RU2750297C1 - Derivatives of 1-(3-tert-butyl-4-hydroxy-8-methylpyrazolo[5,1-c][1,2,4]triazine-1(4h)-yl)-2,2-difluoroethanones, method for their production and their use as acid photogenerators - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to derivatives of 1-(3-tert-butyl-4-hydroxy-8-methylpyrazolo[5,1-c][1,2,4]triazine-1(4H)-yl)-2,2-difluoroethanones of the general formula (I), which can be used as acid photogenerators in organic solvent solutions and in an optically transparent polymer. In formula (I), R1is hydrogen, and R2is chlorine, or R1is bromine, and R2is chlorine or fluorine. The invention also relates to a method for producing derivatives of 1-(3-tert-butyl-4-hydroxy-8-methylpyrazolo[5,1-c][1,2,4]triazine-1(4H)-yl)-2,2-difluoroethanones of the general formula (I), where R1is hydrogen or bromine, and R2is chlorine or fluorine. The method consists in the fact that a mixture of 7-R1-3-tert-butyl-8-methylpyrazolo[5,1-c][1,2,4]triazine and 2-R2-2,2-difluoroacetic anhydride, where R1and R2have the above values, taken in an equimolar ratio, is treated with water.EFFECT: obtaining acid photogenerators.3 cl, 13 dwg, 3 tbl, 7 ex

Description

The invention relates to derivatives of unsymmetrical triazine, in particular to derivatives of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2-difluoroethanones, their production method and their use as acid photogenerators. In particular, such derivatives can be used individually or in compositions as additives to polymers, in media for optical recording of information, in biological research.

Known inventions of photogenerators of acid (FHA) of various structures, with the possibility of using as initiators of cationic polymerization of various monomers (WO 2020/145043 A1, 07.16.2020), photoresist components in photolithography (US 2020/0133122 A1, 04.30.2020) (US 2019 / 0285983 A1, 19.09.2019) (US 2018/0095363 A1, 05.04.2018), in the processing of semiconductors (US 2020/0096866 A1, 26.03.2020). Thus, the preparation of polymer coatings for micro- and optoelectronic devices with improved characteristics is described, based on compositions containing a mixture of polyimides and FHA (US 2020/0285151 A1, 09/10/2020). Photoresists designed for transferring images on the surface of various materials contain FHA in a polymer matrix containing acid-sensitive fragments. Upon UV irradiation of such compositions, FHA release acids that destroy or crosslink polymer units, which leads to the appearance of an image in the place subjected to UV irradiation (WO 2019/178344 A1, 19.09.2019).

Previously proposed photosensitive polymer materials for optical recording of information, based on photoinduced fluorescence, containing FHA and precursors of fluorescent compounds, such as derivatives of Rhodamine (US 2003/0073031 A1, 17.04.2003). The information is read by detecting the fluorescence of Rhodamine cations. The process of recording information consists in the absorption of UV radiation by FHA, which leads to the release of acid, which in turn leads to the opening of the precursor cycle with the formation of the fluorescent cation Rhodamine. The process proceeds according to the following scheme 1:

Today, the search for new compounds with the properties of FHA remains relevant. Thus, the creation of compounds that can be used in this way is an important task, which is the subject of the present invention.

FHCs described in the literature are divided into two groups - ionic and non-ionic. The advantage of organic nonionic FHA is its increased solubility in organic solvent media and polymer films. The mechanism of acid formation upon irradiation of nonionic FHA consists in hemolytic cleavage of carbon-heteroatom or heteroatom-heteroatom bonds with further free radical abstraction of hydrogen atoms from solvent molecules (N.A. Kuznetsova, G.V. Malkov, B.G. Gribov "Photochemical acid generators . Application and current state of development. "Advances in chemistry, 2020, 89 (2), 173-190).

