Ferrocenyl iodide

Deprotonation of l-methyl-3-ferrocenylimidazolium tetrafluoroborate or iodide (98JOM(552)45) by lithium di-Mo-propylamide and subsequent reaction with W(C0)5-THF gives the carbene complex 107 and bis-carbene 108, even when excess W(CO)j THF is applied (99JOM(572)177). Numerous ferrocenyl benzimidazoles are known (97RCR613, 99JOM(580)26). 

Macrocycles attached to redox responsive groups such as ferrocene (78) can give selective transition metal ion receptors. The X-ray structure reveals a five-coordinate zinc with distorted square-pyramidal geometry bound to the four macrocycle nitrogens and an iodide. In the solid state the two ferrocenyl groups are positioned on the same side of the ligand with distances to the metal center of 5.347(7) and 6.120(8) A and these distances can be related to the redox behavior.689... 

Among the various catalyst types investigated in recent years for the hydrogenation of imines, Ir-diphosphine complexes have proved to be most versatile catalysts. The first catalyst of this type generated in situ from [Ir(cod)Cl]2, a chiral diphosphine and iodide was developed by the Ciba-Geigy catalysis group in 1985. Ir ferrocenyl diphosphines (josiphos) complexes in presence of iodide and acid... 

The search for a commercially viable process took many years [126], Several approaches with Rh or Ir complexes using commercially available diphosphine ligands were not successful. A critical breakthrough was achieved when Ir complexes with a new class of ferrocenyl-based ligands (now called Solvias Josiphos) were used. Extremely active and productive catalysts were obtained, especially in the presence of acid and iodide ions. Different Josiphos ligands were tested and a selection of the best results obtained is shown in Table 37.5. 

An extension of this methodology, by hexafunctionalization of the arene group in 13 using ferrocenylbutyl iodide 14 under basic conditions, gave the hexafluoro-phosphate salt of the heptanuclear Fe(Il) complex cation 15 in 65% yield. Photolysis of 15, under similar conditions which converted 8 into 9, led to isolation of the neutral ferrocenyl complex 16 by selective decomplexation of the central... 

The reaction of ferrocenylazide and dimethyl e o-cis-3,6-endoxo-A 4-tetrahydrophthalate gives the ferrocenyl compound 68.70 Reaction of cyanoferrocene with trimethylsilyl azide and aluminum chloride gave ferrocenyltetrazole (69) as the sole organometallic product.71 Alkylation of 69 with methyl iodide affords two A-methyl derivatives. The major product is assigned the structure 2-methyl-5-ferrocenyl-tetrazole, while the minor product is assumed to be the 1-methyl isomer. 

Reaction of (2-methyl-5-)- and (2-methyl-6-benzothiazoIyl)-dimethyltriazene or 2-methyl-5- and 2-methyl-6-benzothiazolyl-diazonium salts with ferrocene gave 136 (R = ferrocenyl, R = H R = H, R = ferrocenyl, respectively).121 Use of the diazonium salts also led to the isolation of some 1,1 disubstituted ferrocenes in this reaction. The compounds 136 were used to prepare thiacyanines. Reaction of ferrocenecarboxaldehyde with the ethiodide of 2-methyI-benzothiazole followed by treatment with potassium iodide gave 137.121... 

One key goal of catalyst development is to move from the more expensive alkyl and aryl iodides and bromides to the cheaper chlorides and the environmentally more desirable tosylates. The latter tend to react less well bnt the nse of basic, bulky ligands like P(tBn)3 and a nnmber of ferrocenyl-substituted phosphines has improved the situation. 

Chiral ferrocenyl derivatives with a trimethylammonium group in the a-position are known to undergo nucleophilic substitution with complete retention of configuration [2]. Quaternization of 3 with methyl iodide followed by reaction with iV-methylethanolamine, (S)-prolinol, or (lS,2R)-ephedrine gave the corresponding (R,S)-2-iodoferrocenes 4a, 4b, and 4c in 80 — 90% yield with complete retention of configuration (Scheme 3-4). Diastereomers 4d and 4e were similarly prepared starting with (S,R)-3. 

The treatment of 3-phenyl- and 3-ferrocenyl-3-chloropropenal with sodium sulfide nonahydrate gave rise to intermediate 3-phenyl- and 3-ferrocenyl-3-thiopropenal, which produced with aniline the 1-phenyl- (29a) and l-ferrocenyl-3-phenylaminothioprope-non 29h. The reaction of 29a,h with iodine in methanol yielded the oxidized bis(2,5-diphenylisothiazolium) octaiodide 30a (85%) and 2-phenyl-5-ferrocenylisothiazolium pentaiodide 30h (91%) (99ZAAC511). The structures of these iodides 30a (X = 17 ) and 30h were confirmed by X-ray diffraction (99ZAAC511, Scheme 8). 30a (I8 ) also formed a layer structure with isothiazolium cations and polyiodide anions. 

The 6,5-bicyclic synthesis outlined above has been extended to indolizidines, formed by AHR of a suitable prochiral alkenyl iodide such as 28, which can be easily prepared by allylation of the lactam 27. In contrast to purely carbogenic systems, however, the most effective ligand proves to be BPPFOH ((R)-a-[(S)-l ,2-bis(diphenylphosphino)ferrocenyl] ethyl alcohol) 31 [35] which gives results clearly superior to those obtained with BINAP (Scheme 8) [36,37]. 

Further, ferrocenyl(alkyl)imidazole compound (30) was made by a similar method. Reaction of compound 29 with 1 in CH3CN affords imidazole (30) in excellent yield. After methylation with methyl iodide followed by deprotonation, 30 was transformed into a planar-chiral stable carbene (31) (eq 25). 

Palladium(ii) complexes of imidazoline-2-ylidenes with pendant 1- and 1,3-di-methylferrocenyl substituents, 78 and 79, were prepared by the reaction of the relevant benzimidazolium salt with Pd(OAc)2 and a crystal structure of 79 obtained. " In common with other related carbene complexes, the plane of the benzimidazole rings are twisted with respect to the palladium coordination plane the dihedral angle is 85.17(23)°. The closely related l-ferrocenyl-3-methyl-benzimidazolin-2-ylidene complex (in which there is no methyl linker between the N and the ferrocenyl group) has also been prepared by a similar route. " l-Ferrocenylmethyl-3-benzylimidazolidinium and 1-ferrocenyl-methyl-3-(2,4,6-trimethylbenzyl)imidazolidinium iodide salts were prepared and complexed to Pd by an in situ deprotonation route. " Cyclic voltammetry studies on the salts and the Pd complex show a number of redox processes, indicating that the ferrocenyl substituents are electronically isolated from the remaining molecular framework. 

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