Photochromic and thermochromic spiranes. 34.* synthesis of photochromic 5-(4,5-diphenyl-1,3-oxazol-2-yl)-substituted spirobenzochromeneindolines

A simple and effective method is proposed for the synthesis of 4,5-diphenyloxazolyl-substituted o-hydroxynaphthaldehydes. Photochromic spirobenzochromeneindolines containing a 4,5-diphenyl-oxazole group at position 5 of the benzochromene fragment were obtained. In the cyclic form the new (diphenyloxazolyl)-substituted spiropyrans exhibit luminescent properties.

Introduction

The synthesis and investigation of new effective photochromic systems with the aim of creating poly-functional materials for molecular electronics and chemical sensors is a currently important problem [2,3]. A special place among known types of photochromic compounds is occupied by relatively easily synthesized spiropyrans, the spectral and kinetic characteristics of which vary over a large range depending on the molecular structure [2–4].

The mechanism of the photochromic transformations of spiropyrans (Scheme 1) involves the thermally and photochemically reversible heterolytic cleavage of the C_spiro–O bond of the cyclic isomer 1A followed by cis–trans isomerization to the metastable merocyanine form 1B [2–4].

 

The insertion of various functional fragments into the spiropyran molecule opens up the possibility of obtaining a wide range of polyfunctional photochromic molecular systems exhibiting magnetic [5], fluorescent [6–9], and complexing [9–12] properties switched on by optical radiation. Earlier we reported on the synthesis of photochromic 5-(4,5-diphenyl-1,3-oxazol-2-yl)-substituted spiropyrans, the acyclic isomer of which forms reversibly complexes with the divalent cations of heavy metals [13]. The present work is a continuation of these investigations and is devoted to the synthesis of new spiropyrans containing a diphenyloxazolyl group at position 5 of the benzochromene fragment and their spectral and photochromic characteristics.

A convenient method for the production of 2,4,5-triaryl-1,3-oxazoles is cyclization of the esters of ben-zoin and aromatic acids (desyl esters), which can be obtained by the acylation of benzoin by Davidson's method [14]. In the case of 2-(hydroxyaryl)-4,5-diphenyl-1,3-oxazoles, the method of production of the desyl esters by the alkylation of the salts of the corresponding carboxylic acids with desyl chloride under the conditions of phase-transfer catalysis is preferred [15,16].

5-(Diphenyloxazolyl)-substituted spiropyrans 1a–h were obtained in two stages by the reaction of 3H-indolium salts 2a–d with diphenyloxazolyl-substituted hydroxynaphthaldehydes 3a,b in acetic acid with isolation of the obtained salts of o-hydroxynaphthylvinyl derivatives 4a–h and treatment of the latter with ammonia (method A). The spiropyrans 1i–o were obtained in one stage by the condensation of the 3H-indolium salts 2e–h with hydroxynaphthaldehydes 3a,b in the presence of triethylamine as base (method B) (Scheme 2). The diphenyloxazolyl-substituted aldehydes 3a,b were obtained by the formylation of diphenyloxazolyl-substituted naphthols 5a,b.

Scheme 2

 

Instead of the previously described multistage method for the synthesis of the diphenyloxazolyl-substituted aldehyde 3a [17] it is possible to propose a simple and effective method for the synthesis of the aldehydes 3a,b (Scheme 3).

Scheme 3

 

The starting compounds for the synthesis of the aldehydes 3a,b were the sodium salts of the acids 6a,b, the alkylation of which with 2-chloro-1,2-diphenylethanone (desyl chloride, 7) under the conditions of phase-transfer catalysis in a solid phase–liquid system in the presence of 15-crown-5 gave the desyl esters 8a,b. Reaction of the desyl esters 8a,b with ammonium acetate in acetic acid by Davidson’s method [14] gave the diphenyloxazolyl-substituted naphthols 5a,b, the formylation of which by the Duff method in acetic acid gave the o-hydroxynaphthaldehydes 3a,b.

The colorless or weakly colored 5-diphenyloxazolyl-substituted spiropyrans 1a–o were purified by chromatography and recrystallized. The structure of compounds 1a–o, 3a,b, 5a,b, and 8a,b was established by ¹H NMR spectroscopy and confirmed by elemental analysis.

By ¹H NMR spectroscopy it is possible to establish quickly and accurately the structure of spiropyrans of the indoline series from the characteristic shifts, spin–spin coupling constants, and the number of different types of protons. The signals of such characteristic (indicator) groups as a gem-dimethyl group, an N-alkyl substituent, and the protons of the C(3) = C(4) double bond are usually determined easily and have different chemical shifts for the open and closed forms [18–20].

The upfield region of the spectrum of the spiropyrans contains two easily identified signals from the magnetically nonequivalent geminal methyl groups, the signal of the N-alkyl substituent (Me, Pr, All, i-Bu), and signals of the corresponding indicator groups of the substituents (Me, OMe, OAll) in the spiropyran.