In (VF Traven, DA Cheptsov, MV Bulanova, NP Solovjova, TA Chibisova, SM Dolotov, IV Ivanov. "On the Mechanism of Photodehydrogenation of Aryl (hetaryl) pyrazolines in the Presence of Perchloroalkanes." Photochem. Photobiol. 2018, 94 , 659) describe nonionic two-component FHA, consisting of a mixture of dihydrohetarene, in particular pyrazoline derivatives, with a perhaloalkane such as carbon tetrachloride or hexachloroethane. When the composition is irradiated, photodehydrogenation occurs, accompanied by aromatization of dihydrohetarene and the release of hydrogen chloride acid according to the following scheme 2:

Where R is hydrogen or a hydroxyl group, A is CCl ₄ or C ₂ Cl ₆ .

Such two-component systems are promising both for optical recording of information and for biological research; they are distinguished by high rates of acid generation. Among the disadvantages of FHAs of this class are the pronounced dependence of the rate of acid generation on the solvent used, the need for careful control of the ratio of the introduced reagents, the high volatility of the evolved gaseous hydrogen chloride, and the high toxicity of polychloroalkanes for humans.

Recently, ionic FHAs have been proposed, based on modified sulfonic acid anions containing CF ₂ , CH ₂ , O groups, as well as their analogs (US 2020/0133122 A1, April 30, 2020) having the formulas:

Where Z is a mono- or polycyclic group with a lactam structure; Rf ¹ -Rf ⁴ are hydrogen, fluoro or trifluoromethyl; R ¹ , R ² is hydrogen or a C ₁ -C ₂₀ monovalent hydrocarbon group which may contain a heteroatom; L ¹ -L ³ - single, ether, ester bond, including sulfonic acid ester, carbonate or carbamate; X ¹ is a single bond or a C ₁ -C ₄₀ divalent hydrocarbon substituent that may contain a heteroatom; n ¹ = an integer from 0 to 6, taking into account that R ¹ and R ² can form a cyclic structure; Q is an onium cation. Examples:

The patent (EP 0 938 029 A2, 25.08.1999) describes nonionic FHA of a similar structure, namely, based on amides of perfluorinated sulfonic acids, capable of generating free acids upon irradiation. In the patent (WO 2006/008250 A2, 26.01.2006) halogenated O-sulfonates of oximes, capable of acting as nonionic FHA, of the formula:

Where R ¹ is C ₁ -C ₁₈ -alkyl or arylsulfonyl; R ¹ is halogen or C ₁ -C ₁₀ -haloalkyl; X is halogen; Ar ¹ - biphenyl, fluorenyl, substituted naphthyl, or substituted hetaryl.

As a development of this work, modern patents (WO 2016/148809 A1, 09.22.2016) (US 2020/0089110 A1, 03.19.2020) describe nonionic FHAs, which are derivatives of O-sulfonated 2-hydroxy-1H-benzo [de] isoquinoline -1,3 (2H) -diones of the formulas:

Where R ¹ and R ² are hydrogen, cyano group, aliphatic or heterocyclic substituents C ₁ -C ₁₈ , which in addition may contain halogen atoms, carbonyl, amine, ether, sulfide groups; R ³ is a fluorinated alkyl group.

Known patent (US 2018/0046077 A1, 15.02.2018), which shows methods of obtaining non-ionic FHA containing fragments of aryl ketones and esters of sulfonic acids, functionalized with groups CF ₂ , CF ₃ , as well as bulky adamantyl formulas:

Where n = 1,2,3,4; Ar is an aryl radical containing one or more aromatic rings; L '- a single bond or a bivalent linker of the composition C ₁ -C ₁₀ ; R ¹ is a monovalent alkyl or perforated alkyl radical of the composition C ₁ -C ₁₀ ; R ² is a radical with valence n of the composition C ₁ -C ₅₀ . Examples:

These compounds are effective as FHA in the UV light range with wavelengths of 0-300 nm and are proposed for use in lithography, as components in polymer matrices of photoresists of various structures. The FHAs described in the patent are effective both in solutions of various organic solvents (such as acetone, ethylene glycol, ethyl acetate, etc.) and in polymer media (polymers, oligomers, molecular glasses, organometallic complexes, etc.). A definite advantage of these photogenerators is the high strength of the formed acids, thermal stability up to 130-140 ° C. A well-known patent can be considered as the closest solution to the technical problem of the invention according to the properties of known compounds and their use as photogenerators.

