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Article

Intramolecular Transformations of 3-Cyanoamino- and 3-Cyanoimino-1,2-diferrocenylcyclopropenes

by
Elena Ivanovna Klimova
1,*,
Tatiana Klimova
1,
Marcos Flores-Alamo
1,
Leon Vladimirovich Backinowsky
2 and
Marcos Martinez Garcia
3
1
Universidad Nacional Autónoma de México, Facultad de Química, Cd. Universitaria, Coyoacán,C.P. 04510, México D.F., Mexico
2
N.D. Zelinsky Institute of Organic Chemistry , Russian Academy of Sciences, 47 Leninsky prosp., 117913 Moscow, Russia
3
Instituto de Química, Universidad Nacional Autónoma de México, Cd. Universitaria, Coyoacán, C.P.04510, México D.F., Mexico
*
Author to whom correspondence should be addressed.
Molecules 2009, 14(9), 3161-3175; https://doi.org/10.3390/molecules14093161
Submission received: 13 June 2009 / Revised: 20 July 2009 / Accepted: 12 August 2009 / Published: 26 August 2009
(This article belongs to the Special Issue Ferrocenes)
Browse Figures
Versions Notes

Abstract

:
3-Cyanoamino-1,2- and -2,3-diferrocenylcyclopropenes 6a,b and 11a,b prepared by the reaction of diferrocenylcyclopropenylium salts with sodium cyanamide undergo smooth intramolecular transformations with both conservation of the three-membered ring [affording 3-cyanoimino-1,2-diferrocenylcyclopropene (8)] and its opening [affording Z-3-morpholino- and Z-3-piperidino-3-(cyanoimino)-1,2-diferrocenylprop-1-enes 7a,b and Z-3-cyanoimino-2,3-diferrocenyl-1-methylthioprop-1-ene(10)]. 3-Cyano-imino-1,2-diferrocenylcyclopropene (8) reacts with hydrazine to form 3-amino-6-ferrocenyl-5-ferrocenylmethyl-1,2,4-triazine (12) and Z-2,3-diferrocenylacrylohydrazide N-cyanoimide (13) as a result of intramolecular transformations. The structures of the compounds obtained were determined by IR, 1H- and 13C-NMR spectroscopy and mass spectrometry. The structures of compounds 7a and 10 were additionally confirmed by their X-ray diffraction analysis data.

Graphical Abstract

Introduction

The range of natural compounds comprising cyclopropane or cyclopropene fragments is fairly broad. Many of them are of particular interest due to their peculiar inherent biological activities [1,2,3,4,5]. In synthetic practice, compounds with a three-membered ring represent both the target products and intermediates in various carbon skeleton transformations [6,7,8]. These processes include, as a rule, ring opening reactions [8] into intermediate allylic cations or vinylcarbenes that serve as “building blocks” in organic synthesis. The presence of ferrocenyl substituents in the three-membered ring greatly facilitates these ring opening reactions [9,10,11,12,13]. This allows the use of ferrocenylcyclopropanes/cyclo-propenes prepared by directed synthesis for their subsequent transformation into long-chain conjugated systems [6,8] and carbo- and heterocycles [14,15,16,17] incorporating iron-containing fragments. The effect of the nature of other functional groups and hetero-substituents on the ease of the three-membered ring opening of ferrocenylcyclopropenes has been but scantily explored. In particular, it has been established that the small ring opening occurs very readily for 2,3-diferrocenyl-1-methylthiocyclo-propenes 1a-d [15,16,17,18,19]. These are formed in the reaction of diferrocenyl(methylthio)cyclopropenylium iodide (2) with active methylene reagents (diethyl malonate, malononitrile, nitroalkanes) and are further converted via 2,3-diferrocenyl-1-methylthiovinylcarbenes 3a-d into diene systems 4a-d with ferrocenyl substituents and terminal functionalities as a result of intramolecular migration of a functional group (Scheme 1).
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Scheme 1. Reaction of diferrocenyl(methylthio)cyclopropenylium iodide (2) with active methylene reagents.
Scheme 1. Reaction of diferrocenyl(methylthio)cyclopropenylium iodide (2) with active methylene reagents.
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Studies on this type of chemical transformations are of undoubted interest for specialists in theoretical, physical and synthetic organic chemistry, as well as to the search for compounds with such valuable properties. In the present work, we report the results of studies on the reactions of sodium cyanamide with diferrocenyl(morpholino)- and -(piperidino)cyclopropenylium tetrafluoroborates 5a,b and diferrocenyl(methylthio)cyclopropenylium iodide (2).

