Introduction

Multi-component reaction (MCRs) is a chemical reactions that three or more raw materials produce a single product in one step. The target molecules have great efficiency and reagents atom economy. MCRs are used for the efficient synthesis of natural compounds for the discovery of biological activities and drugs [1,2,3,4,5]. The importance of multi-component compounds in organic chemistry has been proven [6, 7]. The spiro compounds are an important class of naturally occurring material characterized by highly significant biological properties. 4H-pyrans derivatives have been considered because their pharmacological activity [8] that include anti-anaphylactic activity [9, 10], anticancer [11], cytotoxic [12], anti-HIV [13, 14], anti-inflammatory [15], antimalarial [16, 17], antimicrobial [18], antineurodegenerative disorders like Alzheimer’s, Parkinson’s, and Huntington’s disease and many more [19]. 4H-pyrans are useful intermediates for synthesis of pyranopyridine derivatives [20], polyazanaphthalenes [21], pyranopyrimidines, and pyridin-2-ones [22]. The 2-amino-3-cyano-4H-pyrans showed important photochemical activity [23]. Recently, a series of synthetic 2-amino-3-cyano-4H-pyrans (Fig. 1) have been appraised to possess potent anticancer, antibacterial, antifungal, and antirheumatic properties [24]. Pyrazolone structure is a well-known heterocycle in many drug materials of medicinal fields. Some pyrazolone derivatives (Fig. 2) such as antipyrine (phenazone), aminopyrine (aminophenazone), metamizol (novalgin), and 4-isopropylpyrine (propyphenazone) are all useful antipyretic and analgesic drugs [25]. Pyrazolone derivatives have applications in the development of acaricides, dyes, fungicides, herbicides, insecticides, inhibitors omnipresence, and reagents [26, 27]. Recently, several methods have been reported for the synthesis of a series of spiro-pyran derivatives [28]. However, some of the reported method such as way ammonium chloride (20 mol%) was found as catalyst for the multi-component reaction of acenaphthenequinone, 1,3-cyclohexanedione or dimedone, and malononitrile for the formation of spiroacenaphthylene-chromenes in 75–90% yields. Triethylamine (20 mol%) recently has been used to catalyst general multi-component reaction of acenaphthenequinone, containing carbonyl group CH-acids and malononitrile with the formation of spiroacenaphthylenes in 40–85% yields [29]. Our approach for the synthesis of spiroacenaphthylene without using catalyst in water under mild reaction conditions, and high yields are described.

Fig. 1
figure 1

Selected bioactive compounds consisted of 2-amino-4H-pyrans

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Fig. 2
figure 2

Typical compounds of bioactive pyrazolones

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Results and discussion

Initially, a three-component reaction between acenaphthoquinone 1, pyrazolone 2, and activated methylene reagent (malononitrile) 3 was used as a model to optimize the reaction conditions. That obtained 6′-amino-1′-(2-chlorophenyl)-3′-methyl-2-oxo-1′H,2H-spiro[acenaphthylene-1,4′-pyrano[2,3-c]pyrazole]-5′-carbonitrile 4a, in excellent yields (Scheme 1).

Scheme 1
scheme 1

Synthesis of spiroacenaphthelyne-pyranopyrazole via three-component reaction

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To achieve the optimal conditions for the synthesis of 4a, we examined the condensation reaction of acenaphthenequinone 1 (1 mmol), 1-(2-chlorophenyl)-3-methyl-1H-pyrazol-5(4H)-one 2a (1 mmol), and malononitrile (1 mmol), in several different solvents (water, EtOH, MeOH) and also in different temperatures (Table 1). The results clearly indicate that using H2O as a green solvent in 80 °C leads to an increase in the synthetic efficiency to 98%. Therefore, it shows superiority over the other conditions as reaction media (entry 5).

Table 1 Synthetic results of 4a under different solvent conditions
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Thus, under the optimized reaction conditions, we used various substituted 1-aryl pyrazolone derivatives such as 1-(chlorophenyl)-3-methyl pyrazolone and 1-methyl-3-(trifluoromethyl)pyrazolone with malononitrile, methyl cyanoacetate, and ethyl cyanoacetate gave the desired product 4a–4l with excellent yields (Table 2). The structures of products 4a–4l were determined by IR, 1H NMR, and 13C NMR spectroscopy as well as mass spectrometry (ESI).