The prochirality of the methylene group of the N-allyl substituent (spiropyrans 1i,j,m,n) and the methyl groups and the protons of the methylene group of the N-isobutyl substituent (spiropyrans 1 l,o) leads to diastereotopic splitting of the signals of these groups, which appear in the form of two double doublets at 3.00 and 3.06 and two doublets at 0.87 and 0.91 ppm respectively.

The downfield part of the spectrum of the spiropyrans 1a–o contains several groups of interdependent signals of protons belonging to the indoline and pyran fragments of the molecule and the signals of two groups, each of five interacting nuclei, belonging to the phenyls of the diphenyloxazolyl substituent. Unlike the diphenyloxazolyl-substituted naphthols 5 and aldehydes 3, in the ¹H NMR spectra of which the signals of the ten protons of the phenyl groups appear in the form of four-proton and six-proton multiplets, in the ¹H NMR spectra of the spiropyrans 1 the signals of the protons of the two phenyl rings in the oxazole group form a complex picture of four multiplets with integral intensities of 2:3:3:2.

Thus, the structure of the obtained spiropyrans is confirmed unambiguously by the data from ¹H NMR spectroscopy (two signals from the magnetically nonequivalent geminal methyl groups, signals from the protons of the phenyl rings of the diphenyloxazolyl group, diastereotopic splitting of the signals for the protons of the N-alkyl substituent, the values of the chemical shifts of the protons and the spin–spin coupling constants of the diastereotopic protons of the N-isobutyl and N-allyl substituents, the protons of the double bond in the pyran fragment, and the protons of the indoline and pyran fragments). The absence of signals for the N-methyl and gem-dimethyl groups, the trans-vinyl protons, and other protons of the indoline and benzochromene fragments in the regions of the spectra characteristic of the open merocyanine form indicates that the obtained compounds exist in solution in CDCl₃ mainly in the spirocyclic form.

The electronic absorption spectra of the cyclic forms 1A of the spiropyrans 1a–o in toluene solution are characterized by the presence of several bands. The less intense long-wave band with a molar extinction coefficient at the maximum of 4.5–9.0 × 10³ l·mol⁻¹·cm⁻¹ is characterized by two poorly resolved maxima in the region of 380–395 nm (compounds 1a–c,i–l, Table 1). The introduction of a methoxyl substituent at position 8 of the benzochromene fragment of the molecule gives rise to a bathochromic shift of this band by 10–15 nm (compounds 1e–h,m–o). The position of the maxima of the more intense short-wave absorption bands of compounds 1a–o (ε = 36.4–20.4 × 10³ l·mol⁻¹·cm⁻¹) does not depend on the nature of the substituents and is located in the region of 310 and 340 nm.

Table 1 The Spectral Characteristics of Compounds 1a-o*

It was established that the cyclic forms of the spiropyrans at 293 K have fluorescent characteristics. The fluorescence emission spectrum represents a broad band in the region of 400–600 nm with poorly resolved maxima at 410 and 430 nm. As also in the case of the absorption spectra, the introduction of a methoxyl substituent at position 8 of the benzochromene part of the molecule leads to a bathochromic shift of the maxima of the fluorescence band by 20–25 nm.

At 77 K the solutions of compounds 1a–o exhibit strong fluorescence, which is characterized by a struc-tured band with maxima at 580, 630, and 690 nm; their position hardly depends at all on the nature of the substituents in the indoline and pyran parts of the molecule. The fluorescence and phosphorescence excitation spectra practically coincide with each other, and the position of their maxima correlates well with the position of the maxima in the absorption spectrum, providing grounds for attributing the observed luminescent characteris-tics to the spirocyclic isomers of the synthesized compounds (Fig. 1, Table 1).

Fig. 1

The absorption spectrum (1) of a solution of 1 g and the fluorescence emission (2) and excitation (3) spectra of the spirocyclic isomer 1 g, T = 293 K, solvent toluene. The phosphorescence emission (4) and excitation (5) spectra of the spirocyclic isomer 1 g, T = 77 K, solvent toluene–ethanol–diethyl ether.

Compounds 1a–o exhibit photochromic properties at temperatures below room temperature, and this is due to the high rates of thermal recyclization of the isomers 1B → 1A. Thus, during the exposure of acetone solutions of these compounds in the region of the long-wave absorption of the cyclic forms 1A at T 270 K their colorization, accompanied by the appearance of bands in the electronic absorption spectra in the region of 550–650 nm (Fig. 2, Table 1) characteristic of the noncyclic merocyanine isomers 1B of the spiropyrans, is observed [2–4]. The position of the maximum of the long-wave absorption band of the merocyanine form 1B in the series of compounds 1a–o is shifted appreciably into the long-wave region of the spectrum with the introduction of the methoxy group at position 5 of the benzochromene part of the spiropyran.

Fig. 2

The variation of the absorption spectra of a solution of 1 g in acetone during irradiation with light at 365 nm, spectrum recording interval 5 s.

Thus, the obtained new 5-(4,5-diphenyl-1,3-oxazol-2-yl)-substituted spirobenzochromeneindolines pos-sess fluorescence and phosphorescence in the spirocyclic form and exhibit photochromic properties in solutions.

