一二三四区视频,亚洲少妇熟女色,日本久热无码视频网,欧美国产日韩大尺度,亚洲a视频,久久少妇一区二区,日韩999无码视频,刺激久久久久久久,啊啊啊啊不要啊在线

Welcome to chemicalbook!
Chinese English Japanese Germany Korea
010-86108875
Try our best to find the right business for you.
Do not miss inquiry messages Please log in to view all inquiry messages.

Welcome back!

ChemicalBook CAS DataBase List Entecavir
142217-69-4

Entecavir synthesis

11synthesis methods
Entecavir is synthesized from 4-trimethylsilyl-3-butyn-2-one and acrolein. The key features of its preparation are: (1) a stereoselective boron–aldol reaction to afford the acyclic carbon skeleton of the methylenecylopentane moiety; (2) its cyclization by a Cp2TiCl-catalyzed intramolecular radical addition of an epoxide to an alkyne; and (3) the coupling with a purine derivative by a Mitsunobu reaction.142217-69-4.png
-

Yield:142217-69-4 60%

Reaction Conditions:

Stage #1: ((1 R,3S,5S)-5-acetoxy-3-(2-amino-6-chloro-9H-purin-9-yl)-2-methylenecyclopentyl)methyl acetatewith sodium hydroxide at 80; for 2 h;
Stage #2: with hydrogenchloride in water at 0; pH=7;

Steps:

14

Example 14 Preparation of entecavir To (II) (0.4 g, 1.05 mmol) at room temperature, a 2.5 M solution of NaOH (10 mL) was added. The reaction mixture was heated to 80 °C for 2 h. The reaction mixture was cooled to 0 °C and neutralized with HCl to pH = 7. Decolorizing carbon (0.5 g) was added and the mixture was heated at 90 °C for 1 h. The hot mixture was filtered through Celite. The filtrate was cooled under stirring to effect crystallization. The estimated yield was 60 % approximately.

References:

EP2474548,2012,A1 Location in patent:Page/Page column 19

Entecavir Related Search:

浮梁县| 江川县| 古交市| 凤翔县| 徐州市| 定南县| 阳春市| 四川省| 武胜县| 大新县| 郧西县| 清新县| 阜南县| 海门市| 安国市| 聂拉木县| 新竹市| 罗定市| 闽清县| 五台县| 任丘市| 固原市| 益阳市| 蓬莱市| 时尚| 嘉黎县| 资溪县| 花莲市| 隆回县| 广宗县| 咸宁市| 体育| 黄冈市| 淳化县| 大同市| 韶山市| 朝阳区| 九江市| 花垣县| 措勤县| 巴里|