Among the significant disadvantages of the known FHAs containing a sulfonyl fragment, including those discussed above, are low solubility along with high chemical resistance, which prevents biodegradability, and a tendency to accumulate sulfonic acids in biological objects. (NA Kuznetsova, GV Malkov, BG Gribov "Photochemical acid generators. Application and current state of development." Advances in Chemistry, 2020, 89 (2), 173-190). In the synthesis of FHAs described in the patent (US 2018/0046077 A1, 15.02.2018), fluoroanhydrides of sulfonic and carboxylic acids are used as precursors, which release highly toxic hydrogen fluoride.

The closest in structure to the proposed compounds and the method of production is 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2,2-trifluoroethanone (2а), which is described in the article (S. M. Ivanov, K. A. Lysenko, V. F. Traven, “Synthesis and photolysis of 3-tert-butyl-4-hydroxy (mercapto ) -1,4-dihydropyrazolo [5,1-c] [1,2,4] triazines ", Izv. AN Ser. Chem. 2020, V. 69, No. 4, pp. 731-738). The compound was obtained by reacting 3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2,4] triazine with trifluoroacetic anhydride in THF, followed by the action of aqueous potassium carbonate at reduced temperature. This compound has been tested for antimicrobial and antifungal activity.

The technical objective of the present invention is to expand the range of a new type of FGC, providing the formation of stable photoproducts, and the development of a method for their production.

The stated technical problem is achieved by derivatives of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2-difluoroethanones general formula:

where R ¹ is hydrogen and R ² is chlorine, or R ¹ is bromine and R ² is chlorine or fluorine. The proposed compounds are new and have not been described in the literature. A method for the preparation of derivatives of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2-difluoroethanones is also proposed. general formula:

where R ¹ represents hydrogen or bromine, and R ² represents chlorine or fluorine, which consists in the fact that a mixture of 7-R ¹ -3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2, 4] triazine and 2-R ² -2,2-difluoroacetic anhydride, where R ¹ and R ² have the above meanings, taken in an equimolar ratio, are treated with water.

The process is carried out at room temperature for 5 minutes in the absence of an organic solvent according to the following scheme 3:

The proposed method differs from the known one by using water instead of potassium carbonate as a reagent, by the precise selection of the ratio of reagents, by the absence of an organic solvent and by carrying out the process at room temperature, which is more environmentally friendly and easier in technical implementation.

Compounds of general formula I, where R ¹ is hydrogen or bromine, and R ² is chlorine or fluorine, can be used as photosensitive photogenerators of stable photoproducts, such as trifluoroacetic acid (TPA) or chlorodifluoroacetic acid (CDFA), and are effective in solutions of an organic solvent and in media of an optically transparent polymer. Since the previously known compound 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2,2- trifluoroethanone (2а) was tested in an aqueous solution, which could lead to its hydrolysis; it was not obvious that compound 2а could act as FHA in an inert anhydrous medium.

Compounds 2a-d possess the properties of FHA, which, when exposed to UV radiation in the 235-492 nm range, form TPA or HDPA in solutions of organic solvents, for example, acetonitrile, and in an optically transparent polymer, for example, polymethyl methacrylate (PMMA).

