Method for synthesizing chiral tricyclic benzofuran compounds
A kind of technology of benzofuran and compound, applied in the field of asymmetric synthesis in organic chemistry
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Embodiment 1
[0025] Taking 2-nitrobenzofuran 1a and MBH carbonate 2a to generate 3aa as an example, the reaction conditions are optimized, and the reaction equation is as follows:
[0026]
[0027]
[0028] a Unless otherwise specified, the reaction steps are as follows: 1a (0.1mmol), 2a (0.2mmol), catalyst (10mol%), 1.0mL solvent, in N 2 React under protection for 12 hours. b The separation yield, d.r>20:1, was determined by NMR testing the crude product. c Determined by chiral HPLC analysis. d 2a (0.15 mmol). e 2a (0.12 mmol). f C6 (7.5 mol%). g C6 (5 mol%). DCE = 1,2-dichloroethane, NR = no reaction.
[0029] During the screening of the reaction conditions, the effect of the catalyst on the reaction was first investigated (entries 1-7). At the same time, by comparing the effects of different solvents, temperatures, equivalent ratios of raw materials, and catalyst dosage on the reaction, it is finally determined that C6 is the best catalyst, CHCl3 is the best reaction solve...
Embodiment 2
[0032]
[0033] To a 10 mL Schlenk tube was added 2-nitrobenzofuran 1a (16.3 mg, 0.1 mmol), MBH carbonate 2d (61.2 mg, 0.2 mmol) and C6 (3.6 mg, 0.01 mmol). Seal the tube with a threaded rubber stopper, replace with nitrogen 3 times, then add CHCl via syringe 3 (1.0 mL). The mixture was stirred at 0 °C for 12 hours. Track the reaction with TLC. After the reaction is complete, use ethyl acetate / petroleum ether (volume ratio 1 / 15) to purify the reaction mixture by preparative thin-layer chromatography to obtain 32.3 mg of light yellow solid product 3ad, yield 92%, dr value >20 / 1, 94% ee. [ɑ] D 26 =-75.71 (c=0.87, CH2 Cl 2 ).m.p.:126-128℃.HPLC CHIRALCEL IA,n-hexane / 2-propanol=90 / 10,flow rate=0.8mL / min,temperature=25℃,λ=256nm,retention time:7.633min(major) ,12.413min(minor).TLC:R f =0.28(petroleum ether:ethyl acetate=15:1)[UV] 1 H NMR (400MHz, CDCl 3 )δ7.25-7.20(m,2H),7.18-7.13(m,4H),7.02(t,J=7.6Hz,1H),7.00(d,J=8.0Hz,1H),6.91(d,J =2.0Hz, 1H), 4.32(d, J=2.8Hz, 1H), 4.2...
Embodiment 3
[0035]
[0036] To a 10 mL Schlenk tube was added 2-nitrobenzofuran 1a (16.3 mg, 0.1 mmol), MBH carbonate 2e (62.0 mg, 0.2 mmol) and C6 (3.6 mg, 0.01 mmol). Seal the tube with a threaded rubber stopper, replace with nitrogen 3 times, then add CHCl via syringe 3 (1.0 mL). The mixture was stirred at 0 °C for 12 hours. Track the reaction with TLC. After the reaction is complete, use ethyl acetate / petroleum ether (volume ratio 1 / 15) to purify the reaction mixture by preparative thin-layer chromatography to obtain 30.9 mg of light yellow solid product 3ae, yield 87%, dr value >20 / 1, 94% ee. [ɑ] D 26 =-39.59 (c=0.94, CH 2 Cl 2 ).m.p.:42-43℃.HPLC CHIRALCEL ID, n-hexane / 2-propanol=90 / 10, flow rate=0.8mL / min, temperature=25℃, λ=256nm, retention time:9.032min(major) ,10.513min(minor).TLC:R f =0.24(petroleum ether:ethyl acetate=15:1)[UV] 1 H NMR (400MHz, CDCl 3 )δ7.32-7.26(m,3H),7.25-7.23(m,1H),7.08-7.03(m,3H),7.00(d,J=8.0Hz,1H),6.95(d,J=2.0Hz ,1H),4.33(d,J=2.8Hz,1H),4.29(t...
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