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The Friedel–Crafts acetylation (Ac2O/AlCl3) reaction of azinylferrocenes occurs regioselectively at position 1′. Acetylated derivatives upon reaction with Ph3P=CH2 give the corresponding 1-azinyl-1′-isopropenylferrocenes.

In the present review comparative data concerning various synthetic approaches and methodologies used in the series of ferrocene and cymantrene derivatives to create various materials, namely, catalytic systems, sensory and other molecular devices, polymers as well as physiologically active substances, for the period from 2000 till 2016 are given. Aspects of practical application of the above compounds are also considered.

A highly selective coupling of azines with aromatic nucleophiles (SN H-reactions) in the presence of a heterogeneous oxidation system O2/CdS/TiO2 upon exposure to daylight was accomplished.

Novel non-symmetric tridentate N,N,O-ligand was obtained by direct substitution of hydrogen in 3-(2-pyridyl)-6-phenyl-1,2,4-triazine. Three binuclear cobalt(II), copper(II) and zinc(II) carboxylate complexes of 3-(2-pyridyl)-5-(2-hydroxynaphthalen-1-yl)-6-phenyl-1,2,4-triazine anion (HL1), [M2(Piv)2(L1)2] (M = Co, Cu, Zn; Piv = Me3CCO2-), were synthesized and characterized by elemental analysis and IR spectroscopy. The complexes structures were determined by single crystal X-ray diffraction analysis. The magnetic property studies indicate that cobalt(II) complex exhibits weak ferromagnetic coupling (J = 1.2(1) cm−1) between two high-spin Co(II) ions linked by double μ-O phenoxo bridges. According to magnetic property studies as well as X- and Q-band EPR spectra for copper(II) complex, the specific structure of the Cu2O2 fragment leads to the predominance of dipole–dipole interactions and weak antiferromagnetic coupling (J = -3.64(3) cm−1).

The facile C–C coupling reaction of activated forms of azaaromatics (azine-N-oxides) with cymantrenyl lithium, as a nucleophile, has first been carried out. It has been established that aromatization of intermediate adducts can be realized through either oxidative or eliminative pathways, depending on the structure of the starting azine N-oxide. In particular, the dihydroazinyl intermediates, bearing the additional N(4)-atom relative to the N-oxide group, proved to undergo aromatization through the eliminative pathway. The X-ray studies of 3,6-diphenyl-1,2,4-triazine-5-yl-cymantrene have revealed that it is crystallized in both orthorhombic and monoclinic forms. © 2018 Elsevier B.V.

Novel complexes of 1,2-P,N-bidentate ferrocenyl ligands with AgOAc or with [RuCl2(PPh3)3] as catalysts have been studied in asymmetric synthesis. The catalytic activity of these systems have been studied in [3+2]-cycloaddition of azomethine ylides with olefins and the asymmetric transfer hydrogenation of ketones.

New acyclovir analogues were obtained by reaction of 1,2,4-triazolo[1,5- a ]pyrimidin-7-ones 4a – i with (2-acetoxyethoxy)methyl acetate 5 in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) as catalyst (Vorbruggen procedure). Coupling between compounds 4a – f and 5 led to a mixture of N3- and N4-isomers 6 and 7 , respectively. On the contrary, the reaction of compounds 4g – i with 5 proceeded selectively with formation of N3-isomers only. It was found that the ratio of 6a – f and 7a – f depends on the presence or the absence of N , O -bis(trimethylsilyl)acetamide (BSA). Glycosylated products 6a – f and 7a – f underwent reversible isomerization under TMSOTf treatment. The ratio of glycosylated products of the coupling reaction between 4 and 5 was thermodynamically controlled. A similar reaction occurred if ZnCl 2 was chosen as a catalyst, although lower yields of the acyclic analogues of nucleosides were observed. The glycosylation of other purines (adenine and guanine) can be achieved via the non-BSA modification of the Vorbruggen procedure.

A direct C-C-coupling of ferrocenyl- and cymantrenyllithium with 5-(het)aryl-1,2,5- oxadiazolo[3,4-b]pyrazines was accomplished. Main characteristics of the SNH-reaction products were obtained, as well as crystallographic data on the spatial structure of oxadiazolopyrazinylferrocenes and -cymantrenes synthesized.

A versatile synthetic protocol was proposed for direct C–C coupling of a cymantrene fragment with various azaheterocycles on the basis of nucleophilic substitution of hydrogen in the absence of metal catalysts.

Two synthetic routes to the chiral azinylferrocenes (CAFs) 5 and 15, key intermediates for the synthesis of new enantiomerically enriched P,N-ligands, have been compared. The first approach is based on the palladium-catalyzed cross-coupling reaction of halogenated azines with organozinc derivatives of ferrocenes (the Negishi reaction). The second approach exploits a new synthetic methodology, which provides a shorter pathway, through the direct C–H functionalization of aromatics by the C–C coupling of halogen-free (hetero)arenes with lithium ferrocenes bearing stereogenic C and S atoms. The palladium complexes of P,N-ligands have been used as catalysts for the Tsuji–Trost reaction, which proceeds with high enantioselectivity to give allylic substitution products in good yields.