Results and Discussion

The starting diferrocenylcyclopropenylium salts 5a, 5b, and 2 (Figure 1) were prepared from 2,3-diferrocenyl-cyclopropenone as described earlier [16,20,21].
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Figure 1. Starting diferrocenylcyclopropenylium salts 5a, 5b, and 2.
Figure 1. Starting diferrocenylcyclopropenylium salts 5a, 5b, and 2.
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We found that diferrocenyl(morpholino)- and -(piperidino)cyclopropenylium tetrafluoroborates 5a,b) react regioselectively with sodium cyanamide at 20 ºC (Scheme 2) to yield the following reaction products, viz., 6a,b, 7a,b, and 8 in the ratio ~ 1:3:2 (see Experimental section).
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Scheme 2. Syntheses of 6a,b, 7a,b and 8.
Scheme 2. Syntheses of 6a,b, 7a,b and 8.
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These compounds were separated by column chromatography on alumina. Eluted first were cyclopropenes 6a (6b). In solid state, they are orange powders that gradually decompose on storage. Their structures were established based on the data from 1H- and 13C-NMR spectroscopy and mass spectrometry. Thus, the corresponding 1H- and 13C-NMR spectra contain the necessary number of signals for the protons and carbon atoms corresponding to the methylene groups of the morpholine and piperidine substituents and to two ferrocenyl fragments. The 13C-NMR spectra also contain the signals for the nitrile groups (6a, δ 120.56 ppm; 6b, δ 121.75 ppm), and the 1H-NMR spectra contain signals at δ = 5.37 and 5.52 ppm, respectively, typical of the -NH group.
Eluted next from the column were compounds 7a and 7b as single isomers, judging from their 1H- NMR spectra. Their structures were established by 1H- and 13C-NMR, IR, and UV spectroscopy. The 1H-NMR spectra of compounds 7a and 7b contain, in addition to the signals for the protons and carbon atoms corresponding to the methylene groups of the morpholine and piperidine substituents and to two ferrocenyl fragments, one singlet each for low-field protons at δ 6.45 ppm (7a) and δ 6.39 ppm (7b), which allowed assigning them tentative structures of 3-morpholino-3-(cyanoimino)- and 3-piperidino-3-(cyanoimino)-1,2-diferrocenylprop-1-enes 7a and 7b, respectively. The structure of compound 7a followed also from X-ray diffraction analysis of a single crystal prepared by crystallization from dichloromethane [22], which proved its structure as Z-3-morpholino-3-(cyanoimino)-1,2-diferrocenyl-prop-1-ene. The general view of the molecule 7a is shown in Figure 2a, the packing of molecules in a crystal is shown in Figure 2b, and the main geometrical parameters are given in Table 1. Data from the X-ray analysis show that the N=C bond in the azadiene is somewhat longer [d = 1.314(3) Å] than the standard value of 1.29 Å [23,24]. The lengths of C-Fe and C-C bonds in the ferrocenyl substituents are close to the standard values [25]. By analogy, the structure of Z-3-piperidino-3-(cyanoimino)-1,2-diferrocenylprop-1-ene was ascribed to compound 7b.
Eluted last from the chromatographic column was 3-cyanoimino-1,2-diferrocenylcyclopropene (8). It is possibly the pseudoaromatic character of these structures (A↔B) (Scheme 3) that determines this order of elution.
Table
Table 1. Selected bond lengths and bond angles for compounds 7a and 10.
Table 1. Selected bond lengths and bond angles for compounds 7a and 10.
Selected bond lengths (Å)Selected bond angles (o)
7a
C(24)-N(2)1.151(4)N(2)-C(24)-N(1)172.6(3)
C(24)-N(1)1.329(4)C(23)-N(1)-C(24)119.3(2)
C(23)-N(1)1.314(3)N(1)-C(23)-N(3)117.5(2)
C(23)-C(22)1.495(3)N(1)-C(23)-C(22)123.2(2)
C(22)-C(21)1.334(3)C(23)-C(22)-C(21)118.8(2)
C(23)-N(3)1.332(3)C(22)-C(23)-N(3)119.3(2)
N(3)-C(25)1.454(4)C(21)-C(22)-C(11)123.0(2)
C(1)-C(21)1.462(3)C(23)-N(3)-C(27)121.4(3)
10
N(1)-C(25)1.338(6)C(21)-N(1)-C(25)120.1(4)
N(2)-C(25)1.145(6)N(2)-C(25)-N(1)172.1(5)
C(21)-N(1)1.303(5)N(1)-C(21)-C(22)122.7(3)
C(21)-C(22)1.499(5)C(21)-C(22)-C(23)115.8(3)
C(22)-C(23)1.350(5)C(22)-C(23)-S(1)126.9(3)
C(23)-S(1)1.739(4)C(23)-S(1)-C(24)100.6(2)
S(1)-C(24)1.789(5)N(1)-C(21)-C(1)118.5(4)
C(22)-C(11)1.459(5)C(1)-C(21)-C(22)118.8(3)
