ISSN 1070-4280, Russian Journal of Organic Chemistry, 2016, Vol. 52, No. 8, pp. 1118–1120. © Pleiades Publishing, Ltd., 2016. Original Russian Text © V.M. Mokhov, V.V. Burmistrov, G.M. Butov, 2016, published in Zhurnal Organicheskoi Khimii, 2016, Vol. 52, No. 8, pp. 1128–1130.

Chemical Transformations of Tetracyclo[3.3.1.1.3,7.0.1,3]decane (1,3-Dehydroadamantane): I. Reaction of 1,3-Dehydroadamantane with Carboxylic Acids Esters V. M. Mokhova, V. V. Burmistrovb, and G. M. Butovb* a b

Volgograd State Technical University, Volgograd, Russia

Volzhskii Polytechnical Institute branch, ul. Engelsa 42A, Volzhskii, 404121 Russia *e-mail: [email protected] Received April 6, 2016

Abstract—Adamantylation of carboxylic acids esters was performed with 1,3-dehydroadamantane for the first time. The reaction proceeds under mild conditions and can be used as a convenient single stage procedure for the synthesis of esters of branched carboxylic acids having an adamantyl group in the α-position to the carbonyl group.

DOI: 10.1134/S1070428016080042 Development of efficient few stage methods for the functional groups introduction into the adamantane scaffold is an urgent task of organic chemistry. The existing synthetic approaches involve the activation of the nodal position of adamantane. The activation of the С–Н bond is performed in strong acids or oxidative environment where a 1-adamantyl cation is generated. Its reaction with carbon oxide or vinylidene chloride furnishes 1-adamantylcarboxylic and 1-adamantylacetic acids [1]. Further the carboxy groups are utilized in versatile reactions for the synthesis of functional adamantane derivatives: amines, amides, nitriles, esters, etc. [2]. Halo- and hydroxyderivatives of adamantane are used for adamantane functionalization in multistage methods. The application of catalytic systems for the generation of the adamantyl radical and its further reaction with unsaturated compounds not always give good results [3]. Esters of 1-adamantylcarboxylic acids are not only semiproducts for the preparation of functional adamantane derivatives but may find application as components of promising lubricating materials, heat-resistant fluids [4, 5]. The information on the synthesis of esters of α-(1-adamantyl)carboxylic acids are scarce, and their preparation requires multistage processes. Esters of 2-(1-adamantyl)arylacetic or 2-(1-adamantyl)-4-arylbut-2-enoic acids were obtained in 10– 70% yields at the reaction of adamantane with the

corresponding aryl- or vinyl diazoacetates in the presence of rhodium complexes [6, 7]. Another method to synthesize esters of branched adamantylcarboxylic acids consisted in the introduction of alkyl groups in the molecule of esters of 1-adamantylacetic acid by its metalation with butyllithium followed by the reaction with allyl bromide at –60°С [8]. A procedure is described of the preparation of ethyl 2-(1-adamantyl)butyrate from 1-bromoadamantane and 1-(trimethylsiloxy)-2-ethyl-1-ethoxybut-1-ene in the presence of ZnCl2 in dichloromethane at room temperature in a 76% yield [9]. Analogously ethyl 2(1-adamantyl)-2-methylpropanoate was obtained in a 70% yield using 2-methyl-1-methoxy-1-(trimethylsiloxy)prop-1-ene [10]. The addition to unsaturated compounds of an adamantyl radical formed from 1bromoadamantane in the presence of Bu3SnH and АIBN resulted in esters of branched carboxylic acids including an adamantyl scaffold [3]. Therefore the existing procedures for the preparation of carboxylic acids esters containing an adamantyl residue require the application of expensive reagents, organometallic compounds, and low temperatures as well. A promising synthon for the preparation of functionalized adamantane derivatives is 1,3-dehydroadamantane (tetracyclo[3.3.1.1.3,7.0.1,3]decane) 1, a

1118

CHEMICAL TRANSFORMATIONS OF TETRACYCLO[3.3.1.1.3,7.0.1,3]DECANE...

