C-H trifluoromethylations of 1,3-dimethyluracil and reactivity of the products in C-H arylations

0429665 - ÚOCHB 2015 RIV JP eng J - Journal Article
Čerňová, Miroslava - Pohl, Radek - Klepetářová, Blanka - Hocek, Michal
C-H trifluoromethylations of 1,3-dimethyluracil and reactivity of the products in C-H arylations.
Heterocycles. Roč. 89, č. 5 (2014), s. 1159-1171. ISSN 0385-5414. E-ISSN 1881-0942
Grant - others:GA ČR(CZ) GAP207/12/0205
Institutional support: RVO:61388963
Keywords : oxidative trifluoromethylation * mediated trifluoromethylation * arenes
Subject RIV: CC - Organic Chemistry
Impact factor: 1.079, year: 2014

Diverse electrophilic, nucleophilic and radical C-H trifluoromethylations of 1,3-dimethyluracil were systematically studied in order to prepare either 5- or 6-(trifluoromethyl)uracil derivatives. Electrophilic reagents led only to dimeric bis-uracil products, whereas the radical trifluoromethylation by CF3SO2Na in presence of t-BuOOH gave 1,3-dimethyl-5-(trifluoromethyl)uracil (2) in good yield. The 6-(trifluoromethyl)uracil derivative 3 was only prepared in low yield and in a mixture with 2 by Ir-catalyzed borylation followed by treatment with the Togni's reagent. Attempted Pd-catalyzed C-H arylations of 2 in the presence of Cs2CO3 gave mixtures of de-trifluoromethylated products, whereas the reaction with 4-iodotoluene in the presence of CsF gave the desired 6-aryl-5-trifluoromethyluracil derivative 8 in moderate yield and the reaction was not general for other aryl halides.
Permanent Link: http://hdl.handle.net/11104/0234774