles can also be formylated, but only if they are much more active than benzene (e.g., azulenes, ferrocenes). Though A-phenyl-A-methyl-formamide is a common reagent, other arylalkyl amides and dialkyl amides are also used. Phosgene (COCI2) has been used in place of POCI3. The reaction has also been carried out with other amides to give ketones (actually an example of 11-14),... 

One previous synthesis of ferrocene-containing condensation polymers via interfacial methods at room temperature has been reported by Knobloch and Rauscher, who formed low molecular weight polyamides and polyesters by reacting l,l -bis(chloro-formyl)ferrocene with various diamines and diols. Further, Carraher and co-workers have utilized interfacial techniques in the formation of other types of organometallic polymers. 

Ferrocene is similar to other highly reactive aromatic systems, in that it is readily formylated by N-methylformanilide in the presence of phosphorus oxychloride (5, 29, 107, 113, 118). Only the mono-substituted product, ferrocene-carboxaldehyde (XVI), is produced even when a large excess of formylating agent is used. 

AT32 liHuFeNO formyl ferrocene MeOH 50 PO HCI04 1 - RPE/MP 0-2 C=5... 

Ethynylferrocene A dry,1-L, three-necked, round-bottomed flask, equipped with a magnetic stirring bar, reflux condenser, and inlet/outlet valves for maintenance of an inert atmosphere as described above, is flushed with argon, charged with 26.0 g (95.0 mmol) of (2-formyl-1-chlorovinyl)ferrocene and 300 mL of anhydrous 1,4-diOxane (Note 12), and the apparatus is placed in an oil bath. The reaction mixture is heated to reflux and after 5 min at reflux, 250 mL of a boiling 1 N solution of sodium hydroxide (a 2.5-fold excess) is cautiously added as rapidly as possible in one portion (Note 13),... 

The procedure for the final elimination reaction is essentially that of Rosenblum, et al.2 A more detailed procedure is provided which improves reproducibility. Treatment of an ethereal solution of (2-formyl-1-chlorovinyl)ferrocene with sodium amide in liquid ammonia under anhydrous conditions is also an acceptable method,5 along with the method described which employs base-induced elimination using aqueous sodium hydroxide in dioxane.2 6 Compounds of the n-haloferrocene type are converted more or less quantitatively into alkynes by dehydrochlorination using... 

Ethynylferrocene Ferrocene, ethynyl- (8,9) (1271-47-2) (2-Formyl-1-chlorovinyl)ferrocene Iron, [(1-chloro-2-formylvinyl)cyclO-pentadienyl]cyctopentadienyl- (9) (12085-68-6)... 

Ferrocene reacts with acetyl chloride and aluminum chloride to afford the acylated product (287) (Scheme 84). The Friedel-Crafts acylation of (284) is about 3.3 x 10 times faster than that of benzene. Use of these conditions it is difficult to avoid the formation of a disubstituted product unless only a stoichiometric amount of AlCft is used. Thus, while the acyl substituent present in (287) is somewhat deactivating, the relative rate of acylation of (287) is still rapid (1.9 x 10 faster than benzene). Formation of the diacylated product may be avoided by use of acetic anhydride and BF3-Et20. Electrophilic substitution of (284) under Vilsmeyer formylation, Maimich aminomethylation, or acetoxymercuration conditions gives (288), (289), and (290/291), respectively, in good yields. Racemic amine (289) (also available in two steps from (287)) is readily resolved, providing the classic entry to enantiomerically pure ferrocene derivatives that possess central chirality and/or planar chirality. Friedel Crafts alkylation of (284) proceeds with the formation of a mixture of mono- and polyalkyl-substituted ferrocenes. The reaction of (284) with other... 

Mercurioferrocenes (290) and (291) are separable by Soxhlet extraction and these may be used to prepare bromoferrocene or dibromoferrocene or the iodo analogs. Alternatively, these halogenated ferrocenes are prepared from the ferrocene boronic acids or from anions (322) or (323). Bromoferrocene is the starting material for cyanoferrocene, azidoferrocene, or aminoferrocenes, generally in the presence of a copper salt. Amtnoferrocene can be acylated to produce an amide, or converted to isocyanoferrocene by a formylation/dehydration sequence (Scheme 96). The 1,T-diisocyanoferrocene is available from the bis(acyl)azide, itself derived from ferrocene dicarboxylic acid. ... 

SB-containing ferrocene groups have received much attention in the late 1990s. Thus, [1 + 1] and [2 + 2] macrocycles and a variety of acyclic SB-containing ferrocene groups have been prepared by reaction of formyl- and l,l -diformylferrocene with the appropriate diamine or by condensation of aminomethylferrocene with (56a), (57a), or 3-methoxy-2-hydroxybenzaldehyde.41 The compounds have been characterized by IR, NMR, Mossbauer spectroscopy, and FAB mass spectroscopy. 

More recently it has almost always been recommended to use the combination dimethylformamide-phosgene (e.g., for formylation of A, -dimethyl-aniline828) or dimethylformamide-phosphoryl chloride derivatives of 1,2-methylenedioxybenzene836 and of thiophen,837 as well as azulene838 and ferrocene,839 have been formylated in this way, some of them in excellent yield. Organic Syntheses contains directions for formylation of indole (97% yield of the 3-carbaldehyde)840 and W,W-dimethylaniline (80-84% yield of the para-aldehyde).841 The following is a further example in detail ... 

Formylation of ferrocene can be accomplished by reaction with triethyl orthoformate in bromobenzene at room temperature (92% yield). Somewhat lower yields are obtained in benzene or dichloromethane. 

Polychloromethanes can take part in photochemical electron-transfer reactions with aromatic compounds, leading (in alcohol as solvent) to products with oxygenated one-carbon substituents. It is reported that ruthenocene (95), like ferrocene, gives the corresponding ethoxycarbonyl, formyl, or ethoxymethyl compounds when irradiated with carbon tetrachloride, chloroform, or dichloro-methane, respectively. Carbazole (96) behaves in a similar way with CCI4, and the... 

The formylated ferrocene 108 reacts with 109 to give the aldol-condensation product 110 (Fig. 24) [18] the bridged Cp-rings possess phane structures itself, but the nomenclature refers to the bridged ferrocene nucleus [13, 33]. The ketone function can be reduced first, followed by hydrogenation of the C-C-double bond or vice versa to give 111 (Fig. 24) [18]. 

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