+

1

R1

O

R2

O

1119

O O R1

2a_2f

R2 3a_3f

R1 = H, R2 = Me (a), Et (b), Pr (c), Ph (e), C10H7 (f); R1 = R2 = Me (d).

specimen from the class of [3.3.1]propellanes. We formerly carried out direct adamantylation reactions of ketones [11], ketoesters [12], β-dicarbonyl compounds [13, 14] utilizing propellane 1 as an alkylating agent in a wide range of the СН-acidity of the substrate. The reactions occurred mainly in the α-position with respect to the carbonyl group affording the corresponding adamantane derivatives in 55–98% yields. At the use of highly acidic substrates, e.g., β-dicarbonyl compounds with trifluoromethyl groups, the reaction proceeded quickly and in mild conditions [14]. The obtained data suggested that the reaction occurred through the stages of the СН-acid dissociation, the attack of a proton on the С–Н bond of propellane 1, and recombination of the intermediately formed 1-adamantyl cation with the anionic residue of the СН-acid. Esters of monocarboxylic acids do not belong to strong СН-acid, for instance, in water at 25°С pKа of ethyl acetate is 26 [15]. Therefore the direct adamantylation of the С–Н bond in the α-position of weak acids esters should proceed under more rigid conditions. As initial esters we used ethyl esters of aliphatic carboxylic (propionic 2a, butyric 2b, isobutyric 2c, valeric 2d) and aliphatic-aromatic (phenyl- and 1naphthylacetic) acids. Reactions of propellane 1 with ethyl esters of aliphatic carboxylic acids 2a–2d were carried out at elevated temperature (80–100°С) without solvent within 4–6 h to obtain ethyl esters of α-(1-adamantyl)substituted acids 3а–3d in 64–90% yields. Esters 3a–3d were purified by distillation in a vacuum. The purity of esters 3a–3d was checked by GC-MS method. Esters 3a–3d were viscous fluids crystallizing at prolong storage to form low-melting white crystals. It was expected that introducing electron-acceptor groups to the carbon atom linked to the ester group would increase the lability of the methylene group proton thus facilitating the alkylation with propellane 1.

We chose ethyl esters of phenyl- and α-naphthylacetic acid 2е and 2f. Reactions were carried out in the environment of initial esters at 60 (2e) or 70–80°С (2f) for 4 h. Esters of aromatic carboxylic acids 3e and 3f were purified by distillation in a vacuum, their yields were 90 and 73% respectively. Thus we developed a synthetic method of few stages for the synthesis of esters of α-(1-adamantyl) carboxylic and arylcarboxylic acids. The majority of the synthesized esters are difficult to obtain since the main method of their preparation is the esterification with the alcohols of the corresponding adamantylsubstituted acids or their chlorides [16, 17]. Esters 3a– 3f may serve as initial compounds for the preparative synthesis of the corresponding carboxylic acids. EXPERIMENTAL 1

Н NMR spectra were registered on a spectrometer Varian Mercury-300 (operating frequency 300 МHz), solvent tetrachloromethane, internal reference HMDS. GC-MS measurements were performed on an instrument Saturn 2100 T/GC3900 (Varian). Mass spectra were recorded on a GC-MS instrument Agilent GC 7820A/MSD 5975 Series. Ethyl 2-(1-adamantyl)propanoate (3а). A mixture of 20 g (0.196 mol) of ethyl propionate 2а and 2 g (0.015 mol) of propellane 1 was heated for 6 h at 80– 85°С. Excess ethyl propionate was distilled off, the residue was distilled in a vacuum. Yield 2.4 g (0.01 mol, 64%), bp 128–129°С (4 mmHg), nD20 1.5132. 1Н NMR spectrum, δ, ppm: 0.92 t (3Н, СН3, J 13.7 Hz), 1.22 t (3Н, СН3, J 14.0 Hz), 1.54–1.80 m (15Н, 1-Ad), 2.31 m (1Н, СНСО), 3.95–4.10 m (2Н, ОСН2). Found, %: С 76.28; Н 10.18. C15H24О2. Calculated, %: С 76.23; Н 10.24. Compounds 3b–3f were similarly obtained. Ethyl 2-(1-adamantyl)butanoate (3b) was obtained from 24 g (0.21 mol) of ethyl butyrate 2b and 2 g

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016

1120

MOKHOV et al.

