# Photooxygenations and Self-Sensitizations of Naphthylamines: Efficient Access to Iminoquinones

Authors: Ying Wei; Lei Tang; Chunxiao Zhong; Xinmiao Xie; Pengju Sun; Chen Sun; He Zhang; Xiang-ping Zheng; Xiuli Wang; Ling-hai Xie
Journal: Journal of Chemistry
 (2018)

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## Abstract

A series of spiro [fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (SFDBAO) derivatives have been concisely and cleanly obtained by exposure to sunlight without external photosensitizers in the higher yields than that when using a UV lamp. An interesting autocatalyst and self-sensitive procedure have been proposed to explain the effective photooxygenation. SFDBAO derivatives exhibit the continuousπ-stacks in single-crystal and electron-withdraw properties with red light-emitting and photovoltaic properties.


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## Body

## 1. Introduction

Iminoquinones constitute the core structures of many naturally occurring compounds and display important antineoplastic, antifungal, and antibacterial activities (Figure1) [1–4]. Commonly used approaches for the construction of iminoquinones include (i) metal catalysis [5–7], (ii) photosynthesis by UV lamps and photosensitizers [7], (iii) 2-iodoxybenzoic acid [IBX, 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide] oxidation [8, 9], and (iv) Dess–Martin periodinane [DMP, 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one]-mediated oxidative reaction [10]. Although the aforementioned elegant methods appear to be general and efficient, further development of the low-cost and eco-friendly methods that allow the facile assembly of highly functionalized iminoquinone from readily available and simple starting materials is still required, because they have wide range of applications in medicine and biology.Figure 1
Bioactive molecules containing iminoquinone constitute the core structures.Herein, we report a photochemical strategy for generating excited state species from naphthylamines, which does not rely upon any metal- or organic-based photoredox catalysts (Scheme1). The reaction, which occurs at ambient temperature and requires irradiation by sunlight in order to proceed, is sufficient for achieving iminoquinones with synthetically useful results. In general, most photooxygenations require the effective photocatalysis or photosensitizers such as, Ir or Ru complexes [11], rose bengal [12–14], porphyrins [15], 9-mesityl-10-methylacridinium [16, 17], inorganic TiO2 [18, 19], or organic molecule [20]. However, our visible light mediates photooxygenation of naphthylamines with the advantages of high chemoselectivity without any external photosensitizers. In this reaction, naphthylamines play a dual role of providing both photosensitizer and substrate, and O2 functions as triplet state trapping agent and oxygen sources.Scheme 1
Photooxygenations and self-sensitizations of naphthylamine strategies. (a) Previous work [4]. (b) Our work.
(a)
(b)Spirofluorenes are widely used in semiconductors, including OLEDs, PLEDs, solar cells, fuel cells, memories, and so on [21]. Common electron-rich spirofluorenes include spirobifluorenes, spirofluoreneacridines, spirobisindane, spirofluorenexanthenes, spiropyran, and so on. Till now, electron-deficient spirofluorenes have not been synthesized and reported because of the lack of convenient and efficient synthetic route. Therefore, we describe a novel strategy for the one-pot synthesis of electron-deficient 5H-spiro[dibenzo[c,h]a-crdine-7,9′-fluoren]-5-one (SFDBAO) through a photooxygenation-initiated cascade process.


## 2. Experimental

### 2.1. Reagents and Instruments

All the reagents used were of analytical pure. The UV lamp irradiation is carried out indoors by a household 23 W compact fluorescent light (CFL) bulb.1H and 13C NMR spectra were performed on a Bruker 400 MHz spectrometer in CDCl3 or DMSO-d6 with tetramethylsilane (TMS) as the interval standard. Mass spectra were recorded on a Shimadzu GCMS-QP2010 plus equipped with DB-5 ms column or a Shimadzu AXIMA-CFR plus spectrometer. For the MALDI-TOF MS spectra, the spectra were recorded in reflective mode, and substrates were used. Molecular weights of the samples were measured by gel permeation chromatography (GPC) on a Shimadzu LC-20A HPLC system equipped with 7911GP-502 and GPNXC columns. Elemental analyses were carried out in an Elementar Analysensysteme GmbH-vario EL III element analyzer. Absorption spectra were measured with a Shimadzu UV-3600 spectrometer at 25°C, and emission spectra were recorded on a Shimadzu RF-5301(PC)S luminescence spectrometer. Cyclic voltammetric (CV) studies were conducted using a CHI660C electrochemical workstation in a typical three-electrode cell with a platinum sheet working electrode, a platinum wire counter electrode, and a silver/silver nitrate (Ag/Ag+) reference electrode. X-ray crystallographic data were collected at 293 K on a P4 Bruker diffractometer equipped with a fine-focus sealed tube and a rotating anode utilizing graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Data processing was carried out using the program SAINT, while the program SADABS was utilized for the scaling of diffraction data, the application of a decay correction, and an empirical absorption correction based on redundant reflections. The structures were solved by direct methods and refined against F2 with the full-matrix, least-squares methods using SHELXS-97 and SHELXL-97, respectively. Column chromatography purification was carried out using the silica gel (200–300 mesh).


