Iron tosylate

An alternative chemical synthesis mefliod to eonventional solution-based CP deposition is the so-called vapour phase polymerization (VPP) teehnique (Mohammadi et al. 1986 Kim et al. 2003 Wintiier-Jensen and West 2004 Winther-Jensen et al. 2005 Fabretto et al. 2008). There is much interest in this method because it provides high eontrol over CP film thickness, uniformity, and density. Typically, the formation of conjugated polymers is carried out directly on the surface of the substrate in a two-step process. First, fire oxidant such as iron tosylate in n-butanol is applied on the substrate using solvent coating processes and then the coated surface is exposed to a reactive CP monomer vapour. PEDOT films have been reported to have with conductivities as high as approximately 3400 S.cm or S cm for a thickness of 60 mn, which is equivalent to commercially available indium tin oxide (ITO) (Fabretto et al. 2012). 

With regard to the pressure effects, we have, as usual, been interested in systems that are not simple. One system we have been looking at involves water-soluble porphyrins. Actually, the only reactions we have studied thus far involve the iron(III) and manganese(III) tetra(4-N-methylpyridyl)porphyrin complexes. These complexes are in the form of tosylate salts, which causes some problems. The rate constants are on the order... 

Amination of alkanes (cyclohexane, heptane, adamantane) was achieved with iron and manganese porphyrin catalysts by tosylimidoiodobenzene to yield tosyl-amino derivatives.200 Selective 1-substitution of adamantane (56% yield) and 2-substitution of heptane (66% selectivity) were reported. 

The X-ray crystal structure of the 1 -tosyl-1H-1,2-diazepine (10) shows a boat conformation with N(l) at the prow (Figure 1) (72T581). Double bonds are clearly localized at N(2)—C(3) 1.255 A, C(4)—C(5) 1.326 A, and C(6)—C(7) 1.333 A, and the imine bond is isolated, whereas bond delocalization is present in the butadiene-like part C(4)—C(5)—C(6)—C(7). In contrast, when the diazepine is complexed with Fe(CO)3, for example (11), the iron atom is bound to the butadiene moiety C(4) to C(7), as also occurs in the lf/-azepine and l-methoxycarbonyl-l//-azepine complexes the N(l) atom adopts a planar sp2 configuration and the seven-membered ring consists of the two planar parts bent along the C(4)... C(7) line by 140° (70AG(E)958). 

Xlld does not involve the chiral center, so if the reaction takes place by this pathway, the migration of the alkyl group from sulfur to palladium (with the concomitant or subsequent loss of sulfur dioxide) must take place with inversion of configuration at carbon. Inversion of configuration at carbon has been observed in the reverse-type reaction, the sulfur dioxide insertion into a carbon-iron sigma bond (49). Nucleophilic displacement at carbon in compounds of type Xld is unusually difficult, so the reaction via the sulfite intermediate Xlld would appear to be more likely. Conversion of the tosylate of l-phenyl-2,2,2-trifluoroethanol to the corresponding chloride, a reaction which takes place in the presence of tetra- (n-butyl) ajnmonium chloride with inversion of configuration at carbon, requires 100°C for 24 hrs in dimethylsulfoxide. 

The first reports on iron-catalyzed aziridinations date back to 1984, when Mansuy et al. reported that iron and manganese porphyrin catalysts were able to transfer a nitrene moiety on to alkenes [90]. They used iminoiodinanes PhIN=R (R = tosyl) as the nitrene source. However, yields remained low (up to 55% for styrene aziridination). It was suggested that the active intermediate formed during the reaction was an Fev=NTs complex and that this complex would transfer the NTs moiety to the alkene [91-93]. However, the catalytic performance was hampered by the rapid iron-catalyzed decomposition of PhI=NTs into iodobenzene and sulfonamide. Other reports on aziridination reactions with iron porphyrins or corroles and nitrene sources such as bromamine-T or chloramine-T have been published [94], An asymmetric variant was presented by Marchon and coworkers [95]. Biomimetic systems such as those mentioned above will be dealt with elsewhere. 

Iron(m) salts are effective catalysts for sp -sp2 coupling, which catalyze the reaction of alkylmagnesium compounds with aryl chlorides, triflates and tosylates as well as hetaryl chlorides in THF-NMP at 0°C (Scheme 49, 50).139 139a-i39d... 

Alkenes. This reagent reacts with an alkyl bromide (or tosylate) to form an iron complex of type 2. Treatment with trityl tetrafluoroborate in CH2CI2 at 0 abstracts a hydride ion from a /3-carbon atom of 2 to form an alkene iron complex (3). The alkene 4 is liberated quantitatively and without isomerization by treatment with sodium iodide in acetone." Because of the size, (C6H5)3C" abstracts a hydride ion preferentially from a methyl rather than a methylene group. In addition, electronic factors may be involved. This elimination reaction is therefore useful for preparation of 1-alkenes. 

In method (a), an alkyl halide (or tosylate) reacts with [Fe(CO)4] " in N-melhyl-2-pyrrolidone to give an anionic iron alkyl (1), some of which have been isolated and characterized. Further reaction with another alkyl halide gives a complex tentatively formulated as (2), which may decompose to the ketone via the complex (3) formed by solvent-assisted migratory insertion. No alkyl coupling products are detected. 

Now for the organometallk bit. As described in the chapter (p. 1318) the ferrate anion is ver nucleophilic and displaces the tosylate from the primary carbon. Carbonyl insertion gives an ire acyl complex and the neutral iron atom forms a it-complex with the alkene. The carbonyl transferred to the far end of the alkene as six-membered rings are preferred to five-membered ore and protonation of the C-Fe bond completes the reaction. 

Furstner, A., Leitner, A. Iron-catalyzed cross-coupling reactions of alkyl-Grignard reagents with aryl chlorides, tosylates, and triflates. Angewandte Chemie, International Edition 2002,41, 609-612. 

The present methods for the preparation of N acyl a arylenamides include (i) reductive acylation of ketoximes with iron metal [2] or phosphines [3] in the presence of acyl chlorides or acyl anhydrides (Method A) (ii) metal catalyzed coupling of vinyl halides [4], triflates [5], or tosylates [6] with amides (Method B) (iii) reaction of imine intermediates derived from nitriles with acyl chlorides or anhydrides (Method C) [7] and(iv) Pd catalyzed coupling ofaryl tosylates with N acyl vinylamines (MethodD) [8]. 

An interesting property of thin films of the iron(II) complexes in the mesophase is their thermochromism. A reversible colour change from purple (low-spin state) to whitish (high-spin state) was observed by heating or cooling the compound around 60 °C. This work was extended to complexes in which the tosylate counter ions were replaced by tetrafluoro-borate and triflate ions. The resulting compounds were polymeric with a one-dimensional structure. Several of the complexes were liquid-crystalline at room temperature and their mesophase was either hexagonal... 

---