The obtained new type of FHA under UV irradiation provides the formation of stable photoproducts that do not produce volatile hydrohalic acids or toxic halogenated sulfonic acids. TPA and HDPA are strong acids that are readily soluble both in water and in environments of various organic solvents and polymers, and are characterized by moderate boiling points. TPA and the corresponding trifluoroacetates (TFA) are not prone to bioaccumulation, in contrast to fluorinated sulfonic acids. For example, the results of analysis of samples of ocean water show that TFA found everywhere at a concentration of about 200 ng / L is of natural origin and is homogeneously distributed in ocean water of all ages (Hartmut Frank, Eugen H Christoph, Osmund Holm-Hansen, John L Bullister. "Trifluoroacetate in Ocean Waters" Environ Sci Technol. 2002, 36 (1), 12-5. Doi: 10.1021 / es0101532).

The invention is illustrated by the following non-limiting examples.

Example 1.

Synthesis of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2,2-trifluoroethanone (2а ).

To 3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2,4] triazine (1а) (10 mmol), 2,2,2-trifluoroacetic anhydride (10.5 mmol) is added over 1 min. The mixture thus obtained is left stirring for 5 minutes and then poured into 100 ml of water. The process is carried out at room temperature. The white crystalline solid is filtered, washed with water (1 × 100 ml) and air-dried in the dark. 2.95 g (97%) of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2.2 , 2-trifluoroethanone (2а) with m.p. 181-183 ° C (decomp.). M.p. and spectral data for compound 1а correspond to those previously described (S. M. Ivanov, K. A. Lysenko, V. F. Traven, “Synthesis and photolysis of 3-tert-butyl-4-hydroxy (mercapto) -1,4-dihydropyrazolo [5,1-c] [1,2,4] triazines ", Izv. AN Ser. Chem. 2020, T. 69, No. 4, S. 731-738). The molecular structure of FHA 2a in a crystal in the representation of atoms as thermal vibration ellipsoids (p = 50%) is shown in Fig. one.

Example 2.

Synthesis of 1- (7-bromo-3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2,2 -trifluoroethanone (2b).

To 7-bromo-3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2,4] triazine (1b) (10 mmol), 2,2,2-trifluoroacetic anhydride ( 10.5 mmol). The mixture thus obtained is left stirring for 5 minutes and then poured into 100 ml of water. The process is carried out at room temperature. The white crystalline solid is filtered, washed with water (1 × 100 ml) and air-dried in the dark. 3.69 g (96%) of 1- (7-bromo-3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) are obtained -2,2,2-trifluoroethanone (2b) m.p. 173-176 ° C (decomp.). IR spectrum (KBr), ν / cm ^-1 : 3168 (OH), 2994, 2964, 2941, 2909, 2873, 2726 (CH), 1745 (CO), 1691, 1650, 1642, 1564, 1513, 1482, 1454, 1413, 1388, 1368, 1338, 1301, 1281, 1252, 1225, 1203, 1172 (CF ₃ ), 1103, 1083, 1060, 1028, 1012, 920, 857, 792, 743, 717, 667, 632, 584, 555, 533, 517, 456. ¹ H NMR (500 MHz, DMSO-d ₆₎ δ / ppm. (J / Hz) = 1.29 (s, 9H, t-Bu), 2.08 (s, 3H, C (8) -Me), 6.33 (s, 1H, C (4) -H), 7.82 (d ~ 0.5 H, OH, J = 8.5). ¹³ C NMR APT (126 MHz, Dimethyl sulfoxide-d ₆ ) δ / ppm. (J / Hz) = 11.44 (C (8) - C H _3), 28.24 (C (C H _{3) 3),} 37.84 (C _{(CH3) 3),} 70.56, 70.66 (d, C (4) J = 12.0), 105.13 (C (8)), 112.90, 115.17, 117.46, 119.74 (q, CO C F ₃ , J = 286.8), 130.18 (C (7)), 130.57 (C (8a)), 151.87 , 152.17, 152.47, 152.76 (q, C OCF ₃ , J = 37.5), 162.41, 162.50 (d, C (3), J = 11.6). ¹⁹ F NMR (471 MHz, Dimethyl sulfoxide-d ₆ ) δ / ppm. = -68.65 (s, 3F, CF ₃ ). HRMS (ESI): m / z: [M + H] calculated for C ₁₂ H ₁₄ BrF ₃ N ₄ O ₂ : 383.0325; found 383.0325.