### 2.2. Syntheses of the Intermediates and the Target Compounds

#### 2.2.1. General Procedure for Preparation of2 and 3

In a round bottom flask, compound1 (2 mmol) was dissolved in MeCN (400 mL) and the mixture was stirred in the sunlight irradiation under air atmosphere for 6 hours to produce compound 2. The crude product was purified by flash column chromatography (silica gel, CH2Cl2/petroleum ether, 1: 3) to give purified products.(1) Spiro[fluorene-9,7′-dibenzo[c,h]acridi-ne]-5′-one (SFDBAO, 2a). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) to give 2a (0.69 g, 1.56 mmol) as a red solid with the yield of 78%. GC-MS (EI-m/z) calcd for C33H19NO+ [M]+ 445.15, found 445.00. 1H NMR (400 MHz, CDCl3, ppm): δ 9.28–9.26 (d, J = 8.4 Hz, 1H), 9.06–9.04 (d, J = 8.8 Hz, 1H), 8.14–8.12 (d, J = 8.8 Hz, 1H), 7.87–7.84 (m, 3H), 7.76–7.73 (t, J = 9.2 Hz, 2H), 7.68–7.64 (t, J = 8.4 Hz, 1H), 7.61–7.57 (t, J = 7.6 Hz, 1H), 7.55–7.53 (d, J = 8.4 Hz, 1H), 7.45–7.41 (t, J = 7.6 Hz, 2H), 7.22–7.18 (t, J = 7.6 Hz, 2H), 7.04–7.02 (d, J = 7.6 Hz, 2H), 6.57–6.55 (d, J = 8.8 Hz, 1H), 6.04 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 184.5, 151.7, 150.0, 145.4, 140.8, 137.8, 135.6, 133.6, 132.7, 132.2, 131.4, 130.8, 130.3, 128.9, 128.8, 128.6, 127.7, 127.2, 126.7, 125.9, 125.3, 124.8, 124.6, 123.8, 120.7, 57.7. Anal. Calcd for C33H19NO: C, 89.04; H, 4.30; N, 3.15. Found: C, 89.07; H, 4.28; N, 3.18.(2) 9′-Chlorospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (ClSFDBAO, 2b). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) and CCl4 (400 mL). Purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to give 2b (0.785 g, 1.64 mmol) as a red solid with the yield of 82%. GC-MS (EI-m/z) calcd for C33H18ClNO+ [M]+ 479.11, found 479.05. 1H NMR (400 MHz, CDCl3, ppm): δ 9.32–9.29 (d, J = 7.6 Hz, 1H), 9.02–9.00 (d, J = 8.0 Hz, 1H), 8.21–8.19 (d, J = 8.4 Hz, 1H), 8.13–8.11 (d, J = 7.6 Hz, 1H), 7.88–7.86 (d, J = 7.6 Hz, 3H), 7.84–7.79 (m, 1H), 7.72–7.66 (m, 2H), 7.47–7.43 (t, J = 7.4 Hz, 2H), 7.24–7.20 (t, J = 7.4 Hz, 2H), 7.04–7.02 (d, J = 7.6 Hz, 2H), 6.64 (s, 1H), 6.02 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): 13C NMR (100 MHz, CDCl3): δ 184.4, 151.1, 150.3, 145.0, 140.7, 137.0, 135.4, 133.8, 133.2, 132.8, 131.4, 130.9, 130.9, 130.4, 129.2, 129.0, 128.9, 127.9, 127.7, 126.0, 125.3, 124.8, 124.4, 124.2, 120.9, 57.5. Anal. Calcd for C33H18ClNO: C, 82.73; H, 3.79; N, 2.92. Found: C, 82.76; H, 3.77; N, 2.90.(3) 2-Bromospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (BrSFDBAO, 2c). This compound was prepared following the general procedures by applying 1c (1.02 g, 2 mmol) to give 2c (0.765 g, 1.46 mmol) as a red solid with the yield of 73%. GC-MS (EI-m/z) calcd for C33H18BrNO+ [M]+ 523.06, found 522.85. 1H NMR (400 MHz, CDCl3, ppm): δ 9.27–9.25 (d, J = 8.4 Hz, 1H), 9.05–9.03 (d, J = 7.6 Hz, 1H), 8.14–8.12 (d, J = 8.4 Hz, 1H), 7.89–7.95 (t, J = 7.6 Hz, 1H), 7.84–7.82 (d, J = 7.6 Hz, 1H), 7.80–7.75 (m, 2H), 7.75–7.67 (m, 2H), 7.62–7.54 (m, 3H), 7.46–7.42 (t, J = 7.6 Hz, 1H), 7.25–7.21 (t, J = 7.4 Hz, 1H), 7.14 (s, 1H), 7.03–7.01 (d, J = 7.6 Hz, 1H), 6.55–6.53 (d, J = 8.4 Hz, 1H), 6.02 (s, 1H). 13C NMR (101 MHz, CDCl3): δ 184.4, 153.5, 151.5, 149.9, 144.4, 139.7, 139.7, 137.8, 135.5, 133.7, 132.9, 132.2, 131.9, 131.3, 130.9, 130.5, 130., 129.4, 128.9, 128.0, 127.8, 127.7, 127.4, 126.9, 126.0, 125.4, 124.9, 124.4, 123.8, 122.2, 122.1, 120.7, 57.5. Anal. Calcd for C33H18BrNO: C, 75.78; H, 3.47; N, 2.68. Found: C, 75.81; H, 3.45; N, 2.66.(4) 2,7-Dibromospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (DBrSFDBAO, 2d). This compound was prepared following the general procedures by applying 1d (1.18 g, 2 mmol) to give 2d (0.844 g, 1.40 mmol) a red solid with the yield of 70%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.26–9.24 (d, J = 8.4 Hz, 1H), 9.05–9.03 (d, J = 7.6 Hz, 1H), 8.15–8.13 (d, J = 8.8 Hz, 1H), 7.90–7.86 (t, J = 7.6 Hz, 1H), 7.79–7.76 (m, 2H), 7.70–7.68 (d, J = 8.4 Hz, 3H), 7.64–7.58 (m, 2H), 7.57–7.55 (dd, J = 8.2, 1.8 Hz, 2H), 7.14–7.14 (d, J = 1.6 Hz, 2H), 6.53–6.51 (d, J = 8.8 Hz, 1H), 6.01 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.3, 153.4, 149.7, 143.4, 138.6, 137.7, 135.3, 133.8, 133.0, 132.2, 132.1, 131.3, 131.0, 130.8, 130.6, 128.1, 127.8, 127.5, 127.1, 126.5, 126.0, 125.5, 124.2, 123.9, 122.8, 122.1, 57.3. Anal. Calcd for C33H17Br2NO: C, 65.95; H, 2.85; N, 2.33. Found: C, 65.92; H, 2.86; N, 2.35.(5) (Z)-4-(Naphthalen-1-ylimino)naphthalen-1(4H)-one (NINO, 2e). This compound was prepared following the general procedures by applying 1e (0.538 g, 2 mmol) to give 2e (0.463 g, 1.64 mmol) as a red solid with the yield of 82%. GC-MS (EI-m/z) calcd for C20H13NO+ [M]+ 283.10, found 282.95. 1H NMR (400 MHz, CDCl3, ppm): δ 8.68–8.66 (d, J = 8.4 Hz, 1H), 8.23–8.21 (d, J = 7.6 Hz, 1H), 7.91–7.88 (d, J = 8.8 Hz, 2H), 7.83–7.79 (t, J = 7.6 Hz, 1H), 7.75–7.73 (d, J = 8.0 Hz, 2H), 7.57–7.53 (t, J = 7.6 Hz, 1H), 7.51–7.47 (t, J = 7.8 Hz,2H), 7.26–7.23 (d, J = 10.4 Hz, 1H), 6.79–6.78 (d, J = 7.2 Hz, 1H), 6.69–6.66 (d, J = 10.4 Hz, 1H). 13H NMR (100 MHz, CDCl3, ppm): δ 185.6, 155.4, 146.2, 134.7, 134.1, 134.0, 133.1, 131.4, 131.4, 130.5, 127.9, 127.1, 126.7, 126.2, 126.1, 125.7, 125.5, 124.0, 114.7. Anal. Calcd for C20H13NO: C, 84.78; H, 4.63; N, 4.94. Found: C, 84.95; H, 4.59; N, 4.82.(6) 5H-spiro[dibenzo[c,h]acridine-7,9′-fluorene]-5,6(14H)-dione (SFDBAOO, 3). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) and acetone as solvent to give 3 (0.085 g, 0.184 mmol) as a red solid with the yield of 9%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.23–9.21 (d, J = 8.0 Hz, 1H), 9.18–9.16 (d, J = 8.0 Hz, 1H), 8.19–8.17 (d, J = 8.0 Hz, 1H), 7.93–7.87 (m, 3H), 7.74–7.66 (m, 3H), 7.57–7.53 (m, 1H), 7.44–7.40 (m, 3H),7.21–7.17 (t, J = 7.6 Hz, 2H), 7.11–7.09 (d, J = 7.6 Hz, 2H), 7.03 (s, 1H), 6.40–6.38 (d, J = 8.4 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 179.4, 150.6, 149.7, 149.5, 142.0, 137.4, 136.2, 133.6, 133.3, 132.0, 130.4, 129.6, 128.8, 128.3, 128.0, 127.6, 127.6, 127.0, 126.6, 126.1, 126.0, 124.8, 124.5, 123.8, 119.9, 116.1, 54.9. MALDI-TOF-MS calcd for C33H19NO2: 461.49 [M+], Found: 462.14.