C(1)-C(21)1.442(5)C(11)-C(22)-C(23)127.8(3)
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Figure 2. (a) Crystal structure of 7a; (b) Crystal packing of 7a.
Figure 2. (a) Crystal structure of 7a; (b) Crystal packing of 7a.
Molecules 14 03161 g011
Molecules 14 03161 g003 550
Scheme 3. Pseudoaromatic character of 3-cyanoimino-1,2-diferrocenylcyclopropene 8.
Scheme 3. Pseudoaromatic character of 3-cyanoimino-1,2-diferrocenylcyclopropene 8.
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The cationic part of this structure is cyclopropenylium with the Hückel aromaticity [26,27], which makes the contribution of structure B quite important [7]. Spectroscopic characteristics of cyclopropene 8 corroborate its structure.
We also found that the reactions of diferrocenylcyclopropenylium salts 5a (5b) with sodium cyanamide carried out in boiling acetonitrile (10-12 h) afforded compounds 7a (7b) and 8. The same products were formed upon prolonged boiling of cyclopropenes 6a (6b) in acetonitrile (Scheme 4).
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Scheme 4. Synthesis of 7a, 7b and 8.
Scheme 4. Synthesis of 7a, 7b and 8.
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It thus follows that azadienes 7a (7b) and cyanoiminocyclopropene 8 result from transformations of tetrasubstituted diferrocenylcyclopropenes 6a (6b). A plausible mechanism of the reaction includes initial nucleophilic attack of the cyanamide anion on the C-1 atom of the three-membered ring of cyclopropenylium cations 5a (5b) with formation of 3-cyanoamino-1,2-diferrocenyl-3-morpholino- (or -3-piperidino)cyclopropenes 6a (6b) (Scheme 5).
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Scheme 5. Plausible mechanism of the formation of 6a, 6b and 8.
Scheme 5. Plausible mechanism of the formation of 6a, 6b and 8.
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Subsequent intramolecular transformation of tetrasubstituted cyclopropenes 6a (6b) with elimination of a molecule of morpholine (piperidine) (Scheme 6) affords cyanoiminocyclopropene 8. Compounds 6a (6b) undergo also three-membered ring opening [16,17,18,19] giving cyanoamino-diferrocenyl(morpholino)- or [-(piperidino)]vinylcarbenes 9a (9b), which are stabilized as a result of proton migration (Scheme 6).
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Scheme 6. Plausible mechanism of the formation of 7a and 7b.
Scheme 6. Plausible mechanism of the formation of 7a and 7b.
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Unlike cyclopropenylium salts 5a (5b), diferrocenyl(methylthio)cyclopropenylium iodide (2) reacts with sodium cyanamide at 20 ºC to yield mainly two products, 10 and 8, and small amounts of cyclopropenes 11a and 11b (Scheme 7).
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Scheme 7. Synthesis of 10, 11a and 11b.
Scheme 7. Synthesis of 10, 11a and 11b.
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The physicochemical characteristics of compound 8 were identical to those of the product prepared from diferrocenyl(morpholino)- and -(piperidino)cyclopropenylium salts 5a and 5b. The structure of compound 10 was established based on the data from IR, UV, 1H- and 13C-NMR spectroscopy and mass spectrometry. The structure of compound 10 was also confirmed by X-ray diffraction analysis of a single crystal prepared by crystallization from chloroform [22]. The perspective view of the molecule 10 is shown in Figure 3a, the crystal packing diagram is shown in Figure 3b, and selected bond lengths and bond angles are listed in Table 1.
According to the data from X-ray analysis, compound 10 is Z-3-cyanoimino-2,3-diferrocenyl-1-methylthioprop-1-ene. The length of the N=C bond in compound 10 [d = 1.303(5) Å] is somewhat longer than the standard value of 1.29 Å [23,24].
In our opinion, the fact that the N=C bond in compounds 7a and 10 is longer than the standard value of 1.29 Å is due to the presence of a conjugated system of double bonds in these compounds. In addition, it can be observed from Table 1 that σ-bonds in these compounds are somewhat shorter than the corresponding standard values. We think that the latter observation is also due to the presence of the conjugated system of bonds.