Experimental

The ¹H NMR spectra were recorded on a Varian Unity-300 spectrometer (300 MHz) in CDCl₃. The sig-nals were assigned with reference to the signal of the residual protons of the deuterated solvent (δ 7.26 ppm). The electronic absorption spectra of the investigated compounds were recorded on an Agilent 8453 spectropho-tometer with a thermostat attachment for the samples, and the electronic spectra were recorded on a Varian Cary Eclipse spectrofluorimeter. Photolysis of the solutions was realized with a DRSh-250 lamp with a set of interference filters. Toluene and acetone (Aldrich) of spectral purity were used to prepare the solutions. The sodium salt of the acid 6b was the commercial product (Fluka).

The sodium salt of the acid 6a, the desyl chloride 7, and the 3H-indolium salts 2a-d were obtained by the previously described methods [16,21–25].

2-Oxo-1,2-diphenyl Esters of 3-Hydroxy-2-naphthoic Acids 8a,b (General Method). A mixture of the sodium salt 6a,b (33 mol), 15-crown-5 (1 ml, 5 mmol), and acetonitrile (90 ml) was stirred at 70 °C for 30 min, and desyl chloride 7 (6.93 g, 30 mmol) was added. The mixture was stirred with boiling for 7 h and poured into 200 ml of water and ice. The precipitate was filtered off, washed with water, and dried. The obtained esters were recrystallized from a mixture of 2-propanol and toluene.

2-Oxo-1,2-diphenylethyl Ester of 3-Hydroxy-2-naphthoic Acid (8a). Yield 81%; mp 152–153.5 °C (2-propanol–toluene, 3:1). ¹H NMR spectrum, δ, ppm (J, Hz): 7.17 (1H, s, 2-COOCH); 7.29–7.34 (2H, m, H-4,7); 7.42–7.64 (9H, m, H-6, H Ph); 7.68 (1H, d, J = 8.4, H-5); 7.82 (1H, d, J = 8.4, H-8); 8.00–8.03 (2H, m, H Ph); 8.64 (1H, s, H-1); 10.10 (1H, s, 3-OH). Found, %: C 78.67; H 4.65. C₂₅H₁₈O₄. Calculated, %: C 78.52; H 4.74.

2-Oxo-1,2-diphenylethyl Ester of 3-Hydroxy-7-methoxy-2-naphthoic Acid (8b). Yield 74%; mp 159–160 °C (2-propanol–toluene, 2:1). ¹H NMR spectrum, δ, ppm (J, Hz): 3.86 (3H, s, 7-OCH₃); 7.08 (1H, d, J = 2.4, H-8); 7.15 (1H, s, 2-COOCH); 7.17 (1H, dd, J = 8.8, J = 2.4, H-6); 7.25 (1H, s, H-4); 7.40–7.46 (5H, m, H Ph); 7.52–7.62 (4H, m, H-5, H Ph); 7.98–8.01 (2H, m, H Ph); 8.51 (1H, s, H-1); 9.92 (1H, s, 3-OH). Found, %: C 75.90; H 4.95. C₂₆H₂₀O₅. Calculated, %: C 75.72; H 4.89.

3-(4,5-Diphenyl-1,3-oxazol-2-yl)-2-naphthols 5a,b (General Method). A mixture of desyl naphthoate 8a,b (20 mmol), ammonium acetate (9.24 g, 120 mmol), and acetic acid (40 ml) was boiled for 4 h. The mixture was poured into ice (500 g), and the precipitate was filtered off, washed with water, and dried. The obtained naphthols 5a,b were recrystallized from a mixture of 2-propanol and toluene.

3-(4,5-Diphenyl-1,3-oxazol-2-yl)-2-naphthol (5a). Yield 69%; mp 154–155 °C (2-propanol–toluene, 3:1). ¹H NMR spectrum, δ, ppm (J, Hz): 7.35 (1H, m, H-7); 7.40–7.45 (7H, m, H-1, H Ph); 7.48 (1H, m, H-6); 7.71–7.77 (5H, m, H-5, H Ph); 7.86 (1H, d, J = 8.4, H-8); 8.49 (1H, s, H-4); 11.15 (1H, s, 2-OH). Found, %: C 82.75; H 4.79; N 3.76. C₂₅H₁₇NO₂. Calculated, %: C 82.63; H 4.71; N 3.85.

3-(4,5-Diphenyl-1,3-oxazol-2-yl)-6-methoxy-2-naphthol (5b). Yield 72%; mp 194–195.5 °C (2-propanol– toluene, 1:1). ¹H NMR spectrum, δ, ppm (J, Hz): 3.90 (3H, s, 6-OCH₃); 7.14 (1H, d, J = 2.6, H-5); 7.15 (1H, dd, J = 9.7, J = 2.6, H-7); 7.37 (1H, s, H-1); 7.39–7.46 (6H, m, H Ph); 7.61 (1H, d, J = 9.7, H-8); 7.70-7.75 (4H, m, H Ph); 8.37 (1H, s, H-4); 10.95 (1H, s, 2-OH). Found, %: C 79.48; H 4.95; N 3.50. C₂₆H₁₉NO₃. Calculated, %: C 79.37; H 4.87; N 3.56.