#### 2.2.2. Syntheses of 2-(Thiophen-2-yl)-spiro [Fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (TSFDBAO)

A mixture of2c (0.523 g, 1.0 mmol), 2-thiopheneboronic acid 4 (0.154 g, 1.2 mmol), Pd(PPh3)4 (122 mg, 0.10 mmol), K2CO3 (2.0 M aqueous solution, 3.5 mL), and toluene (5 mL)/THF (5 mL) was stirred at 90°C under nitrogen atmosphere for 24 h. After it was cooled to room temperature, 200 mL of CH2Cl2 was added to the reaction mixture. The organic portion was separated and washed with brine before dried over anhydrous MgSO4. The solvent was evaporated off, and the solid residues were purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to afford TSFDBAO (0.437 g, 0.83 mmol) as red solids with the yield of 83%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.29–9.27 (d, J = 8.4 Hz, 1H), 9.08 9.05 (d, J = 8.4 Hz, 1H), 8.14–8.12 (d, J = 8.4 Hz, 1H), 7.87–7.83 (m, 3H), 7.78–7.75 (t, J = 8.0 Hz, 2H), 7.71–7.69 (d, J = 7.2 Hz, 1H), 7.69 7.66 (t, J = 8.4 Hz, 1H), 7.61–7.57 (t, J = 8.4 Hz, 1H), 7.57–7.55 (d, J = 8.4 Hz, 1H), 7.43–7.39 (t, J = 8.0 Hz, 1H), 7.25 (s, 1H), 7.19–7.17 (d, J = 7.6 Hz, 1H), 7.17–7.15 (m, 2H), 7.00–6.98 (d, J = 7.6 Hz, 1H), 6.97–6.95 (m, 1H), 6.62–6.60 (d, J = 8.4 Hz, 1H), 6.09 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.5, 152.5, 152.2, 149.9, 145.0, 143.6, 140.3, 140.0, 137.8, 135.6, 135.2, 133.7, 132.8, 132.2, 131.4, 130.8, 130.5, 130.4, 128.9, 128.7, 128.5, 128.0, 127.8, 127.3, 126.8, 126.7, 126.0, 125.3, 125.1, 124.7, 124.7, 123.8, 123.5, 122.2, 121.1, 120.7, 57.7. Anal. Calcd for C37H21NOS: C, 84.30; H, 4.02; N, 2.66. Found: C, 84.32; H, 4.01; N, 2.68.


#### 2.2.3. Syntheses of 2,7-Di(thiophen-2-yl)-spiro [Fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (DTSFDBAO)

A mixture of2d (0.60 g, 1.0 mmol), 2-thiopheneboronic acid 4 (0.282 g, 3.0 mmol), Pd(PPh3)4 (245 mL, 0.20 mmol), K2CO3 (2.0 M aqueous solution, 7.2 mL), and toluene (5 mL)/THF (5 mL) was stirred at 90°C under nitrogen atmosphere for 24 h. After it was cooled to room temperature, 200 mL of CH2Cl2 was added to the reaction mixture. The organic portion was separated and washed with brine before dried over anhydrous MgSO4. The solvent was evaporated off, and the solid residues were purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to afford DTSFDBAO (0.487 g, 0.80 mmol) as red solids with the yield of 80%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.31–9.29 (d, J = 8.4 Hz, 1H), 9.09–9.07 (d, J = 8.4 Hz, 1H), 8.14–8.12 (d, J = 7.6 Hz, 1H), 7.90–7.84 (m, 3H), 7.80–7.60 (t, J = 8.0 Hz, 2H), 7.70–7.67 (m, 3H), 7.62–7.56 (m, 2H), 7.20–7.20 (d, J = 1.6 Hz, 2H), 7.19–7.18 (d, J = 5.2 Hz, 2H), 7.16–7.15 (d, J = 3.6 Hz, 2H), 6.97–6.94 (m, 2H), 6.66–6.64 (d, J = 8.4 Hz, 1H), 6.13 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.5, 153.1, 149.9, 144.7, 143.6, 139.5, 137.7, 135.5, 135.2, 133.7, 132.8, 132.2, 131.4, 130.9, 130.9, 130.5, 128.1, 128.0, 127.8, 127.3, 126.9, 126.7, 126.0, 125.4, 125.1, 124.8, 123.8, 123.6, 122.0, 121.1, 57.5. Anal. Calcd for C41H23NOS2: C, 80.84; H, 3.81; N, 2.30. Found: C, 80.86; H, 3.82; N, 2.28.


## 2.1. Reagents and Instruments

All the reagents used were of analytical pure. The UV lamp irradiation is carried out indoors by a household 23 W compact fluorescent light (CFL) bulb.1H and 13C NMR spectra were performed on a Bruker 400 MHz spectrometer in CDCl3 or DMSO-d6 with tetramethylsilane (TMS) as the interval standard. Mass spectra were recorded on a Shimadzu GCMS-QP2010 plus equipped with DB-5 ms column or a Shimadzu AXIMA-CFR plus spectrometer. For the MALDI-TOF MS spectra, the spectra were recorded in reflective mode, and substrates were used. Molecular weights of the samples were measured by gel permeation chromatography (GPC) on a Shimadzu LC-20A HPLC system equipped with 7911GP-502 and GPNXC columns. Elemental analyses were carried out in an Elementar Analysensysteme GmbH-vario EL III element analyzer. Absorption spectra were measured with a Shimadzu UV-3600 spectrometer at 25°C, and emission spectra were recorded on a Shimadzu RF-5301(PC)S luminescence spectrometer. Cyclic voltammetric (CV) studies were conducted using a CHI660C electrochemical workstation in a typical three-electrode cell with a platinum sheet working electrode, a platinum wire counter electrode, and a silver/silver nitrate (Ag/Ag+) reference electrode. X-ray crystallographic data were collected at 293 K on a P4 Bruker diffractometer equipped with a fine-focus sealed tube and a rotating anode utilizing graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Data processing was carried out using the program SAINT, while the program SADABS was utilized for the scaling of diffraction data, the application of a decay correction, and an empirical absorption correction based on redundant reflections. The structures were solved by direct methods and refined against F2 with the full-matrix, least-squares methods using SHELXS-97 and SHELXL-97, respectively. Column chromatography purification was carried out using the silica gel (200–300 mesh).