Table 2 Synthesis of spiroacenaphthylene-pyranopyrazole derivatives 4a–4l
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Synthesis of spiroacenaphthylene-pyranopyrazole derivatives without using of catalyst with acenaphthoquinone undergos a smooth reaction with special pyrazolones and activated methylene reagents (malononitrile derivatives) to reported. The yields obtained were excellent without formation of any side products, and also products are obtained in very good purity passed microanalysis (Table 2). The reaction mixture was filtered and washed with EtOH/H2O, and the product dried without further purification. Also, the catalyst-free reactions performed in H2O are significantly safer, nontoxic environmentally friendly, and inexpensive. The absence of catalyst for the reaction avoids the use of dampness-sensitive and heavy metal materials, such as Lewis acids. This work is applicable for the synthesis of different types of spiro-pyranopyrazole acenaphthylene derivative. The mass spectra of these products displayed molecular ion peaks at the appropriate m/z values. The present procedure has the advantage that not only the reaction is performed under neutral conditions but also the reactants can be mixed without any activation or modification. The simplicity of the present procedure makes it an interesting alternative to complex multi-step approaches. A presumable mechanism for the formation of product is showed in Scheme 2. Firstly, addition of acenaphthoquinone to pyrazolone leads to the formation of Knoevenagel product 5 then added activated methylene reagent (malononitrile derivatives) to intermediate 5 would give product 4.

Scheme 2
scheme 2

Proposed mechanism for the formation of 4

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Conclusion

We have reported an efficient, catalyst-free, three-component method of acenaphthenequinone, pyrazolone derivatives, and malononitrile in water to give spiroacenaphthylene-pyranopyrazole derivatives in high yields under suitable conditions. The present procedure has the advantages including excellent selectivity, mild conditions, clean and simple workup and no need to isolate the products with column chromatography.

Experimental section

General remarks

All of the chemicals used in this work were purchased from Merck and Aldrich Chemical Companies. Melting points were measured on an Electrothermal 9100 apparatus. IR spectra were recorded in KBr disks on a Shimadzu IR-460 spectrometer, and absorbencies are reported in cm−1. 1H and 13C NMR spectra were measured with a Bruker DRX-300AVANCE spectrometer at 299.87 MHz. NMR spectra were obtained in solutions of DMSO-d6 using TMS as internal standard in ppm. Mass spectra were recorded on an Agilent Technologies 5975C VL MSD with Tripe-Axis Detector mass spectrometer operating at an ionization potential of 70 eV.

General procedure for the synthesis of product 4a

Typical procedure for preparation of 6′-amino-1′-(2-chlorophenyl)-3′-methyl-2-oxo-1′H,2H-spiro[acenaphthylene-1,4′-pyrano[2,3-c]pyrazole]-5′-carbonitrile (4a) (95% yield).

A mixture of acenaphthoquinone 1 (0.182 g, 1 mmol), 1-(2-chlorophenyl)-3-methyl-2-pyrazolin-5-one 2a (0.208 g, 1 mmol), H2O (5 ml), was stirred at reflux condition for 1 h was then added component 3 (malomonitrile) (0.066 g, 1 mmol) in the similar condition. Upon completion, monitored by TLC on silica gel using a 1:1 mixture of ethyl acetate/n-hexane, the reaction mixture was allowed to cool to 4 °C 2 h (Or to room temperature). The reaction mixture was filtered to give a pure product 4a (95% yield). Spiroacenaphthylene derivatives were analytically pure without recrystallization.

6′ - Amino - 1′ - (2 - chlorophenyl) - 3′ - methyl - 2 - oxo - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carbonitrile (4a)

Yellow solid, Yield, (95%). Mp: 188–190 °C, IR (KBr), νmax: 3339, 3165 (NH2), 2198 (CN), 1717 (C=O), 1653 (C=C), 1529, 1391, 1139 (C–O), 768 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 1.03 (3 H, s, CH3), 7.51–7.60 (m, 5 H, ArH), 7.65–7.74 (m, 2 H, ArH), 7.80 (t, 3JHH = 8 Hz, 1 H, ArH), 7.93 (t, 3JHH = 8 Hz, 1 H, ArH), 8.09 (d, 3JHH = 8 Hz, 2 H, ArH), 8.42 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.4, 52.7 (Cspiro), 57.3, 96.3, 118.6, 122.1, 123.2, 125.8, 128.9, 129.6, 130.0, 130.4, 130.5, 130.8, 131.0, 131.4, 131.9, 133.3, 134.3, 141.1, 141.6, 144.6, 146.6, 161.6, 203.9 (C=O). MS (EI) m/z (%): 438 (M+, 0.8), 372 (36), 344 (19), 309 (25), 230 (100), 202 (80), 173 (59), 139 (28), 111 (42), 75 (30), 63 (17). Anal. Calcd. for C25H15ClN4O2 (438.87): C, 68.42; H, 3.45; N, 12.77. Found: C, 68.1; H, 3.9; N, 12.5.

