New trends in the chemistry of α-fluorinated ethers, thioethers, amines and phosphines

Access to a new class of synthetic building blocks via trifluoromethoxylation of pyridines and pyrimidines

“…in chloroform (CHCl 3 ) at room temperature for 15 hours afforded the desired product 2a in only 29% yield (Table 1, entry 1). 27 Examination of different trifluoromethylation reagents such as 3,3-dimethyl-1-(trifluoromethyl)-1,2-benziodoxole (Togni reagent I, A ), 31 5-(trifluoromethyl)dibenzothiophenium trifluoromethanesulfonate (Umemoto reagent, C ), 33 and [(oxido) phenyl(trifluoromethyl)-λ 4 -sulfanylidene] dimethylammonium tetrafluoroborate (Shibata–Johnson reagent, D ) 34 revealed that Togni reagent I was superior to other reagents and delivered the desired product 2a in 42% yield (entries 2–4). Higher yield was obtained in the absence of Cs 2 CO 3 (entry 5).…”

Study on the residue and degradation of fluorine-containing pesticides in Oolong tea by using gas chromatography–mass spectrometry

“…Currently, about 15% of the pesticides listed in the 13th edition Pesticide Manual are fluorine-containing pesticides (Leroux, Manteau, Vors, & Pazenok, 2008). It was estimated that about 30e50% of total pesticides developed in the last decade are fluorine-containing pesticides (Manteau, Pazenok, Vors, & Leroux, 2010). As two major kinds of fluorine-containing pesticides, pyrethroids and benzoylurea pesticides are increasingly used to control a wide range of insect pests for many crops since they have some interesting properties such as effectiveness at low doses, low environmental persistence, easy biodegradation and low mammalian toxicity (Liu, Zhao, Zhang, Ma, & Liu, 2008;Muccio et al, 1997).…”

Are carboxylic esters really refractory to DAST? On the fluorination of α-hydroxyesters with DAST

“…of DAST, at higher temperature and longer reaction times, difluoro ether 8 is completely converted into tetrafluoro ether 9 (entry 4). As expected for highly energetic transition states, elimination products begin to appear when a large excess of DAST is employed at very long reaction times (entries 7 and 10) or higher temperatures (entries [11][12][13][14]. Accordingly, the reaction of the diethyl 2-benzyl-2-hydroxymalonate 6 (R = Ph) with 7 equiv.…”

“…AB = 14 Hz, 2H) 13. C NMR d 170.6, 134.1, 130.4, 128.1, 127.2, 122.5 (t, J = 271 Hz), 79.4 (t, J = 31 Hz), 53.4, 50.9, 37.8; 19 F NMR d À87.40 (d, J = 139 Hz, 2F), À89.77 (d, J = 139 Hz, 2F).…”