## 2.2. Syntheses of the Intermediates and the Target Compounds

### 2.2.1. General Procedure for Preparation of2 and 3

In a round bottom flask, compound1 (2 mmol) was dissolved in MeCN (400 mL) and the mixture was stirred in the sunlight irradiation under air atmosphere for 6 hours to produce compound 2. The crude product was purified by flash column chromatography (silica gel, CH2Cl2/petroleum ether, 1: 3) to give purified products.(1) Spiro[fluorene-9,7′-dibenzo[c,h]acridi-ne]-5′-one (SFDBAO, 2a). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) to give 2a (0.69 g, 1.56 mmol) as a red solid with the yield of 78%. GC-MS (EI-m/z) calcd for C33H19NO+ [M]+ 445.15, found 445.00. 1H NMR (400 MHz, CDCl3, ppm): δ 9.28–9.26 (d, J = 8.4 Hz, 1H), 9.06–9.04 (d, J = 8.8 Hz, 1H), 8.14–8.12 (d, J = 8.8 Hz, 1H), 7.87–7.84 (m, 3H), 7.76–7.73 (t, J = 9.2 Hz, 2H), 7.68–7.64 (t, J = 8.4 Hz, 1H), 7.61–7.57 (t, J = 7.6 Hz, 1H), 7.55–7.53 (d, J = 8.4 Hz, 1H), 7.45–7.41 (t, J = 7.6 Hz, 2H), 7.22–7.18 (t, J = 7.6 Hz, 2H), 7.04–7.02 (d, J = 7.6 Hz, 2H), 6.57–6.55 (d, J = 8.8 Hz, 1H), 6.04 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 184.5, 151.7, 150.0, 145.4, 140.8, 137.8, 135.6, 133.6, 132.7, 132.2, 131.4, 130.8, 130.3, 128.9, 128.8, 128.6, 127.7, 127.2, 126.7, 125.9, 125.3, 124.8, 124.6, 123.8, 120.7, 57.7. Anal. Calcd for C33H19NO: C, 89.04; H, 4.30; N, 3.15. Found: C, 89.07; H, 4.28; N, 3.18.(2) 9′-Chlorospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (ClSFDBAO, 2b). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) and CCl4 (400 mL). Purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to give 2b (0.785 g, 1.64 mmol) as a red solid with the yield of 82%. GC-MS (EI-m/z) calcd for C33H18ClNO+ [M]+ 479.11, found 479.05. 1H NMR (400 MHz, CDCl3, ppm): δ 9.32–9.29 (d, J = 7.6 Hz, 1H), 9.02–9.00 (d, J = 8.0 Hz, 1H), 8.21–8.19 (d, J = 8.4 Hz, 1H), 8.13–8.11 (d, J = 7.6 Hz, 1H), 7.88–7.86 (d, J = 7.6 Hz, 3H), 7.84–7.79 (m, 1H), 7.72–7.66 (m, 2H), 7.47–7.43 (t, J = 7.4 Hz, 2H), 7.24–7.20 (t, J = 7.4 Hz, 2H), 7.04–7.02 (d, J = 7.6 Hz, 2H), 6.64 (s, 1H), 6.02 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): 13C NMR (100 MHz, CDCl3): δ 184.4, 151.1, 150.3, 145.0, 140.7, 137.0, 135.4, 133.8, 133.2, 132.8, 131.4, 130.9, 130.9, 130.4, 129.2, 129.0, 128.9, 127.9, 127.7, 126.0, 125.3, 124.8, 124.4, 124.2, 120.9, 57.5. Anal. Calcd for C33H18ClNO: C, 82.73; H, 3.79; N, 2.92. Found: C, 82.76; H, 3.77; N, 2.90.(3) 2-Bromospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (BrSFDBAO, 2c). This compound was prepared following the general procedures by applying 1c (1.02 g, 2 mmol) to give 2c (0.765 g, 1.46 mmol) as a red solid with the yield of 73%. GC-MS (EI-m/z) calcd for C33H18BrNO+ [M]+ 523.06, found 522.85. 1H NMR (400 MHz, CDCl3, ppm): δ 9.27–9.25 (d, J = 8.4 Hz, 1H), 9.05–9.03 (d, J = 7.6 Hz, 1H), 8.14–8.12 (d, J = 8.4 Hz, 1H), 7.89–7.95 (t, J = 7.6 Hz, 1H), 7.84–7.82 (d, J = 7.6 Hz, 1H), 7.80–7.75 (m, 2H), 7.75–7.67 (m, 2H), 7.62–7.54 (m, 3H), 7.46–7.42 (t, J = 7.6 Hz, 1H), 7.25–7.21 (t, J = 7.4 Hz, 1H), 7.14 (s, 1H), 7.03–7.01 (d, J = 7.6 Hz, 1H), 6.55–6.53 (d, J = 8.4 Hz, 1H), 6.02 (s, 1H). 13C NMR (101 MHz, CDCl3): δ 184.4, 153.5, 151.5, 149.9, 144.4, 139.7, 139.7, 137.8, 135.5, 133.7, 132.9, 132.2, 131.9, 131.3, 130.9, 130.5, 130., 129.4, 128.9, 128.0, 127.8, 127.7, 127.4, 126.9, 126.0, 125.4, 124.9, 124.4, 123.8, 122.2, 122.1, 120.7, 57.5. Anal. Calcd for C33H18BrNO: C, 75.78; H, 3.47; N, 2.68. Found: C, 75.81; H, 3.45; N, 2.66.(4) 2,7-Dibromospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (DBrSFDBAO, 2d). This compound was prepared following the general procedures by applying 1d (1.18 g, 2 mmol) to give 2d (0.844 g, 1.40 mmol) a red solid with the yield of 70%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.26–9.24 (d, J = 8.4 Hz, 1H), 9.05–9.03 (d, J = 7.6 Hz, 1H), 8.15–8.13 (d, J = 8.8 Hz, 1H), 7.90–7.86 (t, J = 7.6 Hz, 1H), 7.79–7.76 (m, 2H), 7.70–7.68 (d, J = 8.4 Hz, 3H), 7.64–7.58 (m, 2H), 7.57–7.55 (dd, J = 8.2, 1.8 Hz, 2H), 7.14–7.14 (d, J = 1.6 Hz, 2H), 6.53–6.51 (d, J = 8.8 Hz, 1H), 6.01 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.3, 153.4, 149.7, 143.4, 138.6, 137.7, 135.3, 133.8, 133.0, 132.2, 132.1, 131.3, 131.0, 130.8, 130.6, 128.1, 127.8, 127.5, 127.1, 126.5, 126.0, 125.5, 124.2, 123.9, 122.8, 122.1, 57.3. Anal. Calcd for C33H17Br2NO: C, 65.95; H, 2.85; N, 2.33. Found: C, 65.92; H, 2.86; N, 2.35.(5) (Z)-4-(Naphthalen-1-ylimino)naphthalen-1(4H)-one (NINO, 2e). This compound was prepared following the general procedures by applying 1e (0.538 g, 2 mmol) to give 2e (0.463 g, 1.64 mmol) as a red solid with the yield of 82%. GC-MS (EI-m/z) calcd for C20H13NO+ [M]+ 283.10, found 282.95. 1H NMR (400 MHz, CDCl3, ppm): δ 8.68–8.66 (d, J = 8.4 Hz, 1H), 8.23–8.21 (d, J = 7.6 Hz, 1H), 7.91–7.88 (d, J = 8.8 Hz, 2H), 7.83–7.79 (t, J = 7.6 Hz, 1H), 7.75–7.73 (d, J = 8.0 Hz, 2H), 7.57–7.53 (t, J = 7.6 Hz, 1H), 7.51–7.47 (t, J = 7.8 Hz,2H), 7.26–7.23 (d, J = 10.4 Hz, 1H), 6.79–6.78 (d, J = 7.2 Hz, 1H), 6.69–6.66 (d, J = 10.4 Hz, 1H). 13H NMR (100 MHz, CDCl3, ppm): δ 185.6, 155.4, 146.2, 134.7, 134.1, 134.0, 133.1, 131.4, 131.4, 130.5, 127.9, 127.1, 126.7, 126.2, 126.1, 125.7, 125.5, 124.0, 114.7. Anal. Calcd for C20H13NO: C, 84.78; H, 4.63; N, 4.94. Found: C, 84.95; H, 4.59; N, 4.82.(6) 5H-spiro[dibenzo[c,h]acridine-7,9′-fluorene]-5,6(14H)-dione (SFDBAOO, 3). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) and acetone as solvent to give 3 (0.085 g, 0.184 mmol) as a red solid with the yield of 9%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.23–9.21 (d, J = 8.0 Hz, 1H), 9.18–9.16 (d, J = 8.0 Hz, 1H), 8.19–8.17 (d, J = 8.0 Hz, 1H), 7.93–7.87 (m, 3H), 7.74–7.66 (m, 3H), 7.57–7.53 (m, 1H), 7.44–7.40 (m, 3H),7.21–7.17 (t, J = 7.6 Hz, 2H), 7.11–7.09 (d, J = 7.6 Hz, 2H), 7.03 (s, 1H), 6.40–6.38 (d, J = 8.4 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 179.4, 150.6, 149.7, 149.5, 142.0, 137.4, 136.2, 133.6, 133.3, 132.0, 130.4, 129.6, 128.8, 128.3, 128.0, 127.6, 127.6, 127.0, 126.6, 126.1, 126.0, 124.8, 124.5, 123.8, 119.9, 116.1, 54.9. MALDI-TOF-MS calcd for C33H19NO2: 461.49 [M+], Found: 462.14.