Example 3.

Synthesis of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2-chloro-2,2-difluoroethanone (2c).

To 3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2,4] triazine (1а) (10 mol), 2-chloro-2,2-difluoroacetic anhydride (10.5 mmol ). The mixture thus obtained is left stirring for 5 minutes and then poured into 100 ml of water. The process is carried out at room temperature. The white crystalline solid is filtered, washed with water (1 × 100 ml) and air-dried in the dark. 3.09 g (96%) of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2-chloro -2,2-difluoroethanone (2с) with m.p. 199-202 ° C (decomp.). IR spectrum (KBr), ν / cm ^-1 : 3104 (OH), 2974, 2932, 2907, 2871, 2836, 2707 (CH), 1734 (CO), 1652, 1631, 1586, 1560, 1517, 1479, 1466, 1451, 1411, 1384, 1360, 1306, 1252, 1218, 1170 (CF ₂ ), 1147, 1105, 1095, 1060, 1040, 1015, 1002, 964, 916, 872, 849, 816, 792, 767, 699, 670, 652, 632, 612, 542, 464, 451, 431. ¹ H NMR (500 MHz, Dimethyl sulfoxide-d ₆ ) δ / ppm. = 1.29 (s, 9H, t-Bu), 2.09 (s, 3H, C (8) -Me), 3.60-3.70 (br s, ~ 1H, OH), 6.32 (s, 1H, C (4) -H), 7.53 (s, 1H, C (7) -H). ¹³ C NMR APT (126 MHz, Dimethyl sulfoxide-d ₆ ) δ / ppm. (J / Hz) = 11.02 (C (8) - C H _3), 28.35 (C (C H _{3) 3),} 37.80 (C _{(CH3) 3),} 70.69 (C (4)), 105.03 (C (8)), 116.03, 118.41, 120.78 (t, CO C F ₃ , J = 299.2), 129.37 (C (8а)), 141.94 (C (7)), 153.54, 153.79, 154.04 (t, C OCF ₃ , J = 30.9), 161.84 (C (3)). ¹⁹ F NMR (471 MHz, Dimethyl sulfoxide-d ₆ ) δ / ppm. = -59.71, -59.38, -57.29, -56.95 (diastereotopic m., Σ 2F, CF ₂ ). HRMS (ESI): m / z: [M + H] calculated for C ₁₂ H ₁₅ ClF ₂ N ₄ O ₂ : 321.0924; found 321.0932.

Example 4.

Synthesis of 1- (7-bromo-3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2-chloro-2 , 2-difluoroethanone (2d). To 7-bromo-3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2,4] triazine (1b) (10 mmol), 2-chloro-2,2-difluoroacetic anhydride (10.5 mmol). The mixture thus obtained is left stirring for 5 minutes and then poured into 100 ml of water. The process is carried out at room temperature. The white crystalline solid is filtered, washed with water (1 × 100 ml) and air-dried in the dark. 3.85 g (96%) of 1- (7-bromo-3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) are obtained -2-chloro-2,2-difluoroethanone (2d) m.p. 183-184 ° C. IR spectrum (KBr), ν / cm ^-1 : 3184 (OH), 2966, 2939, 2909, 2872, 2723 (CH), 1740 (CO), 1632, 1572, 1521, 1453, 1377, 1333, 1288, 1239, 1211, 1146, 1090 (CF _2), 1029, 965, 908, 853, 825, 787, 705, 667, 622, 560, 466. ¹ H NMR (300 MHz, CDCl ₃₎ δ / ppm. = 1.41 (s, 9H, t-Bu), 2.20 (s, 3H, C (8) -Me), 6.36 (s, 1H, C (4) -H), 7.20-7.60 (br s, ~ 1H , IS HE). ¹³ C NMR APT (75 MHz, CDCl ₃ ) δ / ppm. (J / Hz) = 11.66 (C (8) - C H _3), 28.49 (C (C H _{3) 3),} 38.19 (C _{(CH3) 3),} 70.24 (C (4)), 106.76 (C (8)), 113.91, 117.89, 121.88 (t, CO C F ₃ , J = 301.0), 131.27, 131.99 (C (8а), C (7)), 154.29, 154.72, 155.14 (t, C OCF ₃ , J = 31.8), 159.61 (C (3)). ¹⁹ F NMR (282 MHz, CDCl ₃ ) δ / ppm. = -61.25, -60.69, -58.85, -58.29 (diastereotopic m., Σ 2F, CF ₂ ). HRMS (ESI): m / z: [M + H] calculated for C ₁₂ H ₁₅ ClF ₂ N ₄ O ₂ : 399.0030; found 399.0026.

