Unless otherwise noted, all reactions were carried out under Ar in flamed-dried glassware using anhydrous solvents. Anhydrous solvents were prepared by distillation over the indicated drying agents prior to use and were transferred under Ar: THF, Et2O (Mg/anthracene), toluene (Na/K), CH2Cl2, MeOH (Mg); DMF and Et3N were dried by an adsorption solvent purification system based on molecular sieves. Thin layer chromatography (TLC): Macherey–Nagel precoated plates (POLYGRAM®SIL/UV254). Flash chromatography: Merck silica gel 60 (40−63 µm) with technical grade solvents. NMR: Spectra were recorded on Bruker AV VIII 400 or 600 spectrometers in the solvents indicated. The solvent signals were used as references, and the chemical shifts were converted to the TMS scale (CDCl3: δC = 77.0 ppm; residual CHCl3 in CDCl3: δH = 7.26 ppm; CD3OD: δC = 49.0 ppm; residual CHD2OD in CD3OD: δH = 3.31 ppm; CD2Cl2: δC = 54.0 ppm; residual CHDCl2 in CD2Cl2: δH = 5.32 ppm). FT-IR spectra were obtained on Thermo Scientific Nicolet 6700 and reported in frequency of the absorption (cm−1). High resolution mass spectra (HRMS) were recorded on an AB SCIEX Q-TOF 5600 mass spectrometer. Optical rotation (({[alpha ]}_{D}^{20}) and ({[alpha ]}_{D}^{25})): Krüss P8000-T, 10 cm/1 mL cell. Unless otherwise noted, all commercially available compounds (Acros, Aldrich, Alfa Aesar, TCI) were used as received. Melting points were determined on a A. KRÜSS OPTRONIC M3000.

Decursin (compound 1)

N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (0.392 g, 2.00 mmol, 2 equiv) and DMAP (0.0489 g, 0.0400 mmol, 0.4 equiv) were added to a stirred mixture of 3-methyl crotonic acid (0.120 g, 1.20 mmol, 1.2 equiv) and decursinol (0.246 g, 1.00 mmol) in CH2Cl2 (8 mL) at room temperature. After stirring overnight, the reaction was quenched with H2O. After phase separation, the aqueous layer was rinsed with ethyl acetate. The organic extracts were combined, dried over Na2SO4, and concentrated in vacuo. Purification of the crude product by flash chromatography (hexane:EtOAc, 7:3) gave the title compound as a white solid (0.199 g, 60.6%). Rf – 0.80 (50% EtOAc: 50% Hexane); 1H NMR (400 MHz, Chloroform-d) δ 7.57 (d, J = 9.4 Hz, 1H), 7.14 (s, 1H), 6.78 (s, 1H), 6.23 (d, J = 9.4 Hz, 1H), 5.66 (s, 1H), 5.07 (app.t, J = 4.9 Hz, 1H), 3.18 (dd, J = 17.1, 4.8 Hz, 1H), 2.85 (dd, J = 17.1, 4.8 Hz, 1H), 2.13 (s, 3H), 1.87 (s, 3H), 1.37 (s, 3H), 1.35 (s, 3H); 13C NMR (101 MHz, Chloroform-d) δ 165.9, 161.4, 158.6, 156.6, 154.3, 143.3, 128.8, 116.1, 115.7, 113.4, 112.9, 104.8, 76.9, 69.2, 28.0, 27.6, 25.1, 23.3, 20.5; HR-MS (ESI): m/z calcd for C19H21O5+ [M + H]+: 329.1384, found 329.1384

Spectral characteristics were identical to those previously reported [13].

(S)-8,8-Dimethyl-2-oxo-7,8-dihydro-2H,6H-pyrano[3,2-g]chromen-7-yl (E)-2-methylbut-2-enoate (compound 2)

N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (0.636 g, 3.24 mmol, 2 equiv) and DMAP (0.0792 g, 0.648 mmol, 0.4 equiv) were added to a stirred mixture of Tiglic acid (0.195 g, 1.95 mmol, 1.2 equiv) and decursinol (0.400 g, 1.62 mmol) in CH2Cl2 (8 mL) at room temperature. After being stirred at this temperature overnight, the reaction was quenched with H2O. After phase separation, the aqueous layer was rinsed with ethyl acetate. The organic extracts were combined, dried over MgSO4, and concentrated in vacuo. Purification of the crude product by flash chromatography (hexane:EtOAc, 7:3) gave the title compound as transparent oil (0.465 g, 87.5%). Rf – 0.69 (50% EtOAc: 50% Hexane); 1H NMR (400 MHz, Chloroform-d) δ 7.58 (d, J = 9.5 Hz, 1H), 7.15 (s, 1H), 6.84 – 6.78 (m, 2H), 6.23 (d, J = 9.5 Hz, 1H), 5.08 (t, J = 5.0 Hz, 1H), 3.25 – 3.15 (m, 1H), 2.88 (dd, J = 17.2, 5.3 Hz, 1H), 1.82 – 1.78 (m, 3H), 1.76 (m, 3H), 1.39 (s, 3H), 1.37 (s, 3H); 13C NMR (101 MHz, Chloroform-d) δ 167.3, 161.4, 156.6, 154.4, 143.3, 138.6, 128.8, 128.3, 116.0, 113.5, 113.0, 104.8, 76.9, 70.3, 27.9, 25.2, 23.3, 14.6, 12.2; HR-MS (ESI): m/z calcd for C19H21O5+ [M + H]+: 329.1384, found 329.1383.