### 2.2.2. Syntheses of 2-(Thiophen-2-yl)-spiro [Fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (TSFDBAO)

A mixture of2c (0.523 g, 1.0 mmol), 2-thiopheneboronic acid 4 (0.154 g, 1.2 mmol), Pd(PPh3)4 (122 mg, 0.10 mmol), K2CO3 (2.0 M aqueous solution, 3.5 mL), and toluene (5 mL)/THF (5 mL) was stirred at 90°C under nitrogen atmosphere for 24 h. After it was cooled to room temperature, 200 mL of CH2Cl2 was added to the reaction mixture. The organic portion was separated and washed with brine before dried over anhydrous MgSO4. The solvent was evaporated off, and the solid residues were purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to afford TSFDBAO (0.437 g, 0.83 mmol) as red solids with the yield of 83%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.29–9.27 (d, J = 8.4 Hz, 1H), 9.08 9.05 (d, J = 8.4 Hz, 1H), 8.14–8.12 (d, J = 8.4 Hz, 1H), 7.87–7.83 (m, 3H), 7.78–7.75 (t, J = 8.0 Hz, 2H), 7.71–7.69 (d, J = 7.2 Hz, 1H), 7.69 7.66 (t, J = 8.4 Hz, 1H), 7.61–7.57 (t, J = 8.4 Hz, 1H), 7.57–7.55 (d, J = 8.4 Hz, 1H), 7.43–7.39 (t, J = 8.0 Hz, 1H), 7.25 (s, 1H), 7.19–7.17 (d, J = 7.6 Hz, 1H), 7.17–7.15 (m, 2H), 7.00–6.98 (d, J = 7.6 Hz, 1H), 6.97–6.95 (m, 1H), 6.62–6.60 (d, J = 8.4 Hz, 1H), 6.09 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.5, 152.5, 152.2, 149.9, 145.0, 143.6, 140.3, 140.0, 137.8, 135.6, 135.2, 133.7, 132.8, 132.2, 131.4, 130.8, 130.5, 130.4, 128.9, 128.7, 128.5, 128.0, 127.8, 127.3, 126.8, 126.7, 126.0, 125.3, 125.1, 124.7, 124.7, 123.8, 123.5, 122.2, 121.1, 120.7, 57.7. Anal. Calcd for C37H21NOS: C, 84.30; H, 4.02; N, 2.66. Found: C, 84.32; H, 4.01; N, 2.68.


### 2.2.3. Syntheses of 2,7-Di(thiophen-2-yl)-spiro [Fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (DTSFDBAO)

A mixture of2d (0.60 g, 1.0 mmol), 2-thiopheneboronic acid 4 (0.282 g, 3.0 mmol), Pd(PPh3)4 (245 mL, 0.20 mmol), K2CO3 (2.0 M aqueous solution, 7.2 mL), and toluene (5 mL)/THF (5 mL) was stirred at 90°C under nitrogen atmosphere for 24 h. After it was cooled to room temperature, 200 mL of CH2Cl2 was added to the reaction mixture. The organic portion was separated and washed with brine before dried over anhydrous MgSO4. The solvent was evaporated off, and the solid residues were purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to afford DTSFDBAO (0.487 g, 0.80 mmol) as red solids with the yield of 80%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.31–9.29 (d, J = 8.4 Hz, 1H), 9.09–9.07 (d, J = 8.4 Hz, 1H), 8.14–8.12 (d, J = 7.6 Hz, 1H), 7.90–7.84 (m, 3H), 7.80–7.60 (t, J = 8.0 Hz, 2H), 7.70–7.67 (m, 3H), 7.62–7.56 (m, 2H), 7.20–7.20 (d, J = 1.6 Hz, 2H), 7.19–7.18 (d, J = 5.2 Hz, 2H), 7.16–7.15 (d, J = 3.6 Hz, 2H), 6.97–6.94 (m, 2H), 6.66–6.64 (d, J = 8.4 Hz, 1H), 6.13 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.5, 153.1, 149.9, 144.7, 143.6, 139.5, 137.7, 135.5, 135.2, 133.7, 132.8, 132.2, 131.4, 130.9, 130.9, 130.5, 128.1, 128.0, 127.8, 127.3, 126.9, 126.7, 126.0, 125.4, 125.1, 124.8, 123.8, 123.6, 122.0, 121.1, 57.5. Anal. Calcd for C41H23NOS2: C, 80.84; H, 3.81; N, 2.30. Found: C, 80.86; H, 3.82; N, 2.28.


