Reactions of exo-exo -hexacyclo[9.2.1.0 2,10 .0 3,8 .0 4,6 .0 5,9 ]tetradecane with Aliphatic Alcohols under the Action of Ionic Liquids †

: It has been established for the ﬁrst time that ionic liquids catalyze the alcoholysis of a hydrogenated norbornadiene dimer— exo-exo -hexacyclo[9.2.1.0 2,10 .0 3,8 .0 4,6 .0 5,9 ]tetradecane with aliphatic C 1 -C 4 alcohols. The reaction proceeds along the hydrocarbon cyclopropane ring by a regioselective C 4 -C 5 bond cleavage to form the previously undescribed 4-exo -alkoxypentacyclo[8.2.1.1 5,8 .0 2,9 .0 3,7 ] tetradecanes in high yields, which is promising as a precursor for the synthesis of drugs, as well as in the role of transmission media.

On the other hand, the chemistry of small cycles is an intensively developing branch of organic chemistry. The three-carbon rings are unique fragments that, due to their significant stress, are capable of unusual structural transformations with the expansion and rearrangement of the small ring.
The reactions of the cyclopropane compounds have been actively studied for more than three decades. In the world literature, there are very few examples of works on the functionalization of highly stressed cyclopropane-containing polycyclic hydrocarbons, the reaction products of which can be used widely as precursors for the synthesis of drugs, and as transmission media and working fluids. In addition, the analysis of the literature data showed that the ring-opening reactions of cyclopropanes are catalyzed mainly by transition metal complexes, and that there are no examples of the use of ILs as catalysts or their transformations.

General Procedures and Materials
The 1 H and 13 C NMR spectra were recorded on a Bruker Avance-II 400 Ascend instrument (400 MHz for the 1 H and 100 MHz for the 13 C in CDCl 3 ) and a Bruker Avance-III HD 500 Ascend instrument (500 MHz for the 1 H and 125 MHz for the 13 C in CDCl 3 ).

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The mass spectra were run on a Shimadzu GCMS-QP2010Plus mass spectrometer (SPB-5 capillary column, 30 m by 0.25 mm, helium as the carrier gas, the temperature programming from 40 to 300 • C at 8 • C/min, an evaporation temperature of 280 • C, an ion source temperature of 200 • C, and an ionization energy of 70 eV). The elemental composition of the samples was determined on a Carlo Erba 1106 elemental analyzer. The course of the reaction and the purity of the products were monitored by gas liquid chromatography on a Shimadzu GC-9A, GC-2014 instrument [2 m by 3 mm column, SE-30 silicone (5%) on the Chromaton N-AW-HMDS as the stationary phase, a temperature programming from 50 to 270 • C at 8 • C/min, and helium as the carrier gas (47 mL/min)].

Preparation of Ionic Liquids
The ionic liquids were prepared by the reaction of AlCl 3 , FeCl 3 , ZnCl 2 , or SnCl 2 with Me 3 N-HCl, Et 3 N-HCl, EMIM-Cl, or BMIM-Cl. The Me 3 N-HCl, Et 3 N-HCl, EMIM-Cl, or BMIM-Cl (10 mmol) and a metal (Al (III), Fe (III), Zn (II), Sn (II)) chloride (10-30 mmol) were charged into a glass reactor (V = 50 mL) under argon. The reaction was conducted with continuous stirring at 70-80 • C for 3 h.  5,9 ]tetradecane, and 30 mmol of aliphatic alcohol ROH (where, R = CH 3 , C 2 H 5 , n-C 3 H 7 , n-C 4 H 9 ) were loaded into an ampoule under argon. The reaction was carried out by stirring at 120 • C for 8 h. After the completion of the reaction, the autoclave was cooled to room temperature, the ampoule was opened, and the reaction mixture was filtered through a layer of aluminum oxide (eluent-petroleum ether). The solvent was distilled off on a rotary evaporator. The products were isolated by column chromatography (silica gel from Acros (0.060-0.200 mm), eluent-petroleum ether: ethyl acetate = 10:1).

Results and Discussion
Previously, we found that inorganic ionic liquids actively catalyze reactions from the hep-  [18,19].
Continuing research in this direction, in this work we studied the reaction of another saturated cyclopropane-containing NBD dimer-exo-exo-hexacyclo[9.

Results and Discussion
Previously, we found that inorganic ionic liquids actively catalyze reactions from the  [18,19].
Compounds 1-4 were isolated individually by column chromatography on SiO 2 (eluent-petroleum ether: ethyl acetate = 10:1), the structure of esters 1-4 was proved on the basis of the 1 H and 13 C NMR spectra. Thus, in the 1H NMR spectra of esters 2-4, there are characteristic signals at 3.17-3.66 ppm, belonging to the -O-CH 2 -group protons. In addition, the protons of the -CH-O-group resonate at 3.79-3.88 ppm. Signals at 3.30 ppm and 3.69-3.71 ppm belongs to the -OCH 3 and -CH-O-groups, respectively, of compound 1.
In the 13 C NMR spectra of compounds 1-4, there are characteristic signals of the C 4carbon atom at 82.91-89.98 ppm, as well as signals of the carbon atoms -O-CH 3 (57.72 ppm) and -O-CH 2 -(66.72-74.63 ppm).
Considering the formation of chlorine derivative 6, it can be assumed that esters 1-4 are secondary products, i.e., at the first stage, hydrocarbon 5 reacts with HCl to give chloride 6, which undergoes alcoholysis. To verify this assumption, experiments were carried out with known 4-exo-chloropentacyclo[8.2.1.1 5,8 .0 2,9 .0 3,7 ]tetradecane 6 with alcohols in the presence and absence of IL. The attempts were unsuccessful: the alcohols and the chlorine derivative 6 returned unchanged from the reaction.

Conclusions
Thus, it was found that the ionic liquid [Et 3 NH] + [Al 2 Cl 7 ] − is an effective catalyst for the reaction of exo-exo-hexacyclo[9.