(S)-8,8-dimethyl-2-oxo-7,8-dihydro-2H,6H-pyrano[3,2-g]chromen-7-yl (E)-pent-2-enoate (compound 3)

A mixture of (S)-(+)-decurinol (0.144 g, 0.583 mmol, 1 equiv), N,N’-Dicyclohexylcarbodiimide (0.181 g, 0.875 mmol, 1.5 equiv), and 4-(dimethylamino)pyridine (0.0285 g, 0.233 mmol, 0.4 equiv) was dissolved in anhydrous dichloromethane. Then, trans-2-pentenoic acid (0.064 ml, 0.641 mmol, 1.1 equiv) was added, and the reaction mixture was stirred at room temperature overnight. The reaction mixture was then filtered through a pad of Celite with CH2Cl2, and the filtrate was concentrated in vacuo. Purification of the crude product by flash chromatography (hexane:EtOAc, 7:3) gave the title compound as a white solid (0.168 g, 88.3%). Rf – 0.68 (50% EtOAc: 50% Hexane); 1H NMR (400 MHz, Chloroform-d) δ 7.58 (d, J = 9.5 Hz, 1H), 7.15 (s, 1H), 7.04 (dt, J = 15.6, 6.3 Hz, 1H), 6.81 (s, 1H), 6.23 (d, J = 9.5 Hz, 1H), 5.80 (dt, J = 15.7, 1.7 Hz, 1H), 5.11 (app.t, J = 4.9 Hz, 1H), 3.20 (dd, J = 18.2, 4.9 Hz, 1H), 2.88 (dd, J = 17.2, 4.8 Hz, 1H), 2.27 – 2.15 (m, 2H), 1.39 (s, 3H), 1.36 (s, 3H), 1.05 (t, J = 7.4 Hz, 3H); HR-MS (ESI): m/z calcd for C19H21O5+ [M + H]+: 329.1384, found 329.1383. Spectral characteristics were identical to those previously reported [14].

(S)-8,8-dimethyl-2-oxo-7,8-dihydro-2H,6H-pyrano[3,2-g]chromen-7-yl (Z)-3-chloroacrylate (compound 4)

A mixture of (S)-(+)-decurinol (0.202 g, 0.82 mmol, 1.0 equiv), N,N’-Dicyclohexylcarbodiimide (0.254 g, 1.23 mmol, 1.5 equiv), and 4-(dimethylamino)pyridine (0.040 g, 0.33 mmol, 0.4 equiv) was dissolved in anhydrous dichloromethane. Then, cis-chloro acrylic acid (0.096 g, 0.90 mmol, 1.1 equiv) was added, and the resulting mixture was stirred at room temperature overnight. The reaction mixture was then filtered through a pad of Celite with CH2Cl2, and the filtrate was concentrated in vacuo. Purification of the crude product by flash chromatography (hexane:EtOAc, 8:2) gave the title compound as a white solid (126.4 mg, 46.0%). %). Rf – 0.52 (50% EtOAc: 50% Hexane); M. p. 97.9–100.6 ℃;({[alpha ]}_{D}^{20}): + 195.8 (c = 0.1, CHCl3); 1H NMR (400 MHz, Chloroform-d) δ 7.58 (d, J = 9.2 Hz, 1H), 7.16 (s, 1H), 6.80 (s, 1H), 6.75 (d, J = 8.3 Hz, 1H), 6.24 (d, J = 9.5 Hz, 1H), 6.18 (d, J = 8.3 Hz, 1H), 5.15 (app.t, J = 4.9 Hz, 1H), 3.24 (ddd, J = 17.1, 4.8, 1.1 Hz, 1H), 2.92 (dd, J = 17.7, 5.0 Hz, 1H), 1.40 (s, 3H), 1.38 (s, 3H); 13C NMR (101 MHz, Chloroform-d) δ 162.8, 161.3, 156.4, 154.3, 143.3, 134.1, 128.8, 120.9, 115.6, 113.5, 113.0, 104.8, 76.5, 70.8, 27.8, 25.1, 23.2; IR(neat): 3100, 3046, 2982, 2921, 2849, 1721, 1625, 1564, 1516 cm−1 HR-MS (ESI): m/z calcd for C17H16ClO5+ [M + H]+: 335.0681, found: 335.0681.