## 2.2.1. General Procedure for Preparation of2 and 3

In a round bottom flask, compound1 (2 mmol) was dissolved in MeCN (400 mL) and the mixture was stirred in the sunlight irradiation under air atmosphere for 6 hours to produce compound 2. The crude product was purified by flash column chromatography (silica gel, CH2Cl2/petroleum ether, 1: 3) to give purified products.(1) Spiro[fluorene-9,7′-dibenzo[c,h]acridi-ne]-5′-one (SFDBAO, 2a). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) to give 2a (0.69 g, 1.56 mmol) as a red solid with the yield of 78%. GC-MS (EI-m/z) calcd for C33H19NO+ [M]+ 445.15, found 445.00. 1H NMR (400 MHz, CDCl3, ppm): δ 9.28–9.26 (d, J = 8.4 Hz, 1H), 9.06–9.04 (d, J = 8.8 Hz, 1H), 8.14–8.12 (d, J = 8.8 Hz, 1H), 7.87–7.84 (m, 3H), 7.76–7.73 (t, J = 9.2 Hz, 2H), 7.68–7.64 (t, J = 8.4 Hz, 1H), 7.61–7.57 (t, J = 7.6 Hz, 1H), 7.55–7.53 (d, J = 8.4 Hz, 1H), 7.45–7.41 (t, J = 7.6 Hz, 2H), 7.22–7.18 (t, J = 7.6 Hz, 2H), 7.04–7.02 (d, J = 7.6 Hz, 2H), 6.57–6.55 (d, J = 8.8 Hz, 1H), 6.04 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 184.5, 151.7, 150.0, 145.4, 140.8, 137.8, 135.6, 133.6, 132.7, 132.2, 131.4, 130.8, 130.3, 128.9, 128.8, 128.6, 127.7, 127.2, 126.7, 125.9, 125.3, 124.8, 124.6, 123.8, 120.7, 57.7. Anal. Calcd for C33H19NO: C, 89.04; H, 4.30; N, 3.15. Found: C, 89.07; H, 4.28; N, 3.18.(2) 9′-Chlorospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (ClSFDBAO, 2b). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) and CCl4 (400 mL). Purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to give 2b (0.785 g, 1.64 mmol) as a red solid with the yield of 82%. GC-MS (EI-m/z) calcd for C33H18ClNO+ [M]+ 479.11, found 479.05. 1H NMR (400 MHz, CDCl3, ppm): δ 9.32–9.29 (d, J = 7.6 Hz, 1H), 9.02–9.00 (d, J = 8.0 Hz, 1H), 8.21–8.19 (d, J = 8.4 Hz, 1H), 8.13–8.11 (d, J = 7.6 Hz, 1H), 7.88–7.86 (d, J = 7.6 Hz, 3H), 7.84–7.79 (m, 1H), 7.72–7.66 (m, 2H), 7.47–7.43 (t, J = 7.4 Hz, 2H), 7.24–7.20 (t, J = 7.4 Hz, 2H), 7.04–7.02 (d, J = 7.6 Hz, 2H), 6.64 (s, 1H), 6.02 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): 13C NMR (100 MHz, CDCl3): δ 184.4, 151.1, 150.3, 145.0, 140.7, 137.0, 135.4, 133.8, 133.2, 132.8, 131.4, 130.9, 130.9, 130.4, 129.2, 129.0, 128.9, 127.9, 127.7, 126.0, 125.3, 124.8, 124.4, 124.2, 120.9, 57.5. Anal. Calcd for C33H18ClNO: C, 82.73; H, 3.79; N, 2.92. Found: C, 82.76; H, 3.77; N, 2.90.(3) 2-Bromospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (BrSFDBAO, 2c). This compound was prepared following the general procedures by applying 1c (1.02 g, 2 mmol) to give 2c (0.765 g, 1.46 mmol) as a red solid with the yield of 73%. GC-MS (EI-m/z) calcd for C33H18BrNO+ [M]+ 523.06, found 522.85. 1H NMR (400 MHz, CDCl3, ppm): δ 9.27–9.25 (d, J = 8.4 Hz, 1H), 9.05–9.03 (d, J = 7.6 Hz, 1H), 8.14–8.12 (d, J = 8.4 Hz, 1H), 7.89–7.95 (t, J = 7.6 Hz, 1H), 7.84–7.82 (d, J = 7.6 Hz, 1H), 7.80–7.75 (m, 2H), 7.75–7.67 (m, 2H), 7.62–7.54 (m, 3H), 7.46–7.42 (t, J = 7.6 Hz, 1H), 7.25–7.21 (t, J = 7.4 Hz, 1H), 7.14 (s, 1H), 7.03–7.01 (d, J = 7.6 Hz, 1H), 6.55–6.53 (d, J = 8.4 Hz, 1H), 6.02 (s, 1H). 13C NMR (101 MHz, CDCl3): δ 184.4, 153.5, 151.5, 149.9, 144.4, 139.7, 139.7, 137.8, 135.5, 133.7, 132.9, 132.2, 131.9, 131.3, 130.9, 130.5, 130., 129.4, 128.9, 128.0, 127.8, 127.7, 127.4, 126.9, 126.0, 125.4, 124.9, 124.4, 123.8, 122.2, 122.1, 120.7, 57.5. Anal. Calcd for C33H18BrNO: C, 75.78; H, 3.47; N, 2.68. Found: C, 75.81; H, 3.45; N, 2.66.(4) 2,7-Dibromospiro[fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (DBrSFDBAO, 2d). This compound was prepared following the general procedures by applying 1d (1.18 g, 2 mmol) to give 2d (0.844 g, 1.40 mmol) a red solid with the yield of 70%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.26–9.24 (d, J = 8.4 Hz, 1H), 9.05–9.03 (d, J = 7.6 Hz, 1H), 8.15–8.13 (d, J = 8.8 Hz, 1H), 7.90–7.86 (t, J = 7.6 Hz, 1H), 7.79–7.76 (m, 2H), 7.70–7.68 (d, J = 8.4 Hz, 3H), 7.64–7.58 (m, 2H), 7.57–7.55 (dd, J = 8.2, 1.8 Hz, 2H), 7.14–7.14 (d, J = 1.6 Hz, 2H), 6.53–6.51 (d, J = 8.8 Hz, 1H), 6.01 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.3, 153.4, 149.7, 143.4, 138.6, 137.7, 135.3, 133.8, 133.0, 132.2, 132.1, 131.3, 131.0, 130.8, 130.6, 128.1, 127.8, 127.5, 127.1, 126.5, 126.0, 125.5, 124.2, 123.9, 122.8, 122.1, 57.3. Anal. Calcd for C33H17Br2NO: C, 65.95; H, 2.85; N, 2.33. Found: C, 65.92; H, 2.86; N, 2.35.(5) (Z)-4-(Naphthalen-1-ylimino)naphthalen-1(4H)-one (NINO, 2e). This compound was prepared following the general procedures by applying 1e (0.538 g, 2 mmol) to give 2e (0.463 g, 1.64 mmol) as a red solid with the yield of 82%. GC-MS (EI-m/z) calcd for C20H13NO+ [M]+ 283.10, found 282.95. 1H NMR (400 MHz, CDCl3, ppm): δ 8.68–8.66 (d, J = 8.4 Hz, 1H), 8.23–8.21 (d, J = 7.6 Hz, 1H), 7.91–7.88 (d, J = 8.8 Hz, 2H), 7.83–7.79 (t, J = 7.6 Hz, 1H), 7.75–7.73 (d, J = 8.0 Hz, 2H), 7.57–7.53 (t, J = 7.6 Hz, 1H), 7.51–7.47 (t, J = 7.8 Hz,2H), 7.26–7.23 (d, J = 10.4 Hz, 1H), 6.79–6.78 (d, J = 7.2 Hz, 1H), 6.69–6.66 (d, J = 10.4 Hz, 1H). 13H NMR (100 MHz, CDCl3, ppm): δ 185.6, 155.4, 146.2, 134.7, 134.1, 134.0, 133.1, 131.4, 131.4, 130.5, 127.9, 127.1, 126.7, 126.2, 126.1, 125.7, 125.5, 124.0, 114.7. Anal. Calcd for C20H13NO: C, 84.78; H, 4.63; N, 4.94. Found: C, 84.95; H, 4.59; N, 4.82.(6) 5H-spiro[dibenzo[c,h]acridine-7,9′-fluorene]-5,6(14H)-dione (SFDBAOO, 3). This compound was prepared following the general procedures by applying 1a (0.862 g, 2 mmol) and acetone as solvent to give 3 (0.085 g, 0.184 mmol) as a red solid with the yield of 9%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.23–9.21 (d, J = 8.0 Hz, 1H), 9.18–9.16 (d, J = 8.0 Hz, 1H), 8.19–8.17 (d, J = 8.0 Hz, 1H), 7.93–7.87 (m, 3H), 7.74–7.66 (m, 3H), 7.57–7.53 (m, 1H), 7.44–7.40 (m, 3H),7.21–7.17 (t, J = 7.6 Hz, 2H), 7.11–7.09 (d, J = 7.6 Hz, 2H), 7.03 (s, 1H), 6.40–6.38 (d, J = 8.4 Hz, 1H). 13C NMR (100 MHz, CDCl3) δ 179.4, 150.6, 149.7, 149.5, 142.0, 137.4, 136.2, 133.6, 133.3, 132.0, 130.4, 129.6, 128.8, 128.3, 128.0, 127.6, 127.6, 127.0, 126.6, 126.1, 126.0, 124.8, 124.5, 123.8, 119.9, 116.1, 54.9. MALDI-TOF-MS calcd for C33H19NO2: 461.49 [M+], Found: 462.14.