Isomeric 3-cyanoamino(diferrocenyl)cyclopropenes 11a and 11b (yields ~10 and 6%, respectively) are unstable oily products that undergo rapid decomposition on storage under ordinary conditions. Their structures were established based on the data from IR, 1H- and 13C-NMR spectroscopy and mass spectrometry. Structures 11a and 11b were assigned to the isomers of methylthiocyclopropenes based on the position of the proton signals of the substituted cyclopentadiene rings in the 1H NMR spectra. In cyclopropene 11a, all signals for the protons of the C5H4 fragments are present in a lower field than the singlets of the protons of unsubstituted cyclopentadienyl groups. In cyclopropene 11b, the signals for the protons of one of the C5H4 fragments of the ferrocenyl substituent are upfield relative to the signals for the protons of the C5H5 group, which corresponds to the effect of electron-donating MeS-C=C-Fc fragment of the cyclopropene.
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Figure 3. (a) Crystal structure of 10; (b) Crystal packing of 10.
Figure 3. (a) Crystal structure of 10; (b) Crystal packing of 10.
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Obviously, one of the reaction products of iodide 2 with sodium cyanamide, viz., cyanoiminocyclopropene 8, results from intramolecular transformation of cyclopropene 11a (Scheme 8) analogous to that of 3-cyanoamino-1,2-diferrocenyl-3-morpholino- ( or -3-piperidino)cyclopropenes 6a (6b) (see Scheme 5). The other reaction product, compound 10, is formed upon three-membered ring opening [16,17,18,19] in 3-cyanoamino-2,3-diferrocenyl-1-methylthiocyclopropene 11b to vinylcarbene 9c, whose stabilization owing to the proton transfer to the carbine center affords azadiene 10 (Scheme 8).
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Scheme 8. Plausible mechanism of the formation of 8 and 10.
Scheme 8. Plausible mechanism of the formation of 8 and 10.
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The results obtained demonstrate different effects of the heterosubstituents on the regioselectivities of reactions of morpholino- (or piperidino-) and methylthio-diferrocenylcyclopropenylium salts with the cyanamide anion and on relative stabilities, i.e., proneness to opening of their three-membered rings. The reaction products of salts 5a,b are formed exclusively upon the attack of the cyanamide anion on the C-1 atom of the cyclopropenylium ring. Such a regioselectivity is uncharacteristic of the reaction of the 1-methylthio- analog; at the same time, transformations of tetrasubstituted cyclopropene intermediates 11a and 11b occur much more smoothly.
Further, we observed that 3-cyanoimino-1,2-diferrocenylcyclopropene (8) as a pseudoaromatic compound reacts with hydrazine in boiling ethanol to give two reaction products, viz., compounds 12 and 13 (Scheme 9). The nucleophilic attack of the hydrazine nitrogen atom on the carbon atom of the nitrile group results in 3-amino-6-ferrocenyl-5-ferrocenylmethyl-1,2,4-triazine (12) via tentative intermediates 14, 15, and 16. The structure of compound 12 was established by IR, 1H- and 13C-NMR spectroscopic and mass spectrometric data. Thus the IR spectrum of compound 12 contains absorption bands of a free NH2 group (ν 3487 cm-1) and ferrocenyl substituents. The 1H-NMR spectrum contains signals for protons of two ferrocene fragments, a singlet of an FcCH2 group (δ 4.32 ppm) and a broad singlet of protons of the NH2 group (δ 6.94 ppm). Data from the 13C-NMR spectrum corroborate the structure of compound 12.
The nucleophilic attack of hydrazine on the C-1 atom of the three-membered ring in 8B affords product 13 resulting from opening of the small ring in intermediate 17 to vinylcarbene 18 and its subsequent intramolecular transformation; the structure of the final product 13 followed from the spectroscopic data.
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Scheme 9. Plausible mechanism of reaction of 3-cyanoimino-1,2-diferrocenyl-cyclopropene 8 with hydrazine.
Scheme 9. Plausible mechanism of reaction of 3-cyanoimino-1,2-diferrocenyl-cyclopropene 8 with hydrazine.
Molecules 14 03161 g009