Example 5.

UV irradiation of solutions of compounds 2a-d in an organic solvent.

Compound 2a-d (1.5⋅10 ^-3 mmol) was dissolved in 5 ml of acetonitrile. Lactone Rhodamine B (1 mg, 2.26⋅10 ^-3 mmol) was dissolved in 10 ml of acetonitrile. 0.4 ml of concentrated solution 2a-d and 1.6 ml of acetonitrile were placed in a cuvette. The concentration of 2a-d in the test solution was C = 6⋅10 ^-5 M.

Compounds 2a-d in the form of solutions in acetonitrile have two absorption maxima in UV spectra, namely at 238-256 nm and about 275-290 nm. In fig. 2 shows the changes in UV absorption spectra upon UV irradiation of a FHA 2b solution in acetonitrile through an A03 light filter, the maximum irradiation time is 240 s. In fig. 3 shows the changes in the absorption spectra upon irradiation of compound 2c in acetonitrile through an A03 light filter, the maximum irradiation time is 300 s.

As a result of irradiation of solutions of compounds 2a-d with UV light in the wavelength ranges of 235-492 nm, a gradual decrease in the intensity of the long-wavelength maximum is observed, and a slight increase in optical density in the range from 310 to 400 nm without the formation of a clearly pronounced absorption maximum. The changes in the relative intensity of the long-wavelength maximum during the irradiation time of 240 s for compounds 2a-d with the same external parameters of the experiments are presented in Table 1.

After the completion of irradiation 2a-d, 200 μL of a solution of lactone Rhodamine B was added to the resulting solution.As a result, the formation of intense absorption with a maximum at about 556 nm, corresponding to the open form of Rhodamine B, is observed, which indicates the presence of acid in the system. In fig. 4 shows the UV absorption spectra of a solution of irradiated FHA 2a before and after the addition of a solution of lactone Rhodamine B in acetonitrile. Additionally, the absorption spectrum of a diluted solution of lactone Rhodamine B in acetonitrile was recorded. After recording the spectrum, 400 μl of an unirradiated concentrated solution of compound 2a-d was added. In fig. 5 shows the UV absorption spectra of a solution of lactone Rhodamine B before and after the addition of an unirradiated solution of FHA 2a in acetonitrile to it. Changes in the spectrum of the resulting mixture are insignificant, which confirms the formation of acid upon irradiation of compounds 2a-d.

Example 6.

UV irradiation of solutions of a mixture of compounds 2a-d and rhodamine B lactone in an organic solvent.