(S)-8,8-dimethyl-2-oxo-7,8-dihydro-2H,6H-pyrano[3,2-g]chromen-7-yl (E)-3-chloroacrylate (compound 5)

To a solution of (S)-( +)-decurinol (0.207 g, 0.84 mmol, 1 equiv), N,N’-Dicyclohexylcarbodiimide (0.347 g, 1.68 mmol, 1.5 equiv), and 4-(dimethylamino)pyridine (0.0410 g, 0.356 mmol, 0.4 equiv) in anhydrous CH2Cl2 was added trans-chloro acrylic acid (0.0984 g, 0.924 mmol, 1.1 equiv). The reaction mixture was stirred at room temperature overnight. The reaction mixture was then filtered through a pad of Celite with CH2Cl2, and the filtrate was concentrated in vacuo. Purification of the crude product by flash chromatography (hexane:EtOAc, 8:2) gave the title compound as a white solid (69.8 g, 24.8%). Rf – 0.69 (50% EtOAc: 50% Hexane); M.p. 150.7–153.3 ℃;({[alpha ]}_{D}^{20}): + 55.0 (c = 0.2, CHCl3); 1H NMR (400 MHz, Chloroform-d) δ 7.58 (d, J = 9.5 Hz, 1H), 7.35 (d, J = 13.5 Hz, 1H), 7.15 (s, 1H), 6.79 (s, 1H), 6.27–6.19 (m, 2H), 5.13 (app.t, J = 4.7 Hz, 1H), 3.21 (dd, J = 17.3, 4.8 Hz, 1H), 2.89 (dd, J = 17.3, 4.6 Hz, 1H), 1.38 (s, 3H), 1.36 (s, 3H); 13C NMR (101 MHz, Chloroform-d) δ 163.5, 161.3, 156.3, 154.4, 143.2, 139.0, 128.8, 124.4, 115.4, 113.6, 113.1, 105.0, 76.5, 70.9, 27.9, 25.0, 23.4; IR(neat): 3020, 3085, 3005, 2927, 2851, 1714, 1622, 1604, 1560 cm−1; HR-MS (ESI) m/z calcd for C17H16ClO5+ [M + H]+: 335.0689, found: 335.0681.

(S)-8,8-dimethyl-2-oxo-7,8-dihydro-2H,6H-pyrano[3,2-g]chromen-7-yl (E)-3-(pyridin-4-yl)acrylate (compound 6)

N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (0.108 g, 0.55 mmol, 1.1 equiv) and DMAP (0.0061 g, 0.05 mmol, 0.1 equiv) were added to a stirred mixture of (E)-3-(pyridin-4-yl)acrylic acid (0.082 g, 0.55 mmol, 1.1 equiv) and decursinol (0.123 g, 0.50 mmol) in CH2Cl2 (5 mL) at room temperature. After being stirring at this temperature for 24 h, the reaction was quenched with H2O. After phase separation, the aqueous layer was rinsed with CH2Cl2. The organic extracts were combined, dried over Na2SO4, and concentrated in vacuo. Purification of the crude product by flash chromatography (hexane:EtOAc, 3:7) gave the title compound as a white solid (0.169 g, 89.6%). Rf – 0.32 (70% EtOAc: 30% Hexane); M.p. 211–215 °C;({[alpha ]}_{D}^{20})= + 53.9 (c = 0.25, CH2Cl2); 1H NMR (CDCl3, 400 MHz): δ 8.72–8.59 (m, 2H), 7.79–7.53 (m, 2H), 7.36–7.30 (m, 2H), 7.18 (s, 1H), 6.83 (s, 1H), 6.58 (d, J = 16.0 Hz, 1H), 6.24 (d, J = 9.4 Hz, 1H), 5.21 (app.t, J = 4.6 Hz, 1H), 3.26 (ddd, J = 17.2, 4.8, 1.2 Hz, 1H), 3.00–2.89 (m, 1H), 1.44 (s, 3H), 1.39 (s, 3H); 13C NMR (CDCl3, 151 MHz): δ 165.3, 161.3, 156.4, 154.4, 149.6, 143.2, 142.6, 142.5, 128.8, 123.1, 122.4, 115.4, 113.7, 113.2, 105.0, 76.6, 71.0, 28.0, 25.0, 23.6; IR (film): 3067, 2981, 2931, 2852, 1724, 1626, 1562, 1515, 1135 cm−1; HRMS: Calcd for C22H20NO5+ [M + H]+ 378.1336, found 378.1342.

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