Experimental

General

All the solvents were dried according to the standard procedures and were freshly distilled before use [28]. Column chromatography was carried out on alumina (Brockmann activity III). The 1H- and 13C-NMR spectra were recorded on a Unity Inova Varian spectrometer (at 300 and 75 MHz, respectively) for solutions in CDCl3, with Me4Si as the internal standard; chemical shifts δ are given in ppm. The IR spectra were measured on a Perkin Elmer FT-IR spectrophotometer (Spectrum RXI) using KBr pellets. The mass spectra were obtained on a Varian MAT CH-6 instrument (EI MS, 70 eV). Elementar Analysensysteme LECO CHNS-900 was used for elemental analyses. The unit cell parameters and the X-ray diffraction intensities were recorded on a Siemens P4 diffractometer. The structures of compounds 7a and 10 were solved by the direct method (SHELXS -97 [29]) and refined using full-matrix least-squares on F2.

Synthesis of diferrocenylcyclopropenylium salts (5a, 5b, and 2)

Diferrocenylcyclopropenylium salts 5a, 5b, and 2 were prepared from 2,3-diferrocenylcyclopropenone as described earlier [16,20,21]: 2,3-diferrocenylcyclopropenone was obtained from the ferrocene and tetrachlorocyclopropene in the presence of AlCl3 according to the standard procedure [20]; Ethoxy(diferrocenyl)cyclopropenylium tetrafluoroborate was obtained from 2,3-diferrocenylcyclopropenone in the presence of triethyl-oxonium tetrafluoroborate (1.0 M solution in dichloromethane) [21]; Morpholino- and piperidino-(differocenyl)cyclopropenylium tetrafluoroborates were obtained from ethoxy(diferrocenyl)-cyclopropenylium tetrafluoroborate and morpholine or piperidine in dichloromethane [21]; 3-Diferrocenylcyclopropenethione was obtained by treating ethanolic differocenyl(morpholino)-cyclopropenylium tetrafluoroborate with an aqueous solution of NaSH [16]; 2,3-Diferrocenyl-(methylthio)cyclopropenylium iodide (2) was obtained from the 2,3-diferrocenylcyclopropenethione and iodomethane [16]. Freshly prepared and thoroughly dried tetrafluoroborates 5a,b and iodide 2 were employed in the reactions with sodium hydrogencyanamide. Reactions were carried out in freshly distilled dry solvents.