2-Hydroxy-3-(4,5-diphenyl-1,3-oxazol-2-yl)-1-naphthaldehydes 3a,b (General Method). A mixture of the naphthol 5a,b (10 mmol), hexamethylenetetramine (2.80 g, 20 mmol), and acetic acid (40 ml) was stirred at 95–100 °C for 5 h 30 min. A mixture of conc. HCl (15 ml) and water (18 ml) was added, and the reaction mixture was stirred at 95–100 °C for 1 h. It was poured into 175 ml of water, and the precipitate was filtered off, washed with water, and dried. The obtained aldehydes 3a,b were purified by column chromatography on Al₂O₃ (eluent chloroform) and recrystallized from a 2:1 mixture of benzene and acetonitrile.

2-Hydroxy-3-(4,5-diphenyl-1,3-oxazol-2-yl)-1-naphthaldehyde (3a). Yield 51%; mp 213–214 °C. The ¹H NMR spectrum of the obtained compound was identical with the spectrum of the compound obtained earlier [17]. Found, %: C 79.67; H 4.24; N 3.70. C₂₆H₁₇NO₃. Calculated, %: C 79.78; H 4.38; N 3.58.

2-Hydroxy-3-(4,5-diphenyl-1,3-oxazol-2-yl)-6-methoxy-1-naphthaldehyde (3b). Yield 38%; mp 217.5–218.5 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 3.93 (3H, s, 6-OCH₃); 7.18 (1H, d, J = 2.7, H-5); 7.34 (1H, dd, J = 9.5, J = 2.7, H-7); 7.41–7.49 (6H, m, H Ph); 7.71–7.76 (4H, m, H Ph); 8.58 (1H, s, H-4); 9.19 (1H, d, J = 9.5, H-8); 11.02 (1H, s, 1-CHO); 12.22 (1H, s, 2-OH). Found, %: C 76.80; H 4.65; N 3.43. C₂₇H₁₉NO₄. Calculated, %: C 76.95; H 4.54; N 3.32.

3',3'-Dimethyl-5-(4,5-diphenyl-1,3-oxazol-2-yl)spiro[benzo[ f ]chromene-3,2'-indolines] 1a–h (General Method). A. A mixture of the 3H-indolium salt 2a–d (1 mmol), aldehyde 3a,b (1 mmol), and glacial acetic acid (8 ml) was boiled for 5 h 30 min and kept at ~20 °C for 12 h. The precipitate was filtered off, washed with ether, dried, and then used without further purification. Dry ammonia was passed into a suspension of the obtained salt 4a–h in benzene (20 ml), the solvent was evaporated, and the residue was purified by column chromatography on Al₂O₃ (eluent benzene). The spiropyrans 1a–h were recrystallized from a 2:1 mixture of heptane and toluene.

3',3'-Dimethyl-5-(4,5-diphenyl-1,3-oxazol-2-yl)spiro[benzo[ f ]chromene-3,2'-indolines] 1i–o (General Method). B. A mixture of the 3H-indolium salt 2e–h (1 mmol), triethylamine (0.14 ml, 1 mmol), and aldehyde 3a,b (1 mmol) in benzene (8 ml) and 2-propanol (2 ml) was boiled for 10 h and evaporated. The residue was purified by column chromatography on Al₂O₃ (eluent benzene). The spiropyrans 1i–o were recrystallized from a 3:1 mixture of isooctane and toluene.