6′ - Amino - 3′ - methyl - 2 - oxo - 1′ - phenyl - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carbonitrile (4b)

Pale green solid, Yield, (92%). Mp: 196–198 °C, IR (KBr), νmax: 3372, 3314 (NH2), 2198 (CN), 1707 (C=O), 1651 (C=C), 1526, 1433, 1142 (C–O), 771 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 1.03 (s, 3 H, CH3), 7.34 (t, 3JHH = 8 Hz, 1 H, ArH), 7.51 (t, 3JHH = 8 Hz, 2 H, ArH), 7.58 (d, 3JHH = 8 Hz, 1 H, ArH), 7.66 (s, 2 H, ArH), 7.75–7.80 (m, 3 H, ArH), 7.92 (t, 3JHH = 8 Hz, 1 H, ArH), 8.06–8.10 (m, 2 H, ArH), 8.41 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.4, 52.6 (Cspiro), 57.3, 97.6, 118.6, 120.7, 122.3, 123.3, 125.8, 127.1, 129.6, 129.9, 130.0, 130.5, 130.9, 133.4, 137.7, 140.9, 141.6, 144.3, 145.4, 161.5, 204.0 (C=O).

6′ - Amino - 1′ - (3 - chlorophenyl) - 3′ - methyl - 2 - oxo - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carbonitrile (4c)

Yellow solid, Yield, (90%). Mp: 228–230 °C, IR (KBr), νmax: 3314, 3192 (NH2), 2198 (CN), 1716 (C=O), 1654 (C=C), 1591, 1518, 1433, 1135 (C–O), 993, 836, 674 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 1.04 (3 H, s, CH3), 7.40 (d, 3JHH = 8 Hz, 1 H, ArH), 7.70–7.60 (m, 2 H, ArH), 7.75–7.82 (m, 5 H, ArH), 7.92 (t, 3JHH = 8 Hz, 1 H, ArH), 8.07–8.10 (m, 2 H, ArH), 8.42 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.4, 52.7 (Cspiro), 57.3, 96.3, 118.6, 122.1, 123.2, 125.8, 128.9, 129.6, 130.0, 130.4, 130.5, 130.8, 131.0, 131.4, 131.9, 133.3, 134.3, 141.1, 141.6, 144.6, 146.6, 161.6, 203.9 (C=O). MS (EI) m/z (%): 440 (M++2, 14), 438 (M+, 38), 412 (59, –CN), 372 (19), 343 (17), 243 (100), 208 (34), 176 (27), 139 (12), 111 (39), 75 (24). Anal. Calcd. for C25H15ClN4O2 (438.87): C, 68.42; H, 3.45; N, 12.77. Found: C, 68.7; H, 3.2; N, 12.5.

6′ - Amino - 1′ - methyl - 2 - oxo - 3′ - (trifluoromethyl) - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carbonitrile (4d)

White solid, Yield, (93%). Mp: 264–266 °C, IR (KBr), νmax: 3388, 3305 (NH2), 2193 (CN), 1722 (C=O), 1642 (C=C), 1561, 1498, 1394, 1298, 1158 (C–O), 783 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 3.84 (3 H, s, CH3), 7.49 (d, 3JHH = 8 Hz, 1 H, ArH), 7.67–7.74 (m, 3 H, ArH), 7.87 (t, 3JHH = 8 Hz, 1 H, ArH), 8.03 (d, 3JHH = 8 Hz, 2 H, ArH), 8.36 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 35.5, 52.0 (Cspiro), 58.1, 96.3, 118.1, 122.0, 123.2, 125.8, 127.2, 129.4, 129.7, 130.4, 130.7, 133.1, 133.7, 141.3, 141.6, 147.0, 160.5, 203.3 (C=O). MS (EI) m/z (%): 396 (M+, 96), 370 (94, –CN), 324 (10), 297 (100), 250 (40), 188 (14), 43 (39). Anal. Calcd. for C20H11F3N4O2 (396.33): C, 60.61; H, 2.80; N, 14.14. Found: C, 60.3; H, 2.4; N, 14.5.