Reaction of dialkylamino(diferrocenyl)cyclopropenylium tetrafluoroborates with sodium hydrogencyanamide

Sodium hydrogencyanamide (0.64 g, 10 mmol) was added to a solution of 1-amino-2,3-diferrocenylpropenylium tetrafluoroborate 5a, b (5 mmol) in dichloromethane (chloroform, acetone, or acetonitrile) (100 mL), and the mixture was stirred in a dry inert atmosphere at ~20 °C (~24-36 h) or under reflux (14-20 h). The solvents were removed in vacuo, and the residues were chromatographed on alumina (hexane-dichloromethane, 4:1) to give compounds 6a, b, 7a, b and 8.
3-Cyanoamino-1,2-diferrocenyl-3-morpholinocyclopropene (6a): Yield 0.32 g (12%); red-violet powder; mp 174-175 °C; 1H-NMR: δ 3.16 (m, 4H, 2CH2), 3.56 (m, 4H, 2CH2), 4.09 (s, 5H, C5H5), 4.24 (s, 5H, C5H5), 4.05 (m, 2H, C5H4), 4.15 (m, 1H, C5H4), 4.43 (m, 1H, C5H4), 4.68 (m, 2H, C5H4), 5.01 (m, 2H, C5H4), 5.37 (bs, 1H, NH); 13C-NMR: δ 61.23 (C), 65.21 (2CH2), 66.34 (2CH2), 69.24, 70.43 (2C5H5), 67.93, 68.05, 69.04, 69.37, 70.82, 71.10, 72.34, 72.47 (2C5H4), 80.22, 81.23 (2CipsoFc), 120.56 (CN), 139.11 (2C); MS: m/z 533 [M]+; Anal. Calcd. for C28H27Fe2N3O: C, 63.07; H, 5.10; Fe, 20.95; N, 7.88; Found: C, 62.91; H, 5.17; Fe, 21.06; N, 7.69.
Z-3-morpholino-3-(cyanoimino)-1,2-diferrocenylprop-1-ene (7a): Yield 1.01 g (37%); violet crystals; mp 229-230 °C; λmax (CHCl3, 20oC): 207.31, 207.80, 235.05, 235.55 nm; IR (KBr): 473, 483, 541, 723, 773, 824, 861, 898, 921, 930, 977, 1000, 1024, 1052, 1105, 1115, 1214, 1259, 1286, 1324, 1352, 1383, 1411, 1440, 1484, 1536, 1626, 2181, 2851, 2977, 3082 cm-1;1H-NMR: δ 3.48-3.92 (m, 8H, 4CH2), 4.27 (s, 5H, C5H5), 4.29 (s, 5H, C5H5), 4.04 (m, 1H, C5H4), 4.22 (m, 1H, C5H4), 4.25 (m, 1H, C5H4), 4.28 (m, 1H, C5H4), 4.32 (m, 1H, C5H4), 4.34 (m, 1H, C5H4), 4.41 (m, 1H, C5H4), 4.82 (m, 1H, C5H4), 6.45 (s, 1H, CH=); 13C-NMR: δ 66.22 (2CH2), 66.52 (2CH2), 69.53, 69.74 (2C5H5), 67.98, 68.15, 68.88, 68.95, 69.12, 70.01, 70.25, 71.29 (2C5H4), 78.18, 80.28 (2CipsoFc), 126.07 (CN), 133.89 (CH=), 144.27 (C), 169.78 (C=N); MS: m/z 533 [M]+; Anal. Calcd. for C28H27Fe2N3O: C, 63.07; H, 5.10; Fe, 20.95; N, 7.88; Found: C, 63.19; H, 4.98; Fe, 20.87; N, 7.99.
3-Cyanoimino-1,2-diferrocenylcyclopropene (8): Yield 0.56 g (25%); orange crystals; mp 214-216 °C; IR (KBr): 472, 483, 540, 551, 558, 722, 772, 824, 861, 898, 920, 930, 977, 1000, 1024, 1052, 1104, 1115, 1214, 1258, 1286, 1323, 1352, 1381, 1411, 1439, 1494, 1534, 1626, 1864, 2179, 2850, 2892, 2977, 3082 cm-1; 1H-NMR: δ 4.28 (s, 10H, 2C5H5), 4.71 (m, 4H, C5H4), 4.93 (m, 4H, C5H4); 13C-NMR: δ 70.48 (2C5H5), 72.65, 73.31, 73.35, 73.38 (2C5H4), 88.36, 88.64 (2CipsoFc), 121.28 (CN), 132.64 (C), 145.51 (C=N); MS: m/z 446 [M]+; Anal. Calcd. for C24H18Fe2N2: C, 64.62; H, 4.06; Fe, 25.04; N, 6.28; Found: C, 64.51; H, 4.12; Fe, 24.89; N, 6.19.
3-Cyanoamino-1,2-diferrocenyl-3-piperidinocyclopropene (6b): Yield 0.38 g (14%); red-violet powder; mp 172-173 °C; 1H-NMR: δ 1.58 (m, 2H, CH2), 1.74 (m, 4H, 2CH2), 2.99-3.06 (m, 4H, 2CH2), 4.05 (s, 5H, C5H5), 4.21 (s, 5H, C5H5), 3.99 (m, 1H, C5H4), 4.03 (m, 2H, C5H4), 4.55 (m, 1H, C5H4), 4.63 (m, 1H, C5H4), 4.71 (m, 2H, C5H4), 5.10 (m, 1H, C5H4), 5.52 (bs, 1H, NH); 13C-NMR: δ 23.95 (CH2), 25.64 (2CH2), 50.31 (2CH2), 58.19 (C), 69.31, 70.52 (2C5H5), 68.04, 68.12, 69.29, 69.42, 71.02, 72.13, 72.85, 72.90 (2C5H4), 81.35, 81.41 (2CipsoFc), 121.75 (CN), 139.24 (2C); MS: m/z 531 [M]+; Anal. Calcd. for C29H29Fe2N3: C, 65.56; H, 5.50; Fe, 21.03; N, 7.91; Found: C, 65.63; H, 5.38; Fe, 21.15; N, 7.99.
Z-3-Piperidino-3-(cyanoimino)-1,2-diferrocenylprop-1-ene (7b): Yield 1.20 g (45%); violet crystals; mp 195-196 °C; λmax (CHCl3, 20oC): 205.96, 207.43, 233.82, 237.03 nm; IR (KBr) 472, 481, 540, 722, 773, 822, 860, 896, 920, 930, 978, 1000, 1024, 1050, 1103, 1114, 1213, 1259, 1287, 1321, 1352, 1384, 1412, 1441, 1485, 1536, 1626, 2180, 2852, 2975, 3082 cm-1; 1H-NMR: δ 1.73-1.92 (m, 6H, 3CH2), 3.15-3.72 (m, 4H, 2CH2), 4.22 (s, 5H, C5H5), 4.23 (s, 5H, C5H5), 4.05 (m, 1H, C5H4), 4.12 (m, 1H, C5H4), 4.17 (m, 1H, C5H4), 4.20 (m, 1H, C5H4), 4.21 (m, 1H, C5H4), 4.30 (m, 1H, C5H4), 4.36 (m, 1H, C5H4), 4.78 (m, 1H, C5H4), 6.39 (s, 1H, CH=); 13C-NMR: δ 24.05, 25.38, 26.32, 45.19, 49.85 (5CH2), 69.42, 69.63 (2C5H5), 67.92, 68.01, 68.64, 68.99, 69.09, 69.78, 70.62, 70.89 (2C5H4), 78.40, 80.92 (2CipsoFc), 126.07 (CN), 133.0 (CH=), 135.52 (C), 152 46 (C=N); MS: m/z 531 [M]+; Anal. Calcd. for C29H29Fe2N3: C, 65.56; H, 5.50; Fe, 21.03; N, 7.91; Found: C, 65.39; H, 5.61; Fe, 21.18; N, 7.79.
3-Cyanoimino-1,2-diferrocenylcyclopropene (8): Yield 0.57 g (26%); orange crystals; mp 214-216 °C.