5'-Chloro-5-(4,5-diphenyl-1,3-oxazol-2-yl)-1',3',3'-trimethylspiro[benzo[ f ]chromene-3,2'-indoline] (1a). Yield 50%; mp 219.5–221 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.26 (3H, s, 3'-CH₃); 1.43 (3H, s, 3'-CH₃); 2.77 (3H, s, 1'-CH₃); 5.88 (1H, d, J = 10.5, H-2); 6.45 (1H, d, J = 8.2, H-7'); 7.08 (1H, d, J = 2.1, H-4'); 7.13 (1H, dd, J = 8.2, J = 2.1, H-6'); 7.15–7.19 (2H, m, H Ph); 7.30–7.42 (7H, m, H-8, H Ph); 7.57 (1H, dd, J = 8.5, J = 6.9, J = 1.4, H-9); 7.59–7.62 (2H, m, H Ph); 7.68 (1H, d, J = 10.5, H-1); 7.87 (1H, d, J = 8.1, H-7); 8.05 (1H, d, J = 8.5, H-10); 8.62 (1H, s, H-6). Found, %: C 78.68; H 5.15; N 4.89. C₃₈H₂₉ClN₂O₂. Calculated, %: C 78.54; H 5.03; N 4.82.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-1',3',3',5'-tetramethylspiro[benzo[ f ]chromene-3,2'-indoline] (1b). Yield 43%; mp 222–223 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.25 (3H, s, 3'-CH₃); 1.41 (3H, s, 3'-CH₃); 2.34 (3H, s, 5'-CH₃); 2.78 (3H, s, 1'-CH₃); 5.90 (1H, d, J = 10.5, H-2); 6.47 (1H, d, J = 7.8, H-7'); 6.93 (1H, m, H-4'); 7.00 (1H, m, H-6'); 7.13–7.16 (2H, m, H Ph); 7.21–7.29 (3H, m, H Ph); 7.31–7.41 (4H, m, H-8, H Ph); 7.56 (1H, ddd, J = 8.4, J = 6.9, J = 1.4, H-9); 7.61–7.64 (2H, m, H Ph); 7.65 (1H, d, J = 10.5, H-1); 7.86 (1H, d, J = 8.1, H-7); 8.05 (1H, d, J = 8.5, H-10); 8.60 (1H, s, H-6). Found, %: C 83.37; H 5.83; N 5.09. C₃₉H₃₂N₂O₂. Calculated, %: C 83.54; H 5.75; N 5.00.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-1',3',3'-trimethyl-5'-methoxyspiro[benzo[f]chromene-3,2'-indoline] (1c). Yield 42%; mp 192.5–193.5 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.27 (3H, s, 3'-CH₃); 1.43 (3H, s, 3'-CH₃); 2.74 (3H, s, 1'-CH₃); 3.79 (3H, s, 5-OCH₃); 5.90 (1H, d, J = 10.5, H-2); 6.46 (1H, d, J = 8.3, H-7'); 6.71 (1H, dd, J = 8.3, J = 2.4, H-6'); 6.78 (1H, d, J = 2.4, H-4'); 7.12–7.16 (2H, m, H Ph); 7.26–7.40 (7H, m, H-8, H Ph); 7.56 (1H, ddd, J = 8.4, J = 6.9, J = 1.4, H-9); 7.61–7.64 (2H, m, H Ph); 7.66 (1H, d, J = 10.5, H-1); 7.86 (1H, d, J = 8.1, H-7); 8.05 (1H, d, J = 8.5, H-10); 8.62 (1H, s, H-6). Found, %: C 81.37; H 5.46; N 4.75. C₃₉H₃₂N₂O₃. Calculated, %: C 81.23; H 5.59; N 4.86.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-3',3'-dimethyl-1'-propylspiro[benzo[ f ]chromene-3,2'-indoline] (1 d). Yield 45%; mp 159.5–161 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 0.84 (3H, t, J = 7.4, 1'-CH₂CH₂CH ₃); 1.25 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 1.65 (2H, m, 1'-CH₂CH ₂CH₃); 3.25 (2H, m, 1-CH ₂CH₂CH₃); 5.89 (1H, d, J = 10.5, H-2); 6.58 (1H, d, J = 7.7, H-7'); 6.87 (1H, td, J = 7.4, J = 0.9, H-5'); 7.09–7.13 (3H, m, H-4', H Ph); 7.21 (1H, dt, J = 7.6, J = 1.2, H-6'); 7.23–7.27 (3H, m, H Ph); 7.31–7.40 (4H, m, H-8, H Ph); 7.56 (1H, ddd, J = 8.3, J = 6.9, J = 1.3, H-9); 7.60–7.64 (3H, m, H-1, H Ph); 7.86 (1H, d, J = 8.1, H-7); 8.05 (1H, d, J = 8.5, H-10); 8.61 (1H, s, H-6). Found, %: C 83.45; H 6.03; N 4.98. C₄₀H₃₄N₂O₂. Calculated, %: C 83.60; H 5.96; N 4.87.