## 2.2.2. Syntheses of 2-(Thiophen-2-yl)-spiro [Fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (TSFDBAO)

A mixture of2c (0.523 g, 1.0 mmol), 2-thiopheneboronic acid 4 (0.154 g, 1.2 mmol), Pd(PPh3)4 (122 mg, 0.10 mmol), K2CO3 (2.0 M aqueous solution, 3.5 mL), and toluene (5 mL)/THF (5 mL) was stirred at 90°C under nitrogen atmosphere for 24 h. After it was cooled to room temperature, 200 mL of CH2Cl2 was added to the reaction mixture. The organic portion was separated and washed with brine before dried over anhydrous MgSO4. The solvent was evaporated off, and the solid residues were purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to afford TSFDBAO (0.437 g, 0.83 mmol) as red solids with the yield of 83%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.29–9.27 (d, J = 8.4 Hz, 1H), 9.08 9.05 (d, J = 8.4 Hz, 1H), 8.14–8.12 (d, J = 8.4 Hz, 1H), 7.87–7.83 (m, 3H), 7.78–7.75 (t, J = 8.0 Hz, 2H), 7.71–7.69 (d, J = 7.2 Hz, 1H), 7.69 7.66 (t, J = 8.4 Hz, 1H), 7.61–7.57 (t, J = 8.4 Hz, 1H), 7.57–7.55 (d, J = 8.4 Hz, 1H), 7.43–7.39 (t, J = 8.0 Hz, 1H), 7.25 (s, 1H), 7.19–7.17 (d, J = 7.6 Hz, 1H), 7.17–7.15 (m, 2H), 7.00–6.98 (d, J = 7.6 Hz, 1H), 6.97–6.95 (m, 1H), 6.62–6.60 (d, J = 8.4 Hz, 1H), 6.09 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.5, 152.5, 152.2, 149.9, 145.0, 143.6, 140.3, 140.0, 137.8, 135.6, 135.2, 133.7, 132.8, 132.2, 131.4, 130.8, 130.5, 130.4, 128.9, 128.7, 128.5, 128.0, 127.8, 127.3, 126.8, 126.7, 126.0, 125.3, 125.1, 124.7, 124.7, 123.8, 123.5, 122.2, 121.1, 120.7, 57.7. Anal. Calcd for C37H21NOS: C, 84.30; H, 4.02; N, 2.66. Found: C, 84.32; H, 4.01; N, 2.68.


## 2.2.3. Syntheses of 2,7-Di(thiophen-2-yl)-spiro [Fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (DTSFDBAO)

A mixture of2d (0.60 g, 1.0 mmol), 2-thiopheneboronic acid 4 (0.282 g, 3.0 mmol), Pd(PPh3)4 (245 mL, 0.20 mmol), K2CO3 (2.0 M aqueous solution, 7.2 mL), and toluene (5 mL)/THF (5 mL) was stirred at 90°C under nitrogen atmosphere for 24 h. After it was cooled to room temperature, 200 mL of CH2Cl2 was added to the reaction mixture. The organic portion was separated and washed with brine before dried over anhydrous MgSO4. The solvent was evaporated off, and the solid residues were purified by flash column chromatography using CH2Cl2 : petroleum ether = 1 : 3 to afford DTSFDBAO (0.487 g, 0.80 mmol) as red solids with the yield of 80%. 1H NMR (400 MHz, CDCl3, ppm): δ 9.31–9.29 (d, J = 8.4 Hz, 1H), 9.09–9.07 (d, J = 8.4 Hz, 1H), 8.14–8.12 (d, J = 7.6 Hz, 1H), 7.90–7.84 (m, 3H), 7.80–7.60 (t, J = 8.0 Hz, 2H), 7.70–7.67 (m, 3H), 7.62–7.56 (m, 2H), 7.20–7.20 (d, J = 1.6 Hz, 2H), 7.19–7.18 (d, J = 5.2 Hz, 2H), 7.16–7.15 (d, J = 3.6 Hz, 2H), 6.97–6.94 (m, 2H), 6.66–6.64 (d, J = 8.4 Hz, 1H), 6.13 (s, 1H). 13C NMR (100 MHz, CDCl3, ppm): δ 184.5, 153.1, 149.9, 144.7, 143.6, 139.5, 137.7, 135.5, 135.2, 133.7, 132.8, 132.2, 131.4, 130.9, 130.9, 130.5, 128.1, 128.0, 127.8, 127.3, 126.9, 126.7, 126.0, 125.4, 125.1, 124.8, 123.8, 123.6, 122.0, 121.1, 57.5. Anal. Calcd for C41H23NOS2: C, 80.84; H, 3.81; N, 2.30. Found: C, 80.86; H, 3.82; N, 2.28.