Reaction of 2,3-diferrocenyl-1-methylthiocyclopropenylium iodide (2) with sodium hydrogencyanamide

A solution of compound 2 (2.9 g, 5.0 mmol) in dichloromethane (chloroform, acetone, or acetonitrile) (100 mL) was stirred with sodium hydrogencyanamide (0.64 g, 10 mmol) at ~20 °C (9-12 h) or under reflux for 5 h. Subsequent work-up of the reaction mixtures as described above gave compounds 8, 10 and 11a,b.
3-Cyanoimino-1,2-diferrocenylcyclopropene (8): Yield 0.18 g (8%); orange crystals; mp 215-216 °C.
Z-3-Cyanoimino-2,3-diferrocenyl-1-methylthioprop-1-ene (10): Yield 1.51 g (61%); violet crystals; mp 183-184 °C; λmax (CHCl3, 20oC): 245.09, 299.36, 299.70, 368 nm; IR (KBr): 474, 495, 540, 613, 677, 723, 774, 818, 829, 866, 889, 1000, 1030, 1048, 1106, 1123, 1216, 1295, 1304, 1338, 1376, 1408, 1432, 1464, 1517, 1567, 1635, 2178, 2919, 3103 cm-1; 1H-NMR: δ 2.59 (s, 3H, CH3), 4.20 (s, 5H, C5H5), 4.28 (s, 5H, C5H5), 4.25 (m, 2H, C5H4), 4.30 (m, 2H, C5H4), 4.48 (m, 1H, C5H4), 4.62 (m, 2H, C5H4), 5.05 (m, 1H, C5H4), 6.71 (s, 1H, CH=); 13C-NMR: δ 18.87 (CH3), 69.83, 70.92 (2C5H5), 68.32, 68.74, 73.27, 73.68 (2C5H4), 93.22, 99.91 (2CipsoFc), 121.15 (CH=), 123.07 (CN), 132.48 (C), 155 91 (C=N); MS: m/z 494 [M]+; Anal. Calcd. for C25H22Fe2N2S: C, 60.36; H, 4.50; Fe, 22.60; N, 5.66; S, 6.43; Found: C, 60.48; H, 4.33; Fe, 22.54; N, 5.72; S, 6.57.
3-Cyanoamino-1,2-diferrocenyl-3-methylthiocyclopropene (11a): Yield 0.25 g (10%); red-violet powder; mp 163-164 °C; 1H-NMR: δ 2.48 (s, 3H, CH3), 4.18 (s, 5H, C5H5), 4.19 (s, 5H, C5H5), 4.36 (m, 2H, C5H4), 4.45 (m, 1H, C5H4), 4.58 (m, 1H, C5H4), 4.69 (m, 1H, C5H4), 4.70 (m, 2H, C5H4), 4.91 (m, 1H, C5H4), 5.08 (bs, 1H, NH); 13C-NMR: δ 16.23 (CH3), 58.52 (C), 69.59, 70.13 (2C5H5), 68.57, 68.86, 69.42, 70.45 (2C5H4), 85.41, 87.74 (2CipsoFc), 122.83 (CN), 126.95, 133.21 (2C); MS: m/z 494 [M]+; Anal. Calcd. for C25H22Fe2N2S: C, 60.36; H, 4.50; Fe, 22.60; N, 5.66; S, 6.43; Found: C, 60.42; H, 4.37; Fe, 22.73; N, 5.47; S, 6.58.
3-Cyanoamino-2,3-diferrocenyl-1-methylthiocyclopropene (11b): Yield 0.15 g (6%); red-violet powder; mp 158-159 °C; 1H-NMR: δ 2.62 (s, 3H, CH3), 4.07 (s, 5H, C5H5), 4.11 (s, 5H, C5H5), 4.01 (m, 2H, C5H4), 4.09 (m, 2H, C5H4), 4.18 (m, 2H, C5H4), 4.23 (m, 2H, C5H4), 5.31 (bs, 1H, NH); 13C- NMR δ 17.4 (CH3), 63.14 (C), 69.46, 69.75 (2C5H5), 68.41, 68.54, 68.92, 70.04 (2C5H4), 80.01, 82.91 (2CipsoFc), 125.24 (CN), 127.13, 131.84 (2C); MS: m/z 494 [M]+; Anal. Calcd. for C25H22Fe2N2S: C, 60.36; H, 4.50; Fe, 22.60; N, 5.66; S, 6.43; Found: C, 60.21; H, 4.67; Fe, 22.51; N, 5.72; S, 6.35.

Reaction of 3-cyanimino-1,2-diferrocenylcyclopropene (8) with hydrazine

A solution of compound 8 (1.0 mmol) and hydrazine hydrate (2.0 mL) in ethanol (20 mL) was stirred for 6 h at 78 °C. The reaction mixture was evaporated in vacuo, and residue was chromatographed (Al2O3; hexane/ethyl ether, 4:1) to give compounds 12 and 13.
3-Amino-6-ferrocenyl-5-ferrocenylmethyl-1,2,4-triazine (12): Yield 0.17g (35%); orange powder; mp 236-238 °C; IR (KBr) 487, 534, 718, 821, 89, 934, 1002, 1038, 1101, 1123, 1171, 1244, 1302, 1360, 1456, 1507, 1586, 1599, 1612, 1651, 2890, 2934, 3091, 3421 cm-1; 1H-NMR: δ 4.12 (s, 5H, C5H5), 4.24 (s, 5H, C5H5), 4.29 (m, 2H, C5H4), 4.31 (m, 2H, C5H4), 4.34 (m, 2H, C5H4), 4.45 (m, 2H, C5H4), 4.32 (s, 2H, CH2), 6.94 (bs, 2H, NH2); 13C-NMR: δ 57.93 (CH2), 69.57, 70.18 (2C5H5), 68.93, 69.44, 70.34, 70.98 (2C5H4), 84.88, 90.07 (2CipsoFc), 149.13, 152.36, 156.29 (3C); MS: m/z 478 [M]+; Anal. Calcd. for C24H22Fe2N4: C, 60.29; H, 4.64; Fe, 23.36; N, 11.71; Found: C, 60.41; H, 4.53; Fe, 23.51; N, 11.64.
Z-2,3-Diferrocenylacrylohydrazide N-cyanoimide (13): Yield 0.23 g (48%); violet powder; mp 304-305 °C; IR (KBr) 478, 498, 532, 614, 678, 720, 770, 821, 830, 869, 923, 1001, 1027, 1051, 1103, 1120, 1221, 1297, 1302, 1345, 1369, 1411, 1432, 1469, 1523, 1567, 1634, 2172, 2896, 3093, 3165, 3487 cm-1; 1H-NMR: δ 4.09 (s, 5H, C5H5), 4.14 (s, 5H, C5H5), 4.21 (m, 2H, C5H4), 4.32 (m, 2H, C5H4), 4.39 (m, 2H, C5H4), 4.57 (m, 2H, C5H4), 7.68 (s, 1H, CH=), 8.94 (bs, 3H, NHNH2); 13C-NMR: δ 69.12, 69.2 (2C5H5), 67.56, 67.84, 67.96, 68.32, 68.53, 69.02, 69.32, 69.75 (2C5H4), 86.91, 91.08 (2CipsoFc), 125.47 (CN), 134.21 (CH=), 142.08 (C), 158.51 (C=N); MS: m/z 478 [M]+; Anal. Calcd. for C24H22Fe2N4: C, 60.29; H, 4.64; Fe, 23.36; N, 11.71; Found: C, 60.51; H, 4.70; Fe, 23.21; N, 11.79.