5'-Chloro-5-(4,5-diphenyl-1,3-oxazol-2-yl)-8-methoxy-1',3',3'-trimethylspiro[benzo[f]chromene- 3,2'-indoline] (1e). Yield 46%; mp 225–226 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.26 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 2.76 (3H, s, 1'-CH₃); 3.92 (3H, s, 8-OCH₃); 5.87 (1H, d, J = 10.5, H-2); 6.44 (1H, d, J = 8.2, H-7'); 7.08 (1H, d, J = 2.1, H-4'); 7.14 (1H, dd, J = 8.1, J = 2.1, H-6'); 7.15–7.18 (3H, m, H-7, H Ph); 7.25 (1H, dd, J = 9.2, J = 2.7, H-9); 7.29–7.41 (6H, m, H Ph); 7.60–7.64 (3H, m, H-1, H Ph); 7.96 (1H, d, J = 9.2, H-10); 8.53 (1H, s, H-6). Found, %: C 76.54; H 5.25; N 4.66. C₃₉H₃₁ClN₂O₃. Calculated, %: C 76.65; H 5.11; N 4.58.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-8-methoxy-1',3',3',5'-tetramethylspiro[benzo[ f ]chromene-3,2'-indo- line] (1f). Yield 46%; mp 241–242 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.25 (3H, s, 3'-CH₃); 1.41 (3H, s, 3'-CH₃); 2.34 (3H, s, 5'-CH₃); 2.77 (3H, s, 1'-CH₃); 3.91 (3H, s, 8-OCH₃); 5.89 (1H, d, J = 10.5, H-2); 6.46 (1H, d, J = 7.8, H-7'); 6.93 (1H, d, J = 1.6, H-4'); 7.00 (1H, m, H-6'); 7.13–7.18 (3H, m, H-7, H Ph); 7.20–7.28 (4H, m, H-9, H Ph); 7.30–7.39 (3H, m, H Ph); 7.61–7.64 (2H, m, H Ph); 7.59 (1H, d, J = 10.5, H-1); 7.96 (1H, d, J = 9.3, H-10); 8.51 (1H, s, H-6). Found, %: C 81.17; H 5.69; N 4.85. C₄₀H₃₄N₂O₃. Calculated, %: C 81.33; H 5.80; N 4.74.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-5',8-dimethoxy-1',3',3'-trimethylspiro[benzo[ f ]chromene-3,2'-indo- line] (1 g). Yield 47%; mp 231–232 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.27 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 2.73 (3H, s, 1'-CH₃); 3.79 (3H, s, 5'-OCH₃); 3.92 (3H, s, 8-OCH₃); 5.90 (1H, d, J = 10.5, H-2); 6.45 (1H, d, J = 8.3, H-7'); 6.72 (1H, dd, J = 8.3, J = 2.6, H-6'); 6.78 (1H, d, J = 2.6, H-4'); 7.12–7.18 (3H, m, H-7, H Ph); 7.21–7.29 (4H, m, H-9, H Ph); 7.31–7.40 (3H, m, H Ph); 7.58–7.65 (3H, m, H-1, H Ph); 7.96 (1H, d, J = 9.2, H-10); 8.53 (1H, s, H-6). Found, %: C 79.05; H 5.74; N 4.73. C₄₀H₃₄N₂O₄. Calculated, %: C 79.19; H 5.65; N 4.62.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-8-methoxy-3',3'-dimethyl-1'-propylspiro[benzo[f]chromene-3,2'-indo- line] (1 h). Yield 45%; mp 229–230 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 0.84 (3H, t, J = 7.4, 1'-CH₂CH₂CH ₃); 1.24 (3H, s, 3'-CH₃); 1.41 (3H, s, 3'-CH₃); 1.64 (2H, m, 1'-CH₂CH ₂CH₃); 3.24 (2H, m, 1'-CH ₂CH₂CH₃); 3.92 (3H, s, 8-OCH₃); 5.89 (1H, d, J = 10.5, H-2); 6.58 (1H, d, J = 7.7, H-7'); 6.87 (1H, td, J = 7.4, J = 0.9, H-5'); 7.08–7.18 (4H, m, H-4',7, H Ph); 7.19–7.27 (5H, m, H-6',9, H Ph); 7.31–7.39 (3H, m, H Ph); 7.57 (1H, d, J = 10.5, H-1); 7.61–7.64 (2H, m, H Ph); 7.95 (1H, d, J = 9.2, H-10); 8.52 (1H, s, H-6). Found, %: C 81.25; H 5.91; N 4.76. C₄₁H₃₆N₂O₃. Calculated, %: C 81.43; H 6.00; N 4.63.

1'-Allyl-5-(4,5-diphenyl-1,3-oxazol-2-yl)-3',3'-dimethylspiro[benzo[ f ]chromene-3,2'-indoline] (1i). Yield 44%; mp 179–180 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.29 (3H, s, 3'-CH₃); 1.44 (3H, s, 3'-CH₃); 3.80 (1H, ddt, J = 17.3, J = 5.3, J = 1.6, 1'-CH ₂CH = CH₂); 4.04 (1H, ddt, J = 17.3, J = 4.2, J = 2.0, 1'-CH ₂CH = CH₂); 4.99 (1H, dq, J = 10.3, J = 1.7, 1'-CH₂CH = CH ₂); 5.15 (1H, dq, J = 17.2, J = 1.8, 1'-CH₂CH = CH ₂); 5.89 (1H, m, 1'-CH₂CH = CH₂); 5.90 (1H, d, J = 10.5, H-2); 6.59 (1H, d, J = 7.7, H-7'); 6.90 (1H, td, J = 7.4, J = 0.9, H-5'); 7.09–7.16 (3H, m, H-4', H Ph); 7.20 (1H, td, J = 7.6, J = 1.3, H-6'); 7.23–7.26 (3H, m, H Ph); 7.31–7.41 (4H, m, H-8, H Ph); 7.56 (1H, ddd, J = 8.4, J = 6.9, J = 1.4, H-9); 7.60–7.65 (3H, m, H-1, H Ph); 7.86 (1H, d, J = 8.1, H-7); 8.04 (1H, d, J = 8.5, H-10); 8.61 (1H, s, H-6). Found, %: C 83.74; H 5.69; N 4.80. C₄₀H₃₂N₂O₂. Calculated, %: C 83.89; H 5.63; N 4.89.