(0.015 mol) of propellane 1 within 6 h at 95–100°С. Yield 3.0 g (0.012 mol, 76%), bp 133–135°С (3 mmHg), nD20 1.5102. 1Н NMR spectrum, δ, ppm: 0.80 t (3Н, СН3, J 12.6 Hz), 1.10 t (3Н, СН3, J 13.8 Hz), 1.50– 1.74 m (12Н, 1-Ad, 2Н, СН2), 1.76 s (3Н, 1-Ad), 2.09 m (1Н, СНСО), 3.96–4.12 m (2Н, ОСН2). Mass spectrum (EI, 70 eV), m/z (Irel, %): 250 [M]+ (7), 221 [M – C2H5]+ (1), 202 [M – ОC2H5]+ (1), 135 [Ad]+ (100), 93 (25), 79 (26). Found, %: С 76.80; Н 10.41. C16H26О2. Calculated, %: С 76.75; Н 10.47. M 250.38. Ethyl 2-(1-adamantyl)pentanoate (3c) was obtained from 20 g (0.154 mol) of ethyl valerate 2b and 2 g (0.015 mol) of propellane 1 within 6 h at 80–85°С. Yield 2.4 g (0.01 mol, 64%), bp 142–143°С (3 mmHg), nD20 1.5080. 1Н NMR spectrum, δ, ppm: 0.78 t (3Н, СН3, J 12.8 Hz), 1.12 t (3Н, СН3, J 13.7 Hz), 1.50– 1.74 m (12Н, 1-Ad, 4Н, 2СН2), 1.76 s (3Н, 1-Ad), 2.10 m (1Н, СНСО), 3.96–4.12 m (2Н, ОСН2). Found, %: С 77.29; Н 10.64. C17H28О2. Calculated, %: С 76.22; Н 10.67. Ethyl 2-(1-adamantyl)-2-methylpropanoate (3d) was obtained from 20 g (0.172 mol) of ethyl 2-methylpropanoate 2d and 2 g (0.015 mol) of propellane 1 within 6 h at 85–90°С. Yield 2.7 g (0.011 mol, 72%), bp 130–132°С (4 mmHg), nD20 1.5142. 1Н NMR spectrum, δ, ppm: 1.00 m (6Н, 2СН3), 1.12 t (3Н, СН3, J 9.8 Hz), 1.53–1.75 m (12Н, 1-Ad), 1.92 s (3Н, 1Ad), 4.28–4.34 m (2Н, ОСН2). Found, %: С 76.71; Н 10.44. C16H26О2. Calculated, %: С 76.75; Н 10.47. Ethyl (1-adamantyl)(phenyl)acetate (3e) was obtained from 10 g (0.061 mol) of ethyl phenylacetate 2e and 2 g (0.015 mol) of propellane 1 in 4 h at 55–60°С. Yield 4.1 g (0.014 mol, 91%), bp 175–177°С (2 mmHg), mp 59–60°С. Mass spectrum, m/z (Irel, %): 298 (14) [M]+, 225 (28) [Ad – CH – Ph]+, 135 (100) [Ad]+. 1Н NMR spectrum, δ, ppm: 1.11 t (3Н, СН3, J 14 Hz), 1.51–1.86 m (12Н, 1-Ad), 2.05 s (3Н, 1-Ad), 3.06 s (1Н, СНСО), 3.78–4.14 m (2Н, ОСН2), 7.05–7.22 m (5Н, С6Н5). Found, %: С 80.54; Н 8.77. C20H26О2. Calculated, %: С 80.50; Н 8.78. Ethyl (1-adamantyl)(1-naphthyl)acetate (3f) was obtained from 10 g (0.047 mol) of ethyl α-naphthylacetate 2f and 2 g (0.015 mol) of propellane 1 in 4 h at 70–80°С. Yield 3.73 g (0.011 mol, 73%), bp 210–212°С (1 mmHg), mp 42–45°С. 1Н NMR spectrum, δ, ppm: 1.20 t (3Н, СН3, J 13.6 Hz), 1.46–1.87 m (12Н, 1-Ad), 2.10 s (3Н, 1-Ad), 3.12 s (1Н, СНСО), 3.88–4.18 m (2Н, ОСН2), 7.90–8.20 m (7Н, С10Н7). Found, %:

