Journal of Organic Chemistry p. 7419 - 7431 (2016)
Update date:2022-08-15
Topics:
Jiménez, Eddy I.
Vallejo Narváez, Wilmer E.
Román-Chavarría, Carlos A.
Vazquez-Chavez, Josue
Rocha-Rinza, Tomás
Hernández-Rodríguez, Marcos
Thioureas are an important scaffold in organocatalysis because of their ability to form hydrogen bonds that activate substrates and fix them in a defined position, which allows a given reaction to occur. Structures that enhance the acidity of the thiourea are usually used to increase the hydrogen-bonding properties, such as 3,5-bis(trifluoromethyl)phenyl and boronate ureas. Herein, we report the synthesis of bifunctional thioureas with a chiral moiety that include either a trifluoromethyl or methyl group. Their catalytic performance in representative Michael addition reactions was used in an effort to compare the electronic effects of the fluorination at the methyl group. The observed differences concerning yields and ee values cannot be attributed solely to the different steric environments; theoretical results indicate distinct interactions within the corresponding transition states. The calculated transition states show that the fluorinated catalysts have stronger N-H···O and C-H···F hydrogen bonds, while the nonfluorinated systems have C-H···π contacts. These results have shown that a variety of hydrogen-bonding interactions are important in determining the yield and selectivity of thiourea organocatalysis. These details can be further exploited in catalyst design.
View MoreQINGDAO DEVELOP chemistry Co.,Limited
Contact:+86-532-85807910
Address:98#Nanjing Road, Qingdao, China 266071
Chengdu Baishixing Science and Technology Industry Co., Ltd.
website:http://www.cd-bsx.com
Contact:+86-28-88531548
Address:#217,North of Industry Road,Heshan Town,Pujiang County,Chengdu,Sichuan,China.
Wuxi Pharma-Trading Import & Export Co.,Ltd.
Contact:+86-510-82304590 82716390
Address:Room 523,Youzu Alliance Building,No.88 Renmin Zhonglu,Wuxi,Jiangsu,China
website:http://www.tcfinechem.com/
Contact:18681346930
Address:baifu town,whou district
Henan Techway Chemical Co.,Ltd.
website:http://www.techwaychem.com
Contact:+86-371-66380080
Address:No.27 Shunhe Road,
Doi:10.1021/jm00181a014
(1980)Doi:10.1016/j.bmc.2013.02.048
(2013)Doi:10.1002/ejoc.201700277
(2017)Doi:10.1016/S0040-4039(01)86636-3
(1979)Doi:10.1021/bi00868a041
(1966)Doi:10.1021/jo01302a039
(1980)