New preparation method of tetrasubstituted furan compound
A four-substituted compound technology, applied in the field of furan preparation, can solve the problems of high pressure, high reaction temperature and long time, and achieve the effects of high selectivity, mild reaction conditions and easy separation
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Embodiment 1-17
[0019] The investigation of table 1 reaction condition a
[0020]
[0021]
[0022] a Reaction conditions: toluene (2.0mmol), catalyst (0.1mmol), base (0.1mmol) solvent (m / m mass ratio): 2 / 0.1, 80°C, 1atm O 2 , 6h.
[0023] b 1a tm air in 6h
[0024] c 1a tm air in 12h
[0025] As can be seen from Table 1, the effect of the catalyst on the reaction is obvious, and the reaction does not proceed without adding metal palladium catalyst, and no product is generated. Pd catalyst with PdCl 2 , Pd(CH 3 EN) 2 Cl 2 , (C 6 h 5 EN) 2 PdCl 2 As well, considering the cheapness and availability, PdCl 2 as well. The mixed solution of DMA and water was the best solvent, and the yield reached 82%. In order to obtain similar reaction results, a longer reaction time is required when air is the oxidant compared to oxygen. The effect of base is also very important, without the addition of base, the reaction will not go well. Only 10% product yield. The product yield obtai...
Embodiment 18-23
[0027] The impact of the consumption of table 2 water on reaction a
[0028] Example
DMA / H 2 O(m / m)
Yield (%)
18
2 / 0.05
35
19
2 / 0.1
83
20
2 / 0.5
84
21
2 / 1
79
22
1 / 2
80
23
0 / 2
45
[0029] a Reaction conditions: Tolan (2.0mmol), PdCl 2 (0.1mmol), NaOAc (0.2mmol) 60°C, 1atm O 2 , 12h.
[0030] It can be seen from the reaction phenomenon that the addition of water helps to improve the yield of the reaction, and also promotes the reaction to increase the reaction speed. However, increasing the amount of water to a certain extent will affect the solubility of the substrate, resulting in poor reaction results. The yield of product was only 45% without DMA addition. From the results in Table 2 we can see that DMA and H 2 The mass ratio of O is preferably 20:1-1:2.
Embodiment 24
[0032]
[0033] 1mmol 1,2-diphenylacetylene (1a), 0.05mmol PdCl 2 , 0.2mmol NaOAc, 10mL (mass ratio 9:1) N,N-dimethylacetamide and aqueous solution were added to a 50mL polytetrafluoroethylene-lined autoclave, and the autoclave was sealed, and the autoclave was pressurized to 0.3MPa with air , 80°C for 16h. After the reaction was finished, cool to room temperature, and carefully deflate and depressurize. 20 mL of water was added to the reaction solution, extracted three times with ether (30 mL x 3), the ether layer was dried over anhydrous sodium sulfate, the solvent was removed, and the oxidation product 2a was obtained by silica gel column chromatography with a yield of 84%. 1 H NMR (CDCl 3 , 400MHz) δ7.157.19 (m, 4H), 7.207.28 (m, 12H), 7.517.53 (m, 4H).
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