1'-Allyl-5-(4,5-diphenyl-1,3-oxazol-2-yl)-5'-methoxy-3',3'-dimethylspiro[benzo[ f ]chromene-3,2'-indo- line] (1j). Yield 60%; mp 195–196.5 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.29 (3H, s, 3'-CH₃); 1.43 (3H, s, 3'-CH₃); 3.72 (1H, ddt, J = 17.2, J = 5.4, J = 1.6, 1'-CH ₂CH = CH₂); 3.78 (3H, s, 5'-OCH₃); 3.98 (1H, ddt, J = 17.2, J = 4.5, J = 2.1, 1'-CH ₂CH = CH₂); 4.98 (1H, dq, J = 10.3, J = 1.7, 1'-CH₂CH = CH ₂); 5.14 (1H, dq, J = 17.2, J = 1.7, 1'-CH₂CH = CH ₂); 5.88 (1H, m, 1'-CH₂CH = CH₂); 5.90 (1H, d, J = 10.5, H-2); 6.48 (1H, d, J = 8.4, H-7'); 6.69 (1H, dd, J = 8.4, J = 2.6, H-6'); 6.78 (1H, d, J = 2.6, H-4'); 7.12–7.17 (2H, m, H Ph); 7.24-7.28 (3H, m, H Ph); 7.32–7.40 (4H, m, H-8, H Ph); 7.55 (1H, ddd, J = 8.4, J = 6.9, J = 1.4, H-9); 7.60–7.65 (3H, m, H-1, H Ph); 7.86 (1H, dd, J = 8.2, J = 1.3, H-7); 8.03 (1H, d, J = 8.5, H-10); 8.61 (1H, s, H-6). Found, %: C 81.54; H 5.60; N 4.56. C₄₁H₃₄N₂O₃. Calculated, %: C 81.70; H 5.69; N 4.65.

5'-Allyloxy-5-(4,5-diphenyl-1,3-oxazol-2-yl)-1',3',3'-trimethylspiro[benzo[f]chromene-3,2'-indo-line] (1 k). Yield 50%; mp 188–189.5 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.27 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 2.74 (3H, s, 1'-CH₃); 4.46 (2H, ddd, J = 5.4, J = 2.6, J = 1.3, 5'-OCH ₂CH = CH₂); 5.28 (1H, dq, J = 10.4, J = 1.4, 5'-OCH₂CH = CH ₂); 5.44 (1H, dq, J = 17.2, J = 1.6, 5'-OCH₂CH = CH ₂); 5.90 (1H, d, J = 10.5, H-2); 6.10 (1H, ddt, J = 17.2, J = 10.6, J = 5.3, 5'-OCH₂CH = CH₂); 6.44 (1H, d, J = 8.3, H-7'); 6.73 (1H, dd, J = 8.3, J = 2.5, H-6'); 6.80 (1H, d, J = 2.5, H-4'); 7.14–7.18 (2H, m, H Ph); 7.26–7.40 (7H, m, H-8, H Ph); 7.56 (1H, ddd, J = 1.4, J = 6.8, J = 8.4, H-9); 7.61–7.64 (2H, m, H Ph); 7.66 (1H, d, J = 10.5, H-1); 7.86 (1H, d, J = 8.1, H-7); 8.05 (1H, d, J = 8.5, H-10); 8.62 (1H, s, H-6). Found, %: C 81.59; H 5.81; N 4.59. C₄₁H₃₄N₂O₃. Calculated, %: C 81.70; H 5.69; N 4.65.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-1'-isobutyl-3,3-dimethylspiro[benzo[ f ]chromene-3,2'-indoline] (1 l). Yield 38%; mp 180–181 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 0.87 (3H, d, J = 6.7, 1'-CH₂CH(CH ₃)₂); 0.91 (3H, d, J = 6.6, 1'-CH₂CH(CH ₃)₂); 1.27 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 2.06 (1H, m, 1'-CH ₂CH(CH₃)₂); 3.00 (1H, dd, J = 14.4, J = 8.8, 1'-CH ₂CH(CH₃)₂); 3.06 (1H, dd, J = 14.4, J = 6.3, 1'-CH ₂CH(CH₃)₂); 5.92 (1H, d, J = 10.6, H-2); 6.57 (1H, d, J = 7.8, H-7'); 6.87 (1H, td, J = 7.4, J = 0.9, H-5'); 7.09–7.14 (3H, m, H-4', H Ph); 7.18 (1H, td, J = 7.6, J = 1.3, H-6'); 7.24–7.29 (3H, m, H Ph); 7.31–7.40 (4H, m, H-8, H Ph); 7.56 (1H, ddd, J = 8.4, J = 6.9, J = 1.4, H-9); 7.59–7.63 (3H, m, H-1, H Ph); 7.85 (1H, d, J = 8.1, H-7); 8.04 (1H, d, J = 8.5, H-10); 8.58 (1H, s, H-6). Found, %: C 83.77; H 6.09; N 4.64. C₄₁H₃₆N₂O₂. Calculated, %: C 83.64; H 6.16; N 4.76.

