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 MoreShandong Wanda Organosilicon New Material Co., Ltd
Contact:+86-21-54177116;54302881
Address:R1318 Greenland No. 3 Lane 58 Xinjian East Rd., Minhang
Contact:+852 83038667
Address:Room 1502, 15th Floor, SPA Centre,53-55 Lockhart Road, Wanchai, Hong Kong
Contact:86-512-87182055
Address:No.128 Fangzhou Rd, Suzhou Industrial Park, China, 215125, China
Contact:+86-532-80762375
Address:No. 6, Hongkong Middle Road, Qingdao, China
Nanjing Chemipioneer Pharma&Tech Co.,Ltd
website:http://www.chemipioneer.com.cn
Contact:+86-25-52685700
Address:Room 305,A Block,Biological-Medicine Building,Business Start-up Center,Xin-ke 1st Road, High-tech development zone,Nanjing city,Jiangsu Province, China
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)