С 82.72; Н 8.06. C24H28О2. Calculated, %: С 82.72; Н 8.10. The study was carried out under the financial support of the Council for grants of the President of the Russian Federation (Program of the State Support for Young Candidates of Sciences, project no. MK5809.2015.3). REFERENCES 1. Bott, K., Chem. Ber., 1968, vol. 101, p. 564. 2. Wanka, L., Iqbal, K., and Schreiner, P.R., Chem. Rev., 2013, vol. 113, p. 3516. 3. Ohno, M., Itoh, M., Umeda, M., Furuta, R., Kondo, K., and Eguchi, Sh., J. Am. Chem. Soc., 1996, vol. 118, p. 7075. 4. Ivleva, E.A., Baimuratov, M.R., Zhuravleva, Yu.A., Klimochkin, Yu.N., Kulikova, I.A., Pozdnyakov, V.V., Sheikina, N.A., Tyshchenko, V.A., and Rudyak, K.B., Pet. Chem., 2015, vol. 55, p. 133. 5. Ivleva, E.A., Baimuratov, M.R., Gavrilova, V.S., Zhuravleva, Yu.A., Klimochkin, Yu.N., Kulikova, I.A., Pozdnyakov, V.V., Sheikina, N.A., Tyshchenko, V.A., and Rudyak, K.B., Pet. Chem., 2015, vol. 55, p. 673. 6. Reddy, R.P., Lee, G.H., and Davies, H.M.L., Org. Lett., 2006, vol. 8, p. 3437. 7. Davies, H.M.L., Hansen, T., and Churchill, M.R., J. Am. Chem. Soc., 2000, vol. 122, p. 3063. 8. Pour, M., Spulak, M., Balsanek, V., Kunes, J., Kubanova, P., and Buchta, V., Bioorg. Med. Chem., 2003, vol. 11, p. 2843. 9. Reetz, M.T., Schwellnus, K., Huebner, F., Massa, W., and Schmidt, R.E., Chem. Ber., 1983, vol. 116, p. 3708. 10. Reetz, M.T. and Schwellnus, K., Tetrahedron Lett., 1978, vol. 17, p. 1455. 11. No, B.I., Butov, G.M., Mokhov, V.M., and Parshin, G.Yu., Russ. J. Org. Chem., 2002, vol. 38, p. 295. 12. No, B.I., Butov, G.M., Mokhov, V.M., and Parshin, G.Yu., Russ. J. Org. Chem., 2003, vol. 39, p. 1668. 13. Butov, G.M., Mokhov, V.M., Parshin, G.Yu., Kunaev, R.U., Shevelev, S.A., Dalinger, I.L., and Vatsadze, I.A., Russ. J. Org. Chem., 2008, vol. 44, p. 1157. 14. Butov, G.M., Parshin, G.Yu., Kunaev, R.U., and Mokhov, V.M., Izv. VolgGTU, 2007, vol. 5, p. 25. 15. Gordon, A.J. and Ford, R.A., The Chemist's Companion, New York: Wiley–Interscience, 1972; Translated under the title Sputnik khimika, Moscow: Mir, 1976. 16. Sakakura, A., Koshikari, Y., and Ishihara, K., Tetrahedron Lett., 2008, vol. 49, p. 5017. 17. Voelter, W. and Kalbacher, H., Lieb. Ann., 1993, p. 131.

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 8 2016