Compound 2a-d (1.5⋅10 ^-3 mmol) was dissolved in 5 ml of acetonitrile. Lactone Rhodamine B (1 mg, 2.26⋅10 ^-3 mmol) was dissolved in 10 ml of acetonitrile. 0.4 ml of concentrated solution 2a-d, 0.4 ml of lactone Rhodamine B solution, and 1.2 ml of acetonitrile were placed in a cuvette. The concentration of 2a-d in the test solution was C = 6⋅10 ^-5 M. The concentration of Rhodamine B lactone in the test solution was C = 4.52⋅10 ^-5 M. Under UV irradiation of solutions of a mixture of compounds 2a-d and lactone Rhodamine B in acetonitrile UV light in the 235-492 nm wavelength range shows a decrease in the intensities of the absorption band maxima of the starting substances with the formation of an intense signal of the Rhodamine B cation at 558 nm; in the case of UV spectrum 2c, the formation of clear isobestic points is recorded. In fig. 6 shows changes in UV absorption spectra upon irradiation of a solution of a mixture of FHA 2c with lactone Rhodamine B in acetonitrile through an A03 light filter, the maximum irradiation time is 240 s. The increase in the relative intensity of the absorption band of the Rhodamine B cation during the irradiation time of 30-240 s for a mixture of the lactone Rhodamine B and compounds 2a-d with the same external parameters of the experiments is presented in Table 2.

Irradiation of a solution of lactone Rhodamine B in acetonitrile without adding any compounds leads to the opening of the lactone ring with the formation of the fluorescent form of the dye, but the relative intensity of its absorption band in the UV spectrum is negligible. In fig. 7 shows the changes in the UV absorption spectra of a solution of lactone Rhodamine B in acetonitrile without any additives under UV irradiation through an A03 light filter, the maximum irradiation time is 240 s.

Example 7.

UV irradiation of compounds 2a-d in a polymer film of polymethyl methacrylate (PMMA).

Lactone Rhodamine B (0.5 mg, 1.13⋅10 ^-3 mmol), compound 2a-d (6⋅10 ^-3 mmol) and PMMA (250 mg) are dissolved in a mixture of 3.6 ml of ethyl acetate and 0.4 ml of toluene. The solution is filtered through a glass Schott filter (pore 3) into a horizontally placed Petri dish. Dry at a temperature of 35-50 ° C for 24 hours, then 15 minutes at 75 ° C.

As a result of UV irradiation of polymer films containing lactone Rhodamine B and compound 2a-d with UV light in the wavelength ranges of 235-492 nm or 310-460 nm, a gradual increase in the absorption maximum in the 560 nm region is observed, corresponding to the characteristic absorption band of the open form of the dye, namely, the cation of Rhodamine B (see Scheme 1). So, in fig. Figures 8 and 9 show changes in UV absorption spectra of a mixture of FHA 2c with lactone Rhodamine B in a polymer PMMA film under UV irradiation through A03 or A05 light filters, respectively (maximum exposure time 30 s). In fig. Figures 10 and 11 show changes in the UV absorption spectra of a mixture of FHA 2a or 2d, respectively, with the lactone Rhodamine B in a polymer PMMA film under UV irradiation through an A03 light filter (maximum irradiation time 30 s). The increase in the relative intensity of the absorption band of the Rhodamine B cation for compounds 2a-d with the same external parameters of the experiments is presented in Table 3.

Irradiation of the PMMA film with Rhodamine B lactone without the addition of compounds 2a-d leads only to a slight increase in the background absorption in the region of 340 to 750 nm. In fig. 12 and 13 show changes in the UV absorption spectra of lactone Rhodamine B in a polymer PMMA film without any additives under UV irradiation through A03 or A05 light filters, respectively (the maximum irradiation time is 40 s or 180 s, respectively).

Analysis of the results obtained shows that compounds 2a-d under the action of UV radiation with wavelengths of 235-492 nm undergo photochemical transformations with the formation of an acid, which is fixed by reaction with the lactone of Rhodamine B and after irradiation does not return to its original form. Therefore, the resulting compounds 2a-d are photosensitive, provide irreversible acid formation, and are effective FHAs. Compounds 2a-d are effective as FHAs in organic solvent solutions and in polymer films.