1'-Allyl-5-(4,5-diphenyl-1,3-oxazol-2-yl)-3',3'-dimethyl-8-methoxyspiro[benzo[ f ]chromene-3,2'-indo- line] (1 m). Yield 40%; mp 212.5–214 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.28 (3H, s, 3'-CH₃); 1.43 (3H, s, 3'-CH₃); 3.79 (1H, ddt, J = 17.3, J = 5.2, J = 1.7, 1'-CH ₂CH = CH₂); 3.92 (3H, s, 8-OCH₃); 4.04 (1H, ddt, J = 17.3, J = 4.2, J = 2.0, 1'-CH ₂CH = CH₂); 4.98 (1H, dq, J = 10.3, J = 1.7, 1'-CH₂CH = CH ₂); 5.14 (1H, dq, J = 17.2, J = 1.8, 1'-CH₂CH = CH ₂); 5.89 (1H, m, 1'-CH₂CH = CH₂); 5.90 (1H, d, J = 10.5, H-2); 6.58 (1H, d, J = 7.7, H-7'); 6.89 (1H, td, J = 7.4, J = 0.9, H-5'); 7.09–7.18 (4H, m, H-4',7, H Ph); 7.19–7.26 (5H, m, H-6',9, H Ph); 7.31–7.39 (3H, m, H Ph); 7.57 (1H, d, J = 10.5, H-1); 7.60–7.64 (2H, m, H Ph); 7.94 (1H, d, J = 9.3, H-10); 8.52 (1H, s, H-6). Found, %: C 81.56; H 5.77; N 4.76. C₄₁H₃₄N₂O₃. Calculated, %: C 81.70; H 5.69; N 4.65.

1'-Allyl-5-(4,5-diphenyl-1,3-oxazol-2-yl)-5',8-dimethoxy-3',3'-dimethylspiro[benzo[ f ]chromene-3,2'-indoline] (1n). Yield 41%; mp 221–222.5 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 1.28 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 3.71 (1H, ddt, J = 17.2, J = 5.4, J = 1.6, 1'-CH ₂CH = CH₂); 3.78 (3H, s, 5'-OCH₃); 3.92 (3H, s, 8-OCH₃); 3.97 (1H, ddt, J = 17.2, J = 4.4, J = 2.1, 1'-CH ₂CH = CH₂); 4.98 (1H, dq, J = 10.2, J = 1.7, 1'-CH₂CH = CH ₂); 5.14 (1H, dq, J = 17.2, J = 1.7, 1'-CH₂CH = CH ₂); 5.88 (1H, m, 1'-CH₂CH = CH₂); 5.89 (1H, d, J = 10.5, H-2); 6.48 (1H, d, J = 8.4, H-7'); 6.69 (1H, dd, J = 2.6, J = 8.4, H-6'); 6.78 (1H, d, J = 2.5, H-4'); 7.12-7.18 (3H, m, H-7, H Ph); 7.21–7.40 (7H, m, H-9, H Ph); 7.57 (1H, d, J = 10.5, H-1); 7.62–7.65 (2H, m, H Ph); 7.94 (1H, d, J = 9.3, H-10); 8.52 (1H, s, H-6). Found, %: C 79.65; H 5.90; N 4.47. C₄₂H₃₆N₂O₄. Calculated, %: C 79.72; H 5.73; N 4.43.

5-(4,5-Diphenyl-1,3-oxazol-2-yl)-1'-isobutyl-8-methoxy-3',3'-dimethylspiro[benzo[f]chromene-3,2'-indoline] (1o). Yield 39%; mp 204–205 °C. ¹H NMR spectrum, δ, ppm (J, Hz): 0.88 (3H, d, J = 6.7, 1'-CH₂CH(CH ₃)₂); 0.91 (3H, d, J = 6.6, 1'-CH₂CH(CH ₃)₂); 1.27 (3H, s, 3'-CH₃); 1.42 (3H, s, 3'-CH₃); 2.06 (1H, m, 1'-CH₂CH(CH₃)₂); 3.00 (1H, dd, J = 14.5, J = 8.8, 1'-CH ₂CH(CH₃)₂); 3.06 (1H, dd, J = 14.5, J = 6.4, 1'-CH ₂CH(CH₃)₂); 3.92 (3H, s, 8-OCH₃); 5.92 (1H, d, J = 10.5, H-2); 6.58 (1H, d, J = 7.8, H-7'); 6.87 (1H, dt, J = 7.4, J = 0.9, H-5'); 7.10–7.18 (4H, m, H-4',7, H Ph); 7.19–7.28 (5H, m, H-6',9, H Ph); 7.31–7.39 (3H, m, H Ph); 7.56 (1H, d, J = 10.5, H-1); 7.60–7.63 (2H, m, H Ph); 7.95 (1H, d, J = 9.2, H-10); 8.50 (1H, s, H-6). Found, %: C 81.68; H 6.11; N 4.41. C₄₂H₃₈N₂O₃. Calculated, %: C 81.53; H 6.19; N 4.53.

The work was carried out with financial support from the Ministry of Education and Science of the Rus-sian Federation (Federal Target Program “Scientific and Scientific-Pedagogical Staff of Innovative Russia, 2009–2013, State contract No. P2435).