Ethyl bromonorcantharidin monoate and its preparation method and application
A technology of methylcantharidin monoacid ethyl ester and norcantharidin, which is applied in bromonorcantharidin monoacid ethyl ester and its preparation method and application field, can solve the problems that have not been reported, and achieve low cost and selective Good performance and high yield
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Embodiment 1
[0027] The preparation of embodiment 1 intermediate A, i.e. 5,6-dihydronorcantharidin: the reaction formula is as follows:
[0028]
[0029] Take out a certain amount of maleic anhydride from the reagent bottle, place it in a dry grinding body and grind it finely, then weigh 12.021g of the finely ground maleic anhydride with an electronic balance, put it in a dry three-necked flask, and plug it Stopper, add diethyl ether and stir, when the amount of diethyl ether is 90mL, the maleic anhydride is completely dissolved. After the maleic anhydride was completely dissolved, 13 mL of furan was slowly added through the dropping funnel for 13 minutes. The temperature was controlled to start the reaction at 38°C. After reacting for 1 h, white solids appeared in the solution, and the longer the time, the more white solids there were. After reacting for 24 hours, it was suction filtered to obtain white solid intermediate A, namely 5,6-dihydronorcantharidin. The dry weight is 17.459...
Embodiment 2
[0031] The preparation of embodiment 2 intermediate B, i.e. 5,6-dibromonorcantharidin: the reaction formula is as follows:
[0032]
[0033] Weigh 5 g of intermediate A obtained in Example 1, place it in a 250 mL two-necked flask, add 20 mL of chloroform and start stirring at room temperature until the reaction solution in the reaction system is stirred into a suspension. At this time, under stirring at room temperature, use a dropping funnel to add dropwise a mixture of 2.5mL chloroform and 0.5mL liquid bromine. After the addition is complete, rinse the dropping funnel with 2.5mL chloroform, and slowly add the rinse solution , Add the mixed solution and the rinse solution for a total of 20 minutes, and observe the phenomenon. After the reaction was completed, it was suction filtered and washed three times with carbon tetrachloride to obtain white solid intermediate B, namely 5,6-dibromonorcantharidin. The dry weight is 8.330g, and the yield is 85.35%. Melting point: 157-...
Embodiment 35
[0034] The preparation of embodiment 35,6-dibromonorcantharidin monoacid ethyl ester: the reaction formula is as follows:
[0035]
[0036] Weigh 0.500g of the intermediate B obtained in Example 2, place it in a round bottom flask, add 1.5mL of 95% ethanol, start stirring and raise the temperature to 78°C when the solution starts to reflux, then slowly add 95% ethanol drop by drop , until the solution became clear. Then suction filter while it is hot, seal the obtained filtrate, put it in the refrigerator, and start to crystallize. Overnight, the next day, a large number of white crystals appeared in the Erlenmeyer flask, which was filtered by suction to obtain a white solid, namely ethyl 5,6-dibromonorcantharidin monoate. The dry weight was 469mg, and the yield was 82%. Melting point: >240°C. Rf: 0.63 (developing solvent: petroleum ether: ethyl acetate = 10:1). 1 HNMR (DMSO-d6) δ: 12.64 (s, 1H), 4.77 (d, 2H), 4.41 (d, 1H), 4.01 (q, 2H), 3.34 (s, 2H), 3.21 (s, 1H), 1.1...
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