) в Отделе Структурных Исследований Института Органической Химии им. Н.Д. Зелинского РАН, Москва.The starting compounds 7-R ¹ -3-tert-Butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazines (R ¹ = H, Br) were synthesized according to the methods described in the works (SM Ivanov, AM Shestopalov. Interaction of Fused 1,2,4-Triazinone with Diborane / Oxidation: A New Route for the Synthesis of Partially Saturated and Aromatic Pyrazolo [5,1-c] [1,2,4] triazines " J. Heterocycl. Chem. 2018, Volume 55, Issue 10, Pages 2427-2433) and (SM Ivanov, AO Dmitrienko, MG Medvedev, LM Mironovich. “Metalated azolo [1,2,4] triazines. II. Generation, C (4) -substituent dependent stability and electrophile trapping of 7-lithiopyrazolo [5,1-c] [1,2,4] triazines. "J. Organomet. Chem. 2019, 896, 168-182). 2-R ² -2,2-Difluoroacetic anhydrides (R ² = F, Cl), acetonitrile ("reference") and polymethyl methacrylate (PMMA) are used as they were obtained from commercial sources ("Sigma-Aldrich" ). Temperatures are indicated in degrees Celsius (° C). All operations are carried out at room temperature (20 ° C). ¹ H, ¹³ C (APT, bound proton test) and ¹⁹ F NMR spectra were recorded on Bruker AM-300 or Bruker DRX-500 instruments, operating frequencies, respectively, 300, 500 MHz ( ¹ H), 75, 126 MHz ( ¹³ C), 282, 471 MHz ( ¹⁹ F). Internal standard - DMSO-d ₅ , CHCl ₃ ( ¹ H), DMSO-d ₆ CDCl ₃ ( ¹³ C), CF ₃ CO ₂ H ( ¹⁹ F). IR spectra were recorded on an Agilent Cary 660 FTIR FTIR spectrometer in KBr pellets. High resolution mass spectra (HRMS) were recorded on a Bruker micrOTOF II instrument by electrospray ionization (ESI). The measurements were carried out on positive (capillary voltage - 4500 V) ions, the solvent is acetonitrile. Melting points were determined on a STUART Melting point SMP30 apparatus. X-ray structural analysis was carried out at 100 K on a Bruker Quest D8 diffractometer (λ (MoKa) = 0.71073

) in the Department of Structural Research of the Institute of Organic Chemistry. N. D. Zelinsky RAS, Moscow.

UV spectra were recorded on an SF-104 spectrophotometer. Photolysis was carried out in an air atmosphere in a quartz flask under irradiation with a Hamamatsu LC-4 UV source with an L8253 xenon lamp (power 150 W) through A03 light filters (transmission range 235-492 nm) or A05 (transmission range 310-460 nm) ... Irradiation was carried out with constant stirring (for solutions) and cooling with an external fan to maintain room temperature (20 ° C). EFFECT: new photosensitive acid photogenerators have been obtained, which can be used in organic solvent solutions and in optically transparent polymer, and a simplified method for their production at room temperature without using an organic solvent is proposed, which is more environmentally friendly and easier in technical implementation. The resulting new type of FHA provides, when exposed to UV radiation in the 235-492 nm range, the formation of stable photoproducts that do not produce volatile hydrohalic acids or toxic halogenated sulfonic acids.

Claims (7)

1. Derivatives of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2-difluoroethanones of the general formula

where R ¹ is hydrogen and R ² is chlorine, or R ¹ is bromine and R ² is chlorine or fluorine. 2. A method of obtaining derivatives of 1- (3-tert-butyl-4-hydroxy-8-methylpyrazolo [5,1-c] [1,2,4] triazin-1 (4H) -yl) -2,2-difluoroethanones general formula

where R ¹ represents hydrogen or bromine, and R ² represents chlorine or fluorine, which consists in the fact that a mixture of 7-R ¹ -3-tert-butyl-8-methylpyrazolo [5,1-c] [1,2, 4] triazine and 2-R ² -2,2-difluoroacetic anhydride, where R ¹ and R ² have the above meanings, taken in an equimolar ratio, are treated with water. 3. The use of compounds of general formula (I) according to claim 1 as photogenerators of an acid in solutions of an organic solvent and in an optically transparent polymer.

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