synthesis method | method 1: take 5-bromo -4-chlorine -3-indole -2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside and dissolve it in 15mL of methanol, cool to 0 ℃ in ice bath; Then add 3mL(0.5mol/L) of sodium methoxide methanol solution dropwise and stir for 5 hours at this temperature. After the reaction is over, pour the reaction solution into the pre-treated cation exchange resin (pretreatment method of cationic resin: rinse the resin with clear water first; Then soak in 5% hydrochloric acid for about 4 hours and wash to neutral. Soak in 5% sodium hydroxide solution for about 4 hours, wash with water to neutral; Finally, soak in 5% hydrochloric acid for 4 hours and wash to neutral), stir slowly for 5~10min, filter, rinse with methanol, evaporate the filtrate to remove the solvent to obtain 0.49g of white solid 5-bromo -4-chloro -3-indolyl-beta-D-glucopyranoside with a yield of 81.6% and a melting point of 86.5 ℃. Method 2: 40mg of compound 5 was dissolved in 5mL of methanol, cooled to 0 ℃ in an ice bath, then 5mL(0.2mol/L) of sodium methoxide methanol solution was added dropwise, and stirred at this temperature for 3 hours. After the reaction is over, pour the reaction solution into the pre-treated cation exchange resin (pretreatment method is the same as section 1.2.1) and stir slowly for 5-10min. Filter, rinse with methanol, the filtrate was distilled to remove the solvent to obtain 10mg of white solid, namely 5-bromo-4-chloro-3-indolyl-beta-D-glucopyranoside, with a yield of 40.3% and a melting point of 82.1 ℃. |