## 3. Results and Discussion

Initially, our explorations toward an photooxygenation protocol under mild reaction conditions focused on the reaction of 14H-spiro- [dibenzo[c,h]acridine-7,9′-fluorene] (SFDBA,1a) (Table 1). First, the reaction of 1a was purposively carried out in CCl4 by exposure to UV irradiation of 365 nm for 24 h, giving the chloro-substituted oxidative product (ClSFDBAO) 2b in 40% yield, whereas the SFDBAO product 2a was not observed (entry 1). The structure of 2b was confirmed unambiguously by X-ray single-crystal diffraction (Figure 2). It is exciting that the conversion yield of 2b was improved up to 82% by exposure to sunlight at room temperature in CCl4 (entry 2). A possible mechanism for the formation of ClSFDBAO (2b) is depicted in Figure S6 (see Supplementary Materials). When acetone was used as the solvent and conducted at room temperature, the desired product (SFDBAO) 2a was obtained in 76% yield, and 9% of 5H-spiro[dibenzo[c,h] acridine-7,9′-fluorene]-5,6(14H)-dione (SFDBAOO) 3 as a by-product was detected (entry 3). The structure of 3 was confirmed unambiguously by X-ray single-crystal diffraction (Figure 2). Solvent screening indicates that MeCN was the most efficient. Other solvents such as, MeOH, THF, DMF, and toluene gave relatively low yields of 2a (entries 4–8). No target compound 2a was obtained in the dark when heating up more than 80°C (entry 9). Additionally, no product 2a was obtained in N2 atmosphere (entry 11), indicating oxygen in the atmosphere participated in the visible-light-mediated photooxygenation of 1a. This result was further supported by the control experiments using the purified O2 source to give 2a in 83% yield (entry 10). Moreover, a write-once, read-many (WORM) type memory device based on SFDBAO derivative nanosheets as electroactive layers shows an ON/OFF ratio of 6.0 × 104, accompanied by an interesting photoswitching behavior. The results presented have shown that SFDBAO derivatives are promising electroactive materials for the memory device application [22, 23]. Compared with our previous reports, further study of the conditions and the scope of this reaction were conducted in detail.Table 1
Optimization of the reaction conditionsa.
Entry
Solvent
Irradiation
Gas
Time (h)
Yield (%)b
1
CCl4
UV lampc
Air
24
40d
2
CCl4
Sunlight
Air
6
82d
3
Acetone
Sunlight
Air
6
76
4
MeOH
Sunlight
Air
6
30
5
THF
Sunlight
Air
6
10
6
DMF
Sunlight
Air
6
20
7
Toluene
Sunlight
Air
6
50
8
MeCN
Sunlight
Air
6
78
9e
MeCN
Dark
Air
6
nr
10
MeCN
Sunlight
O2
3
83
11
MeCN
Sunlight
N2
6
nr
aReactions were carried out with 1a (2.0 mmol) in solvent (400 mL) for 6 h. bIsolated yields. c365 nm. dWith isolated yield of 2b. eAt 80°C.Figure 2
Single-crystal X-ray structures of2b and 3 and the packing structure of 2b.
(a)
(b)
(c)Under the optimized conditions (Table1, entry 8), a range of reactions were performed with various substrates 1 (Scheme 2). The reactions of spirofluoreneacridines proceeded smoothly to afford the corresponding photooxygenation products 2(a–d) in good to excellent yields (70–82%). Then, di (naphthalen-1-yl)amine was compatible with this reaction, affording the desired product 2e in 82% yields. To our disappointment, no desired products were obtained when naphthylamine and anilines were employed in the present reaction system (see Supplementary Materials Figure S6).Scheme 2
Scope of the iminoquinones.aReactions were carried out with 1 (2.0 mmol) in MeCN (400 mL) for 6 h. bIsolated yields.Chemical structures of the SFDBAO derivatives were unambiguously confirmed by GC-MS,1H and 13C NMR, X-ray crystallography, and elementary analyses. The single-crystal X-ray diffraction structures of ClSFDBAO (2b) and SFDBAOO (3) are shown in Figure S3–S5 and Table S1. ClSFDBAO and SFDBAOO from a mixture of dichloromethane/alcohol and a mixture idines in ClSFDBAO are incompletely perpendicular with fluorene plane according to X-ray crystallography, obviously different from spirobifluorenes. ClSFDBAO exhibit well-defined consecutive intermolecular π-stacked motifs among adjacent dibenzoacridines with a close distance of 3.346 Å in the molecular packing graph (Figure 2), which is in the range of the distance of the typical π-π stacking interactions relative to range over 3.4–3.8 Å. The closely interplanar distances are favorable for the electron delocalization and the improvement of mobility in organic films and devices.To clarify the SFDBA and SFDBAO together as a photosensitive catalyst involved in the reaction leading to SFDBAO, control experiments were performed (Figure3). The optical absorption properties of the SFDBA and SFDBAO were investigated by UV-vis absorption spectra as shown in Figure 3. The absorption spectra in dilute CHCl3 of SFDBA and SFDBAO show absorption at 370 nm and 470 nm, respectively. Therefore, we tested the absorption spectra of SFDBA 1a at different reaction times under the sunlight, the 365 nm UV lamp, and the 490 nm UV lamp, respectively. As a result, we found that the yield of SFDBAO increased gradually with the increase of reaction time under the sunlight and 490 nm UV lamp. However, the yield of SFDBAO increased very slowly with the increase of reaction time under the 365 nm UV lamp. The experimental results indicate that SFDBA acts as a photosensitive catalyst to induce the formation of SFDBAO in the initial reaction period, and then, SFDBAO also acts as another photosensitive catalyst accelerating the conversion together with SFDBA.Figure 3
(a) The absorption spectra of SFDBA and SFDBAO. Absorption spectra of1a at different reaction times: (b) under the sunlight, (c) under the 365 nm UV lamp, and (d) under 490 nm UV lamp.
(a)
(b)
(c)
(d)On the basis of all the results described above, a plausible and preliminary mechanism has been proposed, as depicted in Scheme3. In the self-sensitizations cycle, naphthylamines is converted to the excited singlet state under the sunlight irradiation. Subsequently, the excited triplet singlet state is formed through intramolecularly intersystem crossing (ISC) of the excited singlet state. The triplet energy of the naphthylamines can be transferred to the ground state oxygen molecule to produce singlet oxygen to close this catalytic cycle. After that, an electron transfer of singlet oxygen from 1 occurs, leading to the formation of radical cation species I/II. Then, a [4 + 2] cycloaddition is given to intermediate II, and the O–O bond cleavage of intermediate III led to intermediate IV, which was readily oxidized by dioxygen to produce the desired iminoquinones 2 [24–26].Scheme 3
The proposed triplet sensitization mechanism.In order to explore the photoelectric property ofn-type spiro-based organic semiconductors SFDBAO, we smoothly synthesized the thiophene-substituted SFDBAO D-A (p-n)-type organic semiconductors, which will become important monomers for low-bandgap π-conjugated polymers in solar cells (Scheme 4). The reactions of 2c and 2d with thiophen-2-ylboronic acid 4 under Pd(PPh3)4 catalytic conditions gave 2′-(thiophen-2-yl)- 5H-spiro[dibenzo[c,h]acridine-7,9′-fluoren]-5-one (TSFDBAO) and 2′,7′-di(thiophen-2-yl) -5H-spiro[dibenzo[c,h]acridine-7,9′-fluoren]-5-one (DTSFDBAO) in 83% and 80% yields, respectively.Scheme 4
Synthesis of the thiophene-substituted SFDBAO D-A (p-n)-type organic semiconductors.
(a)
(b)The optical and electrochemical properties of the SFDBAO, TSFDBAO, and DTSFDBAO were investigated by UV-vis absorption spectra, photoluminescence (PL) spectra, and cyclic voltammetry (CV), as shown in Figure4 and summarized in Table S2 (see Supplementary Materials). UV-vis spectra exhibit the maximum absorption peak at 470 nm for SFDBAO. SFDBAO with a red-yellow color about 565 nm. Thiophene-substituted SFDBAO exhibit the new electronic absorption bands at 322 nm for TSFDBAO and 353 nm for DTSFDBAO without the obvious change of PL peaks, expect for the reduced emission intensity probably owing to heavy atom effects of sulfur. The first turn-on oxidation potentials of SFDBAO occur at 0.98 V (vs Fe+/Fe) for SFDBAO, 0.96 V (vs Fe+/Fe) for TSFDBAO, and 0.71 V for DTSFDBAO, respectively. These results indicate that DTSFDBAO has better electron-donating properties owing to the introduction of the double thiophene groups. Furthermore, all the SFDBAO derivatives exhibit the reversible reduction processes with the similar onset first potential of around −1.00 V (vs Fe+/Fe). Their LUMO energy levels are estimated and determined from the onset of the reduction to be −3.73 eV for SFDBAO, −3.78 eV for TSFDBAO, and −3.77 eV for DTSFDBAO with regard to the energy level of ferrocene (4.8 eV below vacuum), respectively. The lower LUMO is probably assigned to the spiro-dibenzoacridine moieties with the electron-withdrawing properties, which are in the range of the LUMO energy level of acceptor material in solar cells [27, 28]. Their bandages are 2.02 eV for SFDBAO, 1.95 V for TSFDBAO, and 1.71 V for DTSFDBAO, respectively. These data suggest that the SFDBAOs are potential n-type green organic semiconductors.Figure 4
The photophysical and electrochemical properties of SFDBAO. (a) UV-vis electronic absorption spectra and photoluminescence spectra. (b) Reductive and oxidative cyclic voltammograms, 0.1 M n-Bu4NPF6 in THF (reduction) and 0.1 M n-Bu4NPF6 in CH2Cl2 (oxidation), were used as supporting electrolytes. A platinum sheet electrode was used as the working electrode; the scanning rate was 100 mV/s, where E+ (Fc/Fc) is about 0.03 V.
(a)
(b)


## 4. Conclusions

We have developed a green efficient access to iminoquinones from naphthylamines based on the photooxygenation and self-sensitizations, in which naphthylamines play a dual role of providing both photosensitizer and substrate, and O2 functions as triplet state trapping agent and oxygen source. Air atmosphere and sunlight irradiations are crucial conditions of the photooxygenation reaction to obtain the high-yield products. This sunlight-induced C-H activation gives a kind of new n-type spiro-based organic semiconductors. Further work on the application of SFDBAO-based materials is ongoing in our laboratory.



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*Source: 9180671-2018-05-20.xml*