Ethyl - 6′ - amino - 1′ - (3 - chlorophenyl) - 3′ - methyl - 2 - oxo - 1′H,2H - spiro[acenaphthylene - 1,4′ - prano[2,3 - c]pyrazole] - 5′ - carboxylate (4e)

Colorless solid, Yield, (94%). Mp: 217–218 °C, IR (KBr), νmax: 3380, 3277 (NH2), 2977, 1697 (C=O), 1645 (C=C), 1596, 1512, 1432, 1383, 1132 (C–O), 987, 771 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 0.9 (3 H, s, CH3), 7.37 (t, 3JHH = 8 Hz, 2 H, ArH), 7.52 (t, 3JHH = 8 Hz, 1 H, ArH), 7.63 (t, 3JHH = 8 Hz, 1 H, ArH), 7.82–7.85 (m, 3 H, ArH), 7.93 (d, 3JHH = 8 Hz, 1 H, ArH), 8.00 (d, 3JHH = 8 Hz, 1 H, ArH), 8.30 (d, 3JHH = 8 Hz, 3 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.6, 12.9, 52.4 (Cspiro), 59.1, 75.8, 100.1, 118.7, 119.8, 120.4, 121.9, 124.5, 126.7, 128.9, 129.5, 130.1, 131.6, 132.2, 133.1, 134.3, 138.9, 141.2, 144.5, 144.8, 145.3, 161.9, 168.2, 205.1 (C=O). MS (EI) m/z (%): 485 (M+, 2), 412 (100, –CO2Et), 373 (23), 277 (10), 208 (8), 176 (25), 111 (19), 75 (11). Anal. Calcd. for C27H20ClN3O4 (485.11): C, 66.74; H, 4.15; N, 8.65. Found: C, 66.3; H, 3.8; N, 8.3.

Ethyl - 6′ - amino - 3′ - methyl - 2 - oxo - 1′ - phenyl - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4f)

Colorless solid, Yield, (91%). Mp: 203–204 °C, IR (KBr), νmax: 3392, 3273 (NH2), 2975, 1701 (C=O), 1646 (C=C), 1514, 1383, 1268, 1132 (C–O), 777 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 1.01 (3 H, s, CH3), 7.33–7.36 (m, 2 H, ArH), 7.50 (t, 3JHH = 8 Hz, 2 H, ArH), 7.63 (t, 3JHH = 8 Hz, 1 H, ArH), 7.81 (d, 3JHH = 8 Hz, 2 H, ArH), 7.86 (d, 3JHH = 8 Hz, 1 H, ArH), 7.93 (d, 3JHH = 8 Hz, 1 H, ArH), 8.00 (d, 3JHH = 8 Hz, 1 H, ArH), 8.24 (s, 2 H, ArH), 8.29 (d, 2JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.6, 12.8, 19.1, 52.5 (Cspiro), 59.1, 75.9, 99.7, 120.3, 120.5, 121.8, 124.4, 126.9, 128.9, 129.5, 129.9, 130.1, 132.1, 133.1, 137.8, 141.2, 144.3, 144.5, 145.0, 161.9, 162.0, 168.2, 205.1 (C=O). MS (EI) m/z (%): 452 (M++1, 10), 451 (M+, 7), 378 (100, –CO2Et), 339 (79), 309 (41), 277 (13), 232 (11), 205 (23), 176 (31), 77 (63). Anal. Calcd. for C27H21N3O4 (451.48): C, 71.83; H, 4.69; N, 9.31. Found: C, 72.3; H, 4.3; N, 9.1.

Ethyl - 6′ - amino - 1′ - (2 - chlorophenyl) - 3′ - methyl - 2 - oxo - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4 g)

Yellow solid, Yield, (95%). Mp: 210–212 °C, IR (KBr), νmax: 3373, 3271 (NH2), 2972, 1688 (C=O), 1647 (C=C), 1514, 1379, 1265, 1096 (C–O), 770 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 0.9 (3 H, s, CH3), 7.31 (d, 3JHH = 8 Hz, 1 H, ArH), 7.49–7.57 (m, 2 H, ArH), 7.63–7.73 (m, 3 H, ArH), 7.85–8.14 (m, 5 H, ArH), 8.30 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.6, 12.8, 52.6 (Cspiro), 59.1, 76.0, 98.3, 120.1, 121.8, 124.4, 128.8, 128.9, 129.6, 130.1, 130.4, 130.8, 131.3, 131.7, 132.1, 133.2, 134.5, 141.1, 144.8, 145.2, 145.4, 162.1, 168.3, 205.1 (C=O). MS (EI) m/z (%): 486 (M++1, 10), 485 (M+, 3), 412 (100, –CO2Et), 372 (71), 359 (3), 309 (65), 277 (8), 233 (14), 176 (59), 111 (47), 75 (26). Anal. Calcd. for C27H20ClN3O4 (485.11): C, 66.74; H, 4.15; N, 8.65. Found: C, 66.3; H, 4.5; N, 8.2.