Transformation of 3-dialkylamino-, 3-methylthio-3-cyanamino-1,2-diferrocenylcyclopropenes 6a,b and 11a into 3-cyanimino-1,2-diferrocenylcyclopropene (8)

A solution of the compounds 6a, 6b or 11a (1 mmol) in ethanol (acetonitrile, benzene) (50 mL) was heated at reflux for 6 h and concentrated. The residue was chromatographed on Al2O3 (hexane - dichloromethane, 4:1) to give 0.34 - 0.36 g (75 - 81%) (from 6a), 0.32 - 0.34 g (68 - 76%) (from 6b) or 0.32 - 0.33 g (71 – 73%) (from 11a) of compound 8, mp 214-216 °C.

Transformation of 3-cyanamino-2,3-diferrocenyl-1-methylthiocyclopropene (11b) into Z-3-cyanoimino-2,3-diferrocenyl-1-methylthioprop-1-ene (10)

A solution of cyclopropene 11b (1 mmol) in benzene (50 mL) was heated at reflux for 6 h and concentrated. The residue was chromatographed on Al2O3 (hexane - dichloromethane, 4:1) to give 0.39 g (79%) of compound 10, mp 183-184 °C.

Conclusions

3-Cyanoamino-1,2-diferrocenyl-3-morpholino- (piperidino- or methylthio)cyclopropenes 6a,b, 11a undergo smooth intramolecular transformations with conservation of the three-membered ring affording 3-cyanoimino-1,2-diferrocenylcyclopropene (8). Compounds 6a and 6b also undergo three-membered ring opening giving cyanoaminodiferrocenyl(morpholino)- or -(piperidino)vinylcarbenes 9a (9b) which allows the use of 1,2-diferrocenylpropene fragments in the synthesis of diferrocenylhetero-1,3-diene systems 7a and 7b. 3-Cyanoamino-2,3-diferrocenyl-1-methylthiocyclopropene (11b) is transformed upon three-membered ring opening into Z-3-cyanoimino-2,3-diferrocenyl-1-methylthio-prop-1-ene(10). 3-Cyanoimino-1,2-diferrocenylcyclopropene (8) reacts with hydrazine to form 3-amino-6-ferrocenyl-5-ferrocenylmethyl-1,2,4-triazine (12) and Z-2,3-diferrocenylacrylohydrazide-N-cyanoimide (13) as a result of intramolecular transformations of intermediates 14 and 17 with cyclopropene-ring opening. Thus, the reaction of diferrocenylcyclopropene 8 with hydrazine gives rise to aromatic 1,2,4-trizines with amino substituents in the heterocycle. This novel method of synthesis of 1,2,4-aminotrizines, obviously, requires more detailed studies aimed at extension of its potential for the application in organic synthesis.

Acknowledgements

This work was supported by the DGAPA - UNAM (Mexico, grant IN 214209). Thanks are due to Eduardo Arturo Vázquez López for his technical assistance.
  • Sample Availability: Samples of the compounds 5a,b, 7a,b and 8 are available from the authors.

References and Notes

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MDPI and ACS Style

Klimova, E.I.; Klimova, T.; Flores-Alamo, M.; Backinowsky, L.V.; Garcia, M.M. Intramolecular Transformations of 3-Cyanoamino- and 3-Cyanoimino-1,2-diferrocenylcyclopropenes. Molecules 2009, 14, 3161-3175. https://doi.org/10.3390/molecules14093161

AMA Style

Klimova EI, Klimova T, Flores-Alamo M, Backinowsky LV, Garcia MM. Intramolecular Transformations of 3-Cyanoamino- and 3-Cyanoimino-1,2-diferrocenylcyclopropenes. Molecules. 2009; 14(9):3161-3175. https://doi.org/10.3390/molecules14093161

Chicago/Turabian Style

Klimova, Elena Ivanovna, Tatiana Klimova, Marcos Flores-Alamo, Leon Vladimirovich Backinowsky, and Marcos Martinez Garcia. 2009. "Intramolecular Transformations of 3-Cyanoamino- and 3-Cyanoimino-1,2-diferrocenylcyclopropenes" Molecules 14, no. 9: 3161-3175. https://doi.org/10.3390/molecules14093161

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