wittig反应为什么要求低温？(2S,3R)-Ethyl 3-((R)-2,2-dimethyl-1,3-dioxolan-4-yl)-2,3-dihydroxy-2-methylpropanoate (8). (Carbethoxyethylidene)triphenylmethylphosphorane (66.2 g, 182.6 mmol) was dissolved in anhydrous dichloromethane (250 mL) and the solution was cooled to -40 C with stirring under a nitrogen atmosphere. (R)-(þ-2,2-Dimethyl-1,3-dioxolane-4-carboxaldehyde (6, 25.0 g, 192.3 mmol) was dissolved in anhydrous dichloromethane(100 mL) and added to the reaction solution over 20 min at -40 C. The stirred reaction mixture was allowed to warm to ambient temperature for 17 h. The mixture was concentrated under reduced pressure to dryness and the residue was suspended in tert-butyl methyl ether (200 mL). The suspension was filtered to remove triphenylphosphine oxide and the filtrate was concentrated under reduced pressure to afford 25.8 g of crude alkene (7) 微信图片_20190123170623.jpg查看更多4个回答 . 19人已关注
求助FDA申报材料翻译？在某药品的临床申报材料中看到下面这句，求大神翻译··· Using pooled data across dose groups, the 90% confidence intervals of the CR:IR ratios for Cmax, AUC, and Ctau fell within an 80% to 125% equivalence interval. 这个药是 卡维地洛 ，治疗高血压的。查看更多7个回答 . 10人已关注
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