Ethyl - 6′ - amino - 1′ - methyl - 2 - oxo - 3′ - (trifluoromethyl) - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4h)

White solid, Yield, (92%). Mp: 244–246 °C, IR (KBr), νmax: 3386, 3286 (NH2), 2987, 1681 (C=O), 1637 (C=C), 1506, 1385, 1279, 1170, 1119 (C–O), 776 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: − 0.12 (3 H, s, CH3), 0.86 (2 H, s, CH2), 3.82 (3 H, s, CH3), 7.28 (d, 3JHH = 8 Hz, 1 H, ArH), 7.56 (t, 3JHH = 8 Hz, 1 H, ArH), 7.79 (t, 3JHH = 8 Hz, 1 H, ArH), 7.89 (t, 3JHH = 8 Hz, 2 H, ArH), 8.23 (d, 3JHH = 8 Hz, 3 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.4, 35.3, 52.2 (Cspiro), 59.2, 76.4, 120.2, 121.6, 122.2, 124.6, 124.8, 128.6, 129.1, 130.2, 131.6, 133.4, 141.4, 145.1, 145.8, 161.1, 161.2, 168.0, 204.6 (C=O). MS (EI) m/z (%): 443 (M+, 1), 370 (100, –CO2Et), 342 (11), 295 (11), 250 (16), 208 (81), 43 (16). Anal. Calcd. for C22H16F3N3O4 (443.11): C, 59.60; H, 3.64; N, 9.48. Found: C, 59.3; H, 3.9; N, 9.2.

Methyl - 6′ - amino - 1′ - (3 - chlorophenyl) - 3′ - methyl - 2 - oxo - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4i)

Yellow solid, Yield, (95%). Mp: 223–224 °C, IR (KBr), νmax: 3380, 3281 (NH2), 2946, 1690 (C=O), 1645 (C=C), 1594, 1508, 1429, 1377, 1269, 1132 (C–O), 770 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 0.8 (3 H, s, CH3), 2.9 (3 H, s, CO2Me), 7.37 (t, 3JHH = 8 Hz, 2 H, ArH), 7.52 (t, 3JHH = 8 Hz, 1 H, ArH), 7.62 (t, 3JHH = 8 Hz, 1 H, ArH), 7.82–7.87 (m, 3 H, ArH), 7.92 (d, 3JHH = 8 Hz, 1 H, ArH), 7.99 (d, 3JHH = 8 Hz, 1 H, ArH), 8.23 (s, 2 H, ArH), 8.29 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.8, 50.75, 52.4 (Cspiro), 76.1, 100.2, 118.7, 119.8, 120.5, 121.8, 124.6, 126.7, 129.0, 129.5, 130.0, 131.1, 131.6, 132.1, 132.9, 134.3, 138.9, 144.6, 144.7, 145.2, 161.7, 168.3, 205.0 (C=O). MS (EI) m/z (%): 471 (M+, 0.1), 412 (50, –CO2Me), 372 (14), 343 (14), 263 (18), 208 (100), 176 (30), 151 (8), 111 (17), 70 (20). Anal. Calcd. for C26H18ClN3O4 (471.90): C, 66.18; H, 3.84; N, 8.90. Found: C, 66.7; H, 3.4; N, 8.7.

