Molecules 2018, 23, 3002
7 of 9
7-Hydroxy-6-isopentenyl-4-methylbenzopyran-2-one (
5
): White solid; yield: 30%; m.p., 83–84 ◦C; ESI-MS
1
m/z: 245.3 [M + H]+. H-NMR (CHCl3-d, 400 MHz)
δ: 1.70 (s, 3H), 1.83 (s, 3H), 2.41 (s, 3H), 3.30 (d, 2H,
J = 6.0 Hz), 4.08 (t, 1H, J = 6.0 Hz), 6.09 (s, 1H), 6.69 (d, 1H, J = 2.0 Hz), 6.79–6.82 (dd, 1H, J = 8.8 Hz,
J = 2.4Hz), 7.58 (d, 1H, J = 8.8 Hz); 13C-NMR (CHCl3-d, 100 MHz)
: 17.24, 19.34, 22.4, 24.62, 102.06,
109.82, 112.44, 112.94, 115.1, 125.20, 126.03 154.56, 155.15, 161.63, 162.46.
δ
◦
1,4-Di(6-isopentenyl-4-methylbenzopyran-2-one-7-oxy)butane (
6
): White solid; yield: 20%; m.p.,162–164 C;
:1.28 (s, 6H), 1.35 (s, 6H), 2.03–2.07 (m,
1
ESI-MS m/z: 529.6 [M + H]+. H-NMR (CHCl3-d, 400 MHz)
δ
4H), 2.44 (s, 6H, J = 6.0 Hz), 3.26 (d, 4H, J = 6.0 Hz), 4.05 (d, 2H, J = 8.0 Hz), 4.60 (d, 2H, J = 8.0 Hz),
6.06 (s, 2H), 6.16 (s, 2H), 6.90 (d, 2H, J = 8.8 Hz), 6.98 (dd, 2H, J = 8.8 Hz, J = 2.0 Hz), 7.68 (d, 2H,
J = 9.6 Hz); 13C-NMR (CHCl3-d, 100 MHz)
δ: 17.25, 19.11, 19.33, 24.92, 30.68, 63.69, 67.78, 101.25, 112.69,
125.95, 127.62, 128.17, 128.98, 129.84, 154.29, 155.00, 162.11
3.4. General Procedure for the Preparation of Compound 7
Benzoylcyanide (3 mmol) was dissolved in hydrochloric acid (10 mL) with stirring at room
temperature for 2h. Then, the products were filtered out and added into methanol. Concentrated
H2SO4 (1 mL) was added to the mixture and refluxed. After that, the mixture was extracted
with ethyl acetate and evaporated to yield the crude products, which reacted with compound 2c
without purification catalyzed by AlCl3. The crude products were further purified by means of silica
chromatography to provide compound 7 (Scheme 2).
1-(4-Methylbenzopyran-2-one-7-oxy)-4-(3-methylphenylglyoxylate)butane (
7
): White solid; yield: 30%;
1
m.p.,117–119 ◦C; ESI-MS m/z: 395.4 [M + H]+. H-NMR (CHCl3-d, 400 MHz)
δ: 1.22–1.27 (m, 2H),
1.71–1.79 (m, 2H), 2.40 (s, 3H), 2.86–2.91 (m, 2H), 3.68 (s, 3H), 4.14–4.18 (m, 2H), 6.16 (s, 1H), 6.85 (dd,
1H, J = 8.4 Hz, 2.4 Hz), 7.48 (t, 1H, J = 8.4 Hz), 7.57(dd, 1H, J = 8.0 Hz, 2.4 Hz), 7.62 (t, 1H, J = 8.4 Hz),
7.70–7.73 (m, 2H), 8.11(d, 1H, J = 8.0 Hz); 13C-NMR (CHCl3-d, 100 MHz)
δ: 18.73, 22.73, 29.71, 31.68,
52.34, 68.70, 103.39, 111.63, 112.50, 113.07, 113.57, 125.41, 125.96, 128.51, 130.20, 133.72, 145.2, 152.7,
153.15, 155.12, 159.71, 161.89, 170.43.
3.5. General Procedure for the Preparation of Compound 8
Compound 2c (2.0 mmol) was added to a solution of 3-aminophenol (2.5 mmol), KOH (1 mmol),
and K2CO3 (3 mmol) in acetone (10 mL). The mixture was heated at reflux for 3 h and the reaction
was detected with TLC. The mixture was extracted with ethyl acetate and evaporated to get crude
product. The crude products were prepared by filtering the mixture and evaporating the solvent and
were further purified by silica chromatography to give compound 8 (Scheme 3).
1-(4-Met◦hylbenzopyran-2-one-7-oxy)-4-(3-aminophenol) butane (
8
): White solid; yield: 54%; m.p.,
1
123–125 C; ESI-MS m/z: 340.4 [M + H]+. H-NMR (CHCl3-d, 400 MHz)
δ
: 1.23–1.28 (m, 2H), 2.02–2.10
(m, 2H), 2.40 (s, 3H), 4.11 (s, 2H), 4.51–4.57 (m, 2H), 4.62–4.66 (m, 2H), 6.02–6.09 (m, 1H), 6.14 (s, 1H),
6.19–6.34 (m, 2H), 6.85–6.89 (m, 1H), 7.05 (t, 1H, J = 8.4 Hz), 7.48 (t, 2H, J = 8.8 Hz); 13C-NMR (CHCl3-d,
100 MHz) δ: 18.69, 27.8(2), 67.32(2), 101.74, 104.69, 108.29, 112.08, 113.73, 126.88, 128.43, 129.56, 130.16,
147.81, 152.59, 155.12, 159.71, 161.34, 161.50.
3.6. General Procedure for the Preparation of Compounds 9 and 10
The amine (5.0 mmol) was dissolved in water, and NaHCO3 (10.0 mmol) was added with stirring.
After being cooled to 5 ◦C, Cbz-Cl (7.5 mmol) was added slowly in para-dioxane. Then, the mixture
◦
was stirred at 0 C for 1 h and allowed to warm to room temperature for 12 h. After the reaction,
water was added and extracted with ethyl acetate. The aqueous layers were acidified to pH of 1 and
extracted three times with ethyl acetate. The organic layers were dried with sodium sulfate, and the
solvent was evaporated to get compound
9
. Ethyl acetoacetate (2 mmol) was added to a mixt◦ure of
compound
9
(1 mmol) and phosphoric acid (10 mL). The mixture was heated with stirring at 80 C for