- Lability of the trifluoromethyl group of trifluoromethoxybenzenes under HF/Lewis acid conditions
-
The trifluoromethyl functionality of trifluoromethoxybenzenes (trifluoromethyl phenyl ethers) becomes labile under HF/Lewis acid conditions. Substrates with an unsubstituted para-position shed their -CF3 groups while performing a Friedel-Crafts reaction upon another substrate molecule's trifluoromethoxy group to generate p-rosolic acids. Substrates that had blocking groups at the para-positions reacted ortho. The electron donating substituents methoxy and phenoxy interfered with the formation of rosolic acids.
- Belter, Randolph K.
-
scheme or table
p. 1302 - 1307
(2011/02/22)
-
- 2-, 3-, and 4-(Trifluoromethoxy)phenyllithiums: Versatile intermediates offering access to a variety of new organofluorine compounds
-
Consecutive treatment of (trifluoromethoxy)benzene with sec-butyllithium and electrophilic reagents affords previously inaccessible ortho-substituted derivatives in generally excellent yields. 2-(Trifluoromethoxy)phenyllithium acts as the key intermediate. The 3- and 4-isomers can readily be generated from the corresponding 3- and 4-bromo precursors by halogen-metal interconversion with butyllithium or tertbutyllithium. Upon trapping of the 2-, 3- and 4-(trifluoromethoxy)phenyllithiums with 11 different electrophiles the expected products were formed in generally high yields. Only the attempted nucleophilic addition of 2-(trifluoromethoxy)phenyllithium to oxirane did not succeed. This failure is tentatively attributed to a lowering of the nucleophilicity by fluorine-lithium interactions. Conformationally restricted analogs - i.e., 2,2-difluoro-1,3-benzodioxol-4-phenyllithium and its 5-fluoro- and 5-bromo-substituted congeners - did indeed react smoothly with oxirane, affording the adducts in ordinary yields.
- Castagnetti, Eva,Schlosser, Manfred
-
p. 691 - 695
(2007/10/03)
-
