Selective electrochemical synthesis and reactivity of functional benzylic fluorosilylsynthons

Electrochemical reductive silylation of meta-(trifluoromethyl)arenes by the sacrificial anode technique selectively led to meta-trimethylsilyldifluoro methylarenes (ArCF2TMS), in the presence of an excess of TMSCl and in a THF /cosolvent mixture (cosolvent = DMPU or HMPA). In the case of meta-(trimeth ylsilyldifluoromethyl)trifluoromethylbenzene, the influence of the cosolven t on the silylation selectivity was studied. A cyclic voltammetry study all owed an explanation of the difference in the results obtained between the t rifluoromethylbenzene and meta-bistrifluoromethylbenzene series. ArCF2TMS ( Ar = Ph, m-CF3C6H4) species were found efficient for ArCF2-group transfer t o diverse electrophiles under Fuchigami's conditions (KF catalysis in DMF). (C) 2001 Elsevier Science B.V. All rights reserved.