Mono- and dinitration of pentafluorosulfanylbenzenes with [NO2][BF4], and substrate selectivity (PhSF5 vs PhCF3 and PhSF5 vs PhNO2) in competitive nitration

Abstract PhSF 5 1 reacts with NO 2 + BF 4 − /TfOH in CH 2 Cl 2 (DCM) at room temperature to give 1-nitro-3-(pentafluorosulfanyl)benzene 2 in near quantitative yield. The dinitro derivative 4 is synthesized from 2 by reaction with NO 2 + BF 4 − /TfOH at 70 °C. The p -MeC 6 H 4 SF 5 is mononitrated at room temperature with NO 2 + BF 4 − /DCM and dinitrated with NO 2 + BF 4 − /TfOH. Substrate selectivity ( k PhSF 5 / k RPh ) in competitive nitration for PhSF 5 /PhCF 3 and PhSF 5 /PhNO 2 with NO 2 + BF 4 − in DCM at room temperature was determined at 21.3 and ∼1 respectively. Relative stability of the corresponding benzenium ions were gauged by DFT from the isodesmic proton transfer reaction SF 5 –C 6 H 6 +  + R-C 6 H 5  → SF 5 –C 6 H 5  + R-C 6 H 6 + (R = CF 3 and NO 2 ). These studies indicate that reactivity of ArSF 5 in S E Ar is similar to ArNO 2 .