Methyl - 6′ - amino - 3′ - methyl - 2 - oxo - 1′ - phenyl - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4j)

Yellow solid, Yield, (94%). Mp: 209–210 °C, IR (KBr), νmax: 3376, 3279 (NH2), 2943, 1702 (C=O), 1644 (C=C), 1510, 1436, 1377, 1269, 1130 (C–O), 763 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 0.8 (3 H, s, CH3), 2.9 (3 H, s, CO2Me), 7.33 (d, 3JHH = 8 Hz, 2 H, ArH), 7.50 (t, 3JHH = 8 Hz, 2 H, ArH), 7.62 (t, 3JHH = 8 Hz, 1 H, ArH), 7.80 (d, 3JHH = 8 Hz, 2 H, ArH), 7.86 (d, 3JHH = 8 Hz, 1 H, ArH), 7.92 (d, 3JHH = 8 Hz, 1 H, ArH), 7.99 (d, 3JHH = 8 Hz, 1 H, ArH), 8.17 (s, 2 H, ArH), 8.29 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.8, 50.6, 52.6 (Cspiro), 76.2, 99.8, 120.3, 120.5 (2C), 121.7, 124.5, 126.9, 128.9, 129.5, 129.9 (2C), 130.0, 132.1, 133.0, 137.8, 140.8, 144.3, 144.4, 144.9, 161.8, 168.4, 205.0 (C=O). MS (EI) m/z (%): 437 (M+, 2), 405 (13), 378 (100, –CO2Me), 338 (63), 309 (75), 263 (11), 232 (9), 205 (15), 176 (33), 150 (13), 77 (68), 51 (17). Anal. Calcd. for C26H19N3O4 (437.46): C, 71.39; H, 4.38; N, 9.61. Found: C, 71.2; H, 4.6; N, 9.5.

Methyl - 6′ - amino - 1′ - (2 - chlorophenyl) - 3′ - methyl - 2 - oxo - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4k)

Yellow solid, Yield, (92%). Mp: 228–229 °C, IR (KBr), νmax: 3326, 3256 (NH2), 2986, 1726 (C=O), 1684, 1636 (C=C), 1514, 1436, 1379, 1278, 1136 (C–O), 769 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 0.8 (3 H, s, CH3), 2.8 (3 H, s, CO2Me), 7.29 (d, 3JHH = 8 Hz, 1 H, ArH), 7.54–7.72 (m, 5 H, ArH), 7.85–8.05 (m, 5 H, ArH), 8.29 (d, 3JHH = 8 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 12.7, 50.6, 52.8 (Cspiro), 76.3, 98.4, 120.2, 121.7, 124.5, 128.8, 128.9, 129.6, 130.0, 130.4, 130.8, 131.3, 131.7, 132.0, 133.0, 134.5, 140.7, 144.8, 145.1, 145.5, 161.9, 168.5, 204.9 (C=O). MS (EI) m/z (%): 472 (M++1, 4), 412 (100, –CO2Me), 372 (62), 344 (42), 309 (62), 263 (15), 233 (13), 205 (24), 176 (62), 139 (12), 111 (44), 75 (24). Anal. Calcd. for C26H18ClN3O4 (471.90): C, 66.18; H, 3.84; N, 8.90. Found: C, 66.4; H, 3.3; N, 8.6.

Methyl - 6′ - amino - 1′ - methyl - 2 - oxo - 3′ - (trifluoromethyl) - 1′H,2H - spiro[acenaphthylene - 1,4′ - pyrano[2,3 - c]pyrazole] - 5′ - carboxylate (4l)

Yellow solid, Yield, (93%). Mp: 236–238 °C, IR (KBr), νmax: 3382, 3282 (NH2), 2955, 1688 (C=O), 1638 (C=C), 1511, 1433, 1377, 1283, 1171, 1119 (C–O), 775 cm−1. 1H NMR (300 MHz, DMSO-d6) δ: 2.83 (3 H, s, CH3), 3.8 (3 H, s, CO2Me), 7.27 (d, 3JHH = 8 Hz, 1 H, ArH), 7.52–7.59 (m, 1 H, ArH), 7.76–7.81 (m, 1 H, ArH), 7.86–7.91 (m, 3 H, ArH), 8.14–8.15 (m, 1 H, ArH), 8.22–8.24 (m, 1 H, ArH). 13C NMR (75 MHz, DMSO-d6) δ: 35.3, 50.6, 52.3 (Cspiro), 76.8, 97.9, 120.3, 121.9, 122.2, 124.6, 124.7, 128.6, 129.1, 130.1, 131.5, 133.3, 133.7, 141.0, 145.0, 145.9, 160.9, 168.1. MS (EI) m/z (%): 429 (M+, 0.9), 370 (100, –CO2Me), 342 (12), 295 (12), 250 (20), 201 (9), 163 (5), 43 (15). Anal. Calcd. for C21H14F3N3O4 (429.36): C, 58.75; H, 3.29; N, 9.79. Found: C, 58.4; H, 3.7; N, 9.5.