- Copper catalyzed coupling of protecting group free and sterically hindered 2-bromobenzyl tertiary alcohols with phenols and anilines: Facile synthesis of xanthenes and dihydroacridines
-
A simple and efficient method for the synthesis of xanthenes and dihydroacridines containing a quaternary carbon atom at the 9th-position, is presented. Significantly, the protocol facilitated the smooth participation of sterically hindered and protecting group free 2-bromobenzyl tertiary alcohols in cross coupling reactions with phenols and anilines, under copper-catalysis. The Lewis acid mediated intramolecular C-C bond formation enabled the formation of a quaternary carbon atom at the 9th-position. Remarkably, this two-step protocol required a single column purification technique.
- Mahendar, Lodi,Satyanarayana, Gedu
-
-
Read Online
- Preparation method of 9,9'-dimethyl xanthene
-
The invention provides a preparation method of 9,9'-dimethyl xanthene, wherein the preparation method comprises the following steps: dissolving diphenyl ether in a solvent, cooling, dropwise adding n-butyllithium, reacting, dropwise adding acetone at low temperature, cooling to room temperature, quenching with water, separating out an organic phase, concentrating an ether solvent, and carrying outcolumn chromatography purification on the obtained crude product to obtain the product 9,9'-dimethyl xanthene. According to the preparation method, diphenyl ether with low price is used as an initialraw material, a double-lithiation intermediate is constructed through hydrogen trapping reaction of diphenyl ether and n-butyllithium, and then the final product 9,9'-dimethyl xanthene is prepared through nucleophilic substitution reaction of the double-lithiation intermediate and acetone. According to the preparation method, expensive xanthone does not need to be used as an initial raw material,and an explosive chemical trimethylaluminum (superior to a xanthone methylation method) does not need to be used; the maximum separation yield of the method reaches 85%, and the method has high reaction yield.
- -
-
Paragraph 0019-0021
(2020/12/30)
-
- Preparation method of 9,9-dimethyl xanthene
-
The invention relates to a safe and efficient preparation method of an important raw material 9,9-dimethyl xanthene of an industrial catalyst Xantphos, and belongs to the technical field of fine chemical engineering. According to the preparation method, diphenyl ether, acetone and an acid catalyst serve as raw materials, a molar ratio of the raw materials is 1:1:(2-5), 9,9-dimethyl xanthene is prepared through a one-pot method, the yield can reach 70%-75%, and the content is 99% or above. According to the method, acid-catalyzed activated acetone and diphenyl ether are adopted for electrophilicsubstitution reaction to replace extremely dangerous trimethylaluminum and xanthone used in the traditional process for reaction, and the method has the characteristics of cheap and easily availableraw materials, safety in operation, high reaction speed, low requirements on production equipment and the like; and the production difficulty of the product is greatly reduced, and the yield of the 9,9-dimethyl xanthene can be rapidly increased.
- -
-
Paragraph 0016-0019
(2020/10/30)
-
- An electroluminescent compound and an electroluminescent device comprising the same
-
The present invention relates to an organic electroluminescent compound represented by chemical formula 1. An organic electroluminescent device comprising the organic electroluminescent compound of the present invention is able to be operated under a lower driving voltage compared to a conventional device with a phosphorescent hast material, and has excellent power efficiency, luminous efficiency, and service life.
- -
-
Paragraph 0163-0170
(2021/02/02)
-
- On the feasibility of nickel-catalyzed trifluoromethylation of aryl halides
-
A computational screening of 42 bidentate phosphines (PP) has yielded promising candidates for Ph-CF3 reductive elimination from Ni(II) complexes of the type [(PP)Ni(Ph)(CF3)]. The computed barriers and synthetic accessibility consid
- Jover, Jess,Miloserdov, Fedor M.,Benet-Buchholz, Jordi,Grushin, Vladimir V.,Maseras, Feliu
-
p. 6531 - 6543
(2015/02/19)
-
- Convergent functional groups. 9. Complexation in new molecular clefts
-
Two new 2,7-di-tert-alkyl-9,9-dimethylxanthene-4,5-dicarboxylic acids are prepared as organic soluble, U-shaped modules for the construction of molecular hosts. Condensation of two diacid units with spacers (e.g., hydroquinone, 4,4′-biphenol, and 2,6-diaminonaphthalene) gives large structures capable of assuming cleftlike shapes that complex sizable guests such as DABCO, quinine, quinidine, and quinoxaline-2,3-dione. The xanthene diacids and their derivatives are shown to contain intramolecular hydrogen bonds that organize the binding sites and modify their chemical properties.
- Nowick, James S.,Ballester, Pablo,Ebmeyer, Frank,Rebek Jr., Julius
-
p. 8902 